Arthur Schawlow

Bromberg:

What I was going to begin by asking you is this: in the reports that you sent, the interviews you sent me, they do say that your father, in Latvia, already had an early interest in electrical engineering. But I was wondering if you could begin by saying something about your parents' interests as you were growing up.

Schawlow:

Well you know, it's really a little strange to me that he did study electrical engineering. He did have a text book that he had used after he came to the United States; he had I think enrolled in a night class, or something like that, and he had a textbook on dynamo electric machinery, but in fact, he was not the least bit practical, that is, with things. He was an insurance agent, and this was a very lowly job in those days. The Metropolitan Life Insurance Company for which he worked had built its strength on what they called "industrial insurance," which was weekly, premium insurance. And so he had to go around every week and collect five cents, or twenty-five cents, and so on. And particularly during the 1930s, the conditions were very bad. A lot of people were out of work, and they lapsed their insurance. And the agents were paid on commission for new insurance, but then anything that was lapsed was deducted from their new stuff.

So a good many agents ended up paying the company, and they just couldn't keep the jobs. He did manage to keep the job all through the thirties, but it was a hard time, and he worked very long hours. He had to be out every eveing, collecting. So, he never fixed anything around the house as far as I know. My mother was the kind of person who would fix things in some crazy way that was wrong by the books, but she'd get it fixed, you know, with a hairpin, or something like that. So she did all that sort of thing around the housr. When I was little, I was really pretty clumsy, and my mother, I think—some doctor suggested that I should get a Meccano set (SPELLING?), which is sort of a British equivalent of the Erector sets, and I remember her sitting on the porch with me, patiently helping me put together the first few pieces of the Meccano set; and I still am pretty clumsy with my hands, but that was one thing that got me interested in technology. There used to be a Meccano magazine, which I would read in my teenage days, and it had a lot of stuff on engineering. The editor was a man named Ellison Hawks who had written a book called Halouze Pioneers of Wireless, and I used to go in the summer to the library, practically every day I'd get another book or so, and read it, and a lot of these were about aviation or electronics or radio, and so I really knew the history of radio in a popular sense, very well, when I was a teenager.

Bromberg:

Were you already thinking forward to being a scientist, at that point?

Schawlow:

I had wanted to be an electrical engineer—radio engineer, but there wer two obstacles. This was the depression, when I finished high school in 1937, and I—we didn't really have much money, and so I thought I would need a scholarship. There were no scholarships for engineering at the University of Toronto at that ime, and also, they had a requirement that you be seventeen years old for engineering, and I was only sixteen, barely sixteen when I finished high school. And so, we didn't know quite what to do. In Ontario at that time, if you had high enough grades, you could graduate without taking the provincial final exams, and I did, but if you wanted to apply for a scholarship, you had to take these exams. And so, well, a lot of people in the 1930s took an extra year in high school because they couldn't find jobs, and I—well, nobody from our school, which was fairly new, had ever won a science scholarship.

The science teaching wasn't very good, but somehow I took the exam, just to, well, see what would happen. And, you know, not really making up my mind where I was going. To my surprise, I got a scholarship for mathematics and physics. And I had though that otherwise, you know, I'll find some way to get a job and go to engineering school. Anyway, I got the scholarship, and found myself in mathematics and physics. And I thought, well, that's pretty close. I think it was a very fortunate thing to me, because I'm really not cut out to be an engineer, now that I know mor about what engineers really do. Because I'm much more interested in ideas and concepts than I am in the mathematical details of design. An engineer has to design a thing thoroughly. I was surprised to find that engineers really use a lot more mathematics than scientists do.

To tell you about my father, he wasn't strong at practical things, but he was good at mathematics, and he used to very much encourage me to study mathematics, and occasionally discuss it with me a bit, although he didn't have much time. And I think he could have been a pretty good mathematician. And maybe on that side, he could have been a good engineer. So I took mathematics and physics, and then we specialized as we went on, we could branch out into pure mathematics or acturial science, or even physics and chemistry, or physics, or astronomy, and I took the straight physics route. And of course, this was at the University of Toronto, because we just really didn't have enough money to even think of going anywhere else. This was where we lived, and the tuition now seems ridiculously low, I think it was $150 a year, but if we hadn't had that scholarship, I don't think we could have managed it.

Bromberg:

You know, even before we talk too much about Toronto, is there anybody from your high school years we ought to put in here, any teacher, or any—

Schawlow:

Well, there were some people that influenced me. The mathematics teachers I think were pretty good, I remember Mr. George Tuck, was a rigorous teacher. And in physics and chemistry in my last year, I had a man named Robinson, C.W.T. Robinson. I think his training was mostly in chemistry. I don't think he knew an enormous amount, but he had the good sense to leave me alone. He told me, "just go ahead and do all the problems in the book. Do them at your own pace." And so I learned the the stuff by myself, but he didn't get in my way, which was awfully nice. That's about the only course where I really had that kind of experience, but he must have sensed that I was able to do the material I'd always had pretty good grades in school; I never felt that I was a genius, I'd skipped a few grades in grade school, but then I found that the work was enough to keep me interested, and did well. My sister said I didn't work very hard, but I thought I was working hard

Bromberg:

In one of the interviews, you spoke of a professor named Moffatt Woodside.

Schawlow:

Oh, yes.

Bromberg:

Was he an important person?

Schawlow:

No, not to me, no. He was a—that must have been the Victoria College interview. The University of Toronto has a system of arts colleges for the undergraduate. You enroll in the faculty of arts, it sounds strange in modern days, but everything except engineering or law or medicine was arts. And then you had to enroll in a college, because in fact there had been independent universities. There was Victoria College, which was affiliated with the United Church of Canada; Trinity College, which was Anglican, or Episcopalian, as we'd say here; Saint Michael's College was Catholic and University College, which was non-denominational and mainly Jewish. But I didn't know anything about that. Although we were members of the United Church of Canada, I didn't really understand this. I just asked some of our teachers what college I should apply to, and they happened to have gone to Victoria College, so that' where I ended up. But the college was oh, about half a mile away from the physics building and from where we took mathematics. We had to take one course a week at the college, one or two courses. So we'd be there for an hour or two a week, and I really didn't get to know anybody very much there. My sister knew Professor Woodside pretty well. He was interested in classics, in fact he was in classics at the itme, and he did give a lecture or so on Greek science. But I don't think I actually had a course from him. I guess I was talking to a frporter from Victoria College and I was just trying to remember some of the people that I had known there, at all, because I really didn't know anybody very much.

Bromberg:

Well, let's talk about the people who were influencing you.

Schawlow:

But I did have one remarkable achievement as an undergraduate: I got through four years of a good university without one single essay.

Bromberg:

Well, you made up for it afterwards.

Schawlow:

Yes, that's right. Well, you know, I always tell my students that there are three rules for writing. The first if them is the hardest one: "Have something to say." And second, "Say it." And three, "Stop." Ancl in high school, it had just driven me crazy having to write essays on what did I do on my summer holidays, when I hadn't done anything, really and I just really hated trying to write things when I had nothing to say. Now my daughters, who are more literary than scientific, find it easy to write what I think is just endless words about nothing, but I can't do it. So,-anyway, I took courses, at the college, we had to take some cultural courses, and one I would have liked to take was religious knowledge, but that required essays, so I took Greek and Roman History instead, and French, and—oh, it was fun, but the real serious work was at the university. Ther was one other man that I should mention, a man named Crittle, William J. Crittle

. He was a radio technician. He'd been gassed in World War One, and had a pension, and he was unemployed through a good part of the thirties, and I used to spend many hours talking with him about radio and electronics. And this was stimulating, and I learned some, but mainly, it sharpened my wit a bit to try and think things through for myself. And of course, I had boyfriends who wer interested in radio, by the time I got into high school, I had met some people who were interested in radio, and talked with them a good bit, particularly William B. Michael, who got an amateur radio station around that time. Then at college, I worked with a lab partner, Hugh, who also had been a radio amateur. I wasn't, because I was an American citizen, I'd been born in the United States, and never became a Canagian citizen, so I could not get a license to be a radio amateur. Which was a great disappointment but, that's thw way it was. I also was in the Boy Scouts, though I was not much of an outdoor type; I did go to camp once.

Bromberg:

Well but in college, now, were you already working with Crawford there?

Schawlow:

No, well, let's see, I had a course from him as an undergraduate. The courses at the University of Toronto were very much prescribed. They had the honor course system, you see; when we decide we're in the mathematics and physics course, then almost everything is prescribed, except for the couple of hours a week that the colleges would teach. And so, you didn't have much coice. You took freshman mathematics; I had actually a marvelous teacher for calculus, Samuel Beatty, who was dean of the faculty—he was head of the department, and later was dean—oh no, I guess he was already dean of the faculty of arts, and later became, I think, chancellor of the university, and a really marvelous teacher. I remember hearing students-the class applaud when he introduced a clever substitution in an equation. Well, it was a standard thing that every mathematician knew, but he just built up the suspense of "How do you solve this?" But most of the mathematics was terrible... lectures, and ah, physics, we had a brilliant freshman teacher, John Satterly, an old Englishman, and I guess I try to emulate him a little bit in my lectures.

He was a real ham, you know, he'd do demonstrations and he undignified, if he could get a point across, and make the class laugh, and learn. He was not so good for advanced courses we found out later, but he was reallv excellent for freshman physics. I did have Crawford, I think for a light course as an undergraduate, but I really got to know him particularly when I was working there during the war. Now, the war started in Canada in 1939, and so before we graduated, in 1941, the involvment was pretty deep. And in fact they decided, in about February of 1941 that they would just simply end all classes in physics, and just put all the students to work. And I did stay there at the university for several years, teaching courses to—in fact, until '44, teaching courses to students from the army, the navey, and the air force. Just teaching them basic physics that they would need to be things like submarine detector operators, or radar was the big thing, they didn't tell us what it was for, but we had to teach them the elements of physics.

Bromberg:

Did you get a chance to do any thinking about physics in that period?

Schawlow:

I managed to squeeze in a master's degree. I did some research on a centrifugal battery that was supposed to somehow be activate~ when it was to go up in a shell. Well, I learned later this was something intended for a proximity fuse. But there was just another student and I, and very little resources, and well, we got enough to write a master's thesis on it, but I think it didn't get into application, because much better work was being done in the United States at that time.

Bromberg:

Now, who was leading you in this kind of endeavor?

Schawlow:

In this, it was a man named Pitt, yes, Arnold Pitt. I had actually worked for him one summer, he was a professor of physics, but he was really more in radio engineering Iwould call it now, radio physics, and he was in charge of this project: but basically, they turned this little part of it over to Morris Rubinoff and me, Rubinoff was another student, he later became a professor in computer science at the University of Pennsylvania. Anyway, we just did what we could pretty much by ourselves with occasional consultation with Pitt, but he wasn't involved in it closely.

Bromberg:

Did you learn anything from that?

Schawlow:

Oh, nothing of any great significance, I don't think. It was interesting to try and do. I'm trying to relate it to undergraduate work. Well, I was interested in radio at the time, and I'd build a few radios, although I never was very good at it, and read a lot. I remember as an undergraduate, the experiment I remember most enjoying was an experiment in our third year laboratory which Professor Satterly ran, where he just gave us a balloon, a large rubber balloon several feet in diameter—it could be blown up to that—and a pair of calipers, and said, "Find out something about it." Well, we measured the pressure, and the relationship between pressure and diameter, and looked to see whether there was anv elastic strain of such a kind that would depolarize light through it, it was a lot of fun, just turning us loose. This master's project, well, one had the feeling that it could have done a lot better if we'd had, you know, some more facilities, and knew a little better what we were really,trying to accomplish. But, I guess it was worthwhile. However, during this time, Crawford was teaching pretty much full time, in fact, night and day, working on these war courses, and there was another professor whom I'd also had some as an undergraduate, Harry L. Welsh. Welsh is now a very much revered, distinguished scientist, but at that time, they wouldn't even let him teach, because he had a bad stutter. He was allowed to run the laboratory, he was doing some research in spectroscopy, and working some with Crawford, But during the war they were so desperate for teachers, and Crawford insisted they give him a chance, and he developed into a rapid good teacher, although he speaks slowly. I think if he hadn't stuttered, he would have been too fast for us.

Bromberg:

He was teaching spectroscopy, is that what he was—

Schawlow:

Yeah, well, he was teaching the spectroscopy lab to the senior students. His research was in spectroscopy, as was Crawford's but during the war, they both taught introductory physics, freshman type physics to the army, navy, aid air force courses. Then after the war, I had courses in atomic physics from Crawford, and molecular physics from Welsh. But our graduate courses were really not very good, they just didn't go very deep, compared to what students at Stanford get nowadays.

Bromberg:

Tell me one thing, though, this work you did for a year on microwave antennas, did your radio interests feed into that, at all?

Schawlow:

Yeah, it did, actually. Of course, I'd been very interested in microwaves, and then when the classes ended at the university, I looked around for a job, and found they needed somebody at Research Enterprises. Actually, the man who was in charge of this particular project was Gordon Byers, who had been my lab partner for the first three years at college. I don't remember whether I got it through him, or not. I don't remember how that happened. He was not the group leader, a man named Charles Bridgland was, but he was sort of next to him and we did tests microwave wave guide antennas out at a field station that we had to have oh, about a half a mile away from the main plant, so we could look across the valley and have a receiver on the other side of the valley. Yeah, I was interested in wave guides, and I knew quite a lot about them, so this wasn't difficult for me, although I don't think I covered myself with glory, but I managed to do what needed to be.

Bromberg:

I didn't realize you had the microwave background.

Schawlow:

I hadn't really had much chance to do it any before, but I read everything; I read everything that was published on it, I think. I was interested. I really had the impression that the Germans had published rather more than the Americans and British. The Americans and British had been guarding their microwave technology during the thirties more than the Germans had been.

Bromberg:

You were reading the German in German, I assume.

Schawlow:

Yes, I could. It wasn't an awful lot, I mean, you're talking about maybe half a dozen or a dozen articles, it wasn't much. Yeah, I could read German; I had German in high school, and French also, although I never learned to speak either of them, but I could read them.

Bromberg:

So now, when you were just talking, I got the idea that you had not been planning to get a Ph.D.?

Schawlow:

Oh, goodness, no, that seemed like an aspiration I could hardly dream of. You know, practically nobody on our street had ever been to college. Although some of my father's brothers and sisters, with whom we had no contact at all had been. In fact he had a sister who was a dentist, and a brother who also was a dentist, and he had a doctor in the family too, but nobody else that we knew, none of my mother's relatives. In fact when I started to college, I thought what I might asprie to is to possibly be a high school mathematics or science teacher, or perhaps get some kind of a job in radio work, not quite knowing how. Well gradually of course during the war, I began to think I was able to get the master's degree, since I'd done rather well in undergraduate work. I had topped the class two years—the second and third years, and, I thought maybe I could do some graduate work. Then during the war somehow, although I had pretty much made up my mind that I would like to try and go for a Ph.D., I really didn't know whether I could or not. And you don't know, 'til you try it, really. We have a lot of students who—well, I guess anybody can get a Ph.D. but, it's strange how a lot of students who have very good grades as undergraduates just are not very creative when it comes to doing research. And I couldn't really tell whether I would be or not.

Bromberg:

Was there any particular reason to stay at Toronto, was it also a matter of money?

Schawlow:

Absolutely. Money, yeah. Although I think I could have gotten fellowship then, because graduate students were scarce after WWII, and lot of places had money. Toronto had very little. I got a part-time job teaching, which payed the princely sum of $660 a year. In fact, they tried to cut it to six hundred, but at this point, I protested, I and another fellow, that we'd had experience during the war, and it didn't seem right to cut us down. But that's about the only time I ever did argue about salary. And for that you had to do quite a lot of work, I think it was something like twelve hours a week, or something like that. But it was there, and I could live at home, so it seemed like the only possible thing.

Bromberg:

How did your family view this?

Schawlow:

My father was—well, they were very supportive. My father felt I should go to graduate school, and then go to Germany to study for a couple of years. Of course he was from the era where Germany was the place that one went. And he thought that's what I should do. And they certainly had to scrape to make it possible, but they did. During the war, I gave them all I earned, and they gave me what I needed, which wasnit very much, and afterwards my father managed, somehow.

Bromberg:

Was your sister still at home at that point?

Schawlow:

Yes. She got a scholarship the same year as I did to go to college. Well, I have to qualify that. She's a year and a half older than me, and she had repeated her last year of high school, and had gotten a scholarship that way, had gotten enough practice to get a scholarship. But she studied English. She graduated in '41, the same as I did. Now somewhere in there, she went to the United States to the University of Wisconsin for a year. She was gonna do graduate study there, she got a job teaching that would pay her expenses. Ah, that must have been toward the end of the war; I can't remember what whe did during the war, I think it must have been—she did work in libraries some, and some years later, she finally went back to school and got a library degree. But whe worked as an assistant in libraries, I think. But she was living at home too, and did until she got married in 1949.

Bromberg:

So, there were the four of you during your graduate years.

Schawlow:

Yeah, that's right.

Bromberg:

And it sounds as if you went into Toronto not feeling terribly enthusiastic about the quality of the institution there.

Schawlow:

Ya, I guess that's right, and I still feel it wasn't terribly good. I feel some really pretty serious lacks, I really don't know any quantum mechanics at all, hardly, because—in fact, I never really had a decent course in it. We had a miserable course in the physics department; there was a better course given in applied mathematics by Stevenson, but it was scheduled at a time when I had to teach an undergraduate lab, and I never could get free to take it. They needed me in the lab. So I really have some pretty serious deficiencies in my formal training in physics.

Bromberg:

What about the research possibilities, I mean, the work on nuclear structure with atomic—with spectroscopy.

Schawlow:

Well, as I think I've mentioned before, I really wanted to do nuclear physics, as that was a glamorous thing in those days, the forefront of physics, everybody thought, and the nearest thing to it was to do atomic hyperfine structure; and Crawford, whom I'd gotten to know both in class and during the war, and was a man who really thought about physics, and would speculate about it, would discuss it with students in an open way, not knowing all the answers, and knowing some of the problems. And so I spoke to him, and he suggested that I build an atomic bean light source. It took me a long time to do it, because nobody there knew anything about vacuum techniques, and the machinists really soldered it very poorly, and the joints were always cracking open, and it took oh, I think at least two years of my life chasing leaks in that thing. There was really nothing wrong with the design, except that it was soldered with soft solder, and when the air pressure got on it as you evacuated it, some joint or other would crack. And the only way we had to chck these joints was to take the apparatus apart, put brass plates across all the openings, and immerse it in a big tank of water, and blow air through it'and look for bubbles. Didn't have helium leak detectors, or anything like that.

We were very poor. Back in the twenties, the university had had a very good research program in physics, but during the thirties, the man who, very strong and domineering man who ran it in the twenties, J.C. McLennan, had retired, was replaced by a very able, rather amiable, but not strong man, Eli Franklin Burton, and during the depression one year, they asked would all departments please cut everything possible out of thier budget. And he cut out their entire research appropriation and they never got it back. At least not when I was around. Well, Carwford had worked double shifts, he and Welsh had, and they earned extra money for the university during the war, and some of that was put aside to pay for some research expenses. We bought a ten dollar thermocouple vacuum gauge, and I guess being inexperienced, I burned it out. And we could not afford to buy another one, and had to take it apart and rebuild it, and spot weld the wires, and make another vacuum gauge. Then, we were working with an interferometer that was very sensitive to the atmospheric pressure. Well, everybody knew what to do, you put it in a box that has windows for the light to get through, and close the box off, so the pressure can't change the density of the gas can't change in the box. But for that, we need two quartz windows. Not optical flats, just reasonable good quartz windows. Well, we couldn't afford them. So we had to stay up 'till we'd call the weather bureau, and find out when the atmospheric pressure looked like it wasnit going to— I was working with Malcolm F. Crawford, who was a very good physicist.

Bromberg:

working? No, I mean, wasn't there another student with whom you were

Schawlow:

Oh, yes. Yes, I worked with Fred Fred Kelly. He was older than me, he'd been out during the war. He'd gotten his degree I think in 1939 in physics, and then got a master's degree in meteorology. And he had then done some more work in meteorology, and he came back in '46, I guess, to start graduate work, and we worked together. And that was a help. I really need somebody to bounce my ideas off, and we worked well together. And then the third person came, also older than me. In fact, he'd been a teaching assistant when I was a freshman, and he'd been in the services, he'd been a graduate student before the war. He was an extremely timid person, was afraid to try anything. And I think I helped him. I remember once talking with him. His name was W.M. Gray, and he would write memos to the professor; and the proffessor would tell him something, he couldn't see how to do it that way. So I remember once telling him, "Don't do it that way; all Crawford wants vou to do is do it some way." And well, finally, he got the idea, and got his Ph.D. too. But we did various complementary parts of the apparatus. Since there was nothing there, really, we built everything. Kelly and I built the-light source, ad Gray built the spectrograph to analyze the light. This was really good experience. Crawford didn't really have any very specific problem in mind to use this thing on, it would give very sharp spectral lines, but he hadn't thought through what problems are worth investigating. Well, we found something in silver, which was my thesis, and something to do in magnesium, which was Kelly's thesis, and something to do in zinc, which was Gray's thesis. And that was good—good experience. We had to, you know, read the literature, and see what needed to be done. I also did a little bit of low power theoretical work on isotopes, it was really just analyzing some data, fitting them to some equations that had been published, but that were considered rather obscure, and nobody knew they were around.

Bromberg:

Did the three of you add up to the whold of Crawford's group?

Schawlow:

No, he had a couple of other students, in fact he had a lot of students after the war. He and Welsh had a joint program in molecular spectroscopy, and they had many students. Of course, that's an unstable situation, and eventually they agreed to disagree, and separate their groups. But he had some other good things—he was doing infrared. They were the first to show that you get pressure-induced absorption in the infrared in molecules that don't have a dipole moment, like hydrogen and oxygen and nitrogen. And he was also the first to show that you get electric field-induced absorption. That had been proposed by Conedon about ten years before, ten or fifteen years before. He had a wonderful knowledge and memory of the things that had been done in the twenties and thirties, knew where all these leftaver problems were, that had never been cleaned up.

Bromberg:

Was his microwave spectroscopy the link between Toronto and Columbia?

Schawlow:

He didn't have anything to do with microwave spectroscopy. His work was purely optical spec—

Bromberg:

Oh, I see, it was molecular spectroscopy.

Schawlow:

No, no it wasn't. The work I did at Toronto was purely optical, and I had very little to do with molecular work. As many people know, at that time, I developed the definition of a diatomic molecule, as being a molecule with one atom too many. It seemed awfully complicated, compared with the single atoms. Although I took a cours, I didn't do anything with it. The Columbia thing started because there was an organization formed in Canada called the Canadian Association of Physicists, which is still d reallv is sort of a Canadian enuivalent of the American going, an Physical Society, more nearly now. But at that time, it was set up as a sort of pressure group, almost like a union, because there were rumor that at the end of the war, physicists working in industry might have to register as professional engineers, to pass certain qualifying exams, to hold jobs working in industry.

This disturbed a lot of people, so the Canadian Association of Physicists was set up for that primarily. Well, they held a conference in Ottawa, and a group of us managed to get a car and drive up there. It's a hundred and fifty miles or so from Toronto. And it was terrible. It was mostly all stuff about the professional concerns and very little physics. And Rabi came on, they invited him, and he talked about work that was going on at Columbia, (this must have been in 1948), the work of Lamb and Kusch, for which they later got Nobel Prizes. This was really exciting stuff, at the forefront. So, when I was getting my Ph.D., I wrote to a number of universities, and particularly, I wrote to Rabi. I got nibbles, I could have had jobs, I think, at Michigan or Ohio State, but when I got an offer from—when Rabi wrote back, and suggested that I apply for this Carbide and Carbon Chemicals Corporation post-doctoral fellowship, to work on the applications of microwave spectroscopy to organic chemistry, with somebody named Charles Townes.

Now, I should have known about Towns, because I did read all the literature there. -It was amazing, you know, I really looked at everything that came into the physics library then. I read all the abstracts, because there just wasn't anywhere near as much as there is now. I think I was rather unique among the people around the department, because I just rally looked at—I didn't read, really read everything, but I looked at everything, scanned it. But anyway, his name hadn't registered, and I had absolutely no interest in organic chemistry, but microwaves I'd been interested in, and had actually worked on a little bit during the war. And been interested in it before that. In fact, we, Pitt had a klystron, an early Klystron microwave generator, and I'd had a chance to play with that a little bit, but not do anything serious with it. So, I applied, anyway, for that fellowship, and—

Bromberg:

So, this was entirely—tbis wasn't through your major professor, as sometimes happens, it was quite—

Schawlow:

No, he had to write a letter of recommendation, which he did, and I think he gave me a good recommendation, but it was—I did it on my own, I just wrote about and asked. And fortunately, jobs were plentiful, and physicists were scarce, that year. Actually, it was quite different a couple years later; when I finished at Columbia, jobs were a lot tighter. And I had thought, you know, at that time, I'd like to go to a university. But by the time I finished at Columbia I was getting married, and my wife wanted to stay near New York, where she was studying singing, and there just weren't any teaching jobs anywhere near New York, at that time. And so when the Bell Labs job came along I took that, somewhat unhappily; I mean, I really had thought more of a university and I didn't really know what it would be like to work for a company. Even Bell Labs.

Bromberg:

Well, we might talk a little bit about Columbia, and then talk some more about Bell Labs. I'd be interested in what the environment was like when vou came there.

Schawlow:

Well, it really was marvelous. They were somewhat crowded. They had a lot of war surplus microwave equipment, wave guides and oscillators, and so on. Columbia is a tall building, it was fourteen stories, something like that, at that time, none of the stories terribly big. Towns office was on the tenth floor, the contracts were administered by the Columbia Radiation Lab, which was on the eleventh floor, that had a Joint Services contract to support work in microwaves. They had a program for developing magnetrons, millimeter wave magnetrons. They were trying to get shorter and shorter wavelengths. During thw war, the Rising Sun Magnetron had been developed at Columbia, and they had apparently played an important part in developing microwave tubes during the war.

Bromberg:

Was the Union Carbide thing also going through this Columbia Radiation Lab?

Schawlow:

Well, let me tell you. It was affiliated with that. So. let me back up and tell you little bit more about how that happened. Charlie Townes, as you'll find out, if you don't already know, had gotten his Ph.D. at Cal Tech, in optical spectroscopy, and then come to Bell Labs early in the war, at the beginning of the war, sometime. And he had worked there on offset bombing and things like that. After the war, he really helped created the science of microwave spectroscopy. As he tells it, radar people had tried to use shorter and shorter wave lengths to get better definition. And they picked a very unfortunate waveleng1b, of one and a quarter centimeter. They'd gone from ten centimeters to three centimeters to one and a quarter. And there's very strong absorption in the atmosphere there. This meant that there was quite a lot of surplus equipment around, for that wavelength. And also, it was a wavelength where lots of gases absorbed. So he got a very strong program in microwave spectroscopy going at Bell Labs, so strong that Rabi hired him to come to Columbia. And he'd been there about a year when I got there, but be had a lot of students, and a lively group going on there. Now, the Carbide and Carbon Chemicals thing came about this way:

There was a man named Schultz, Ithink Howard Schultz, and if I can find it, I should like to find you a copy of a memorandum that he wrote during the war. He gave me a copy some years later. It's an unpublished memorandum, in which he bad suggested something that sounds terribly vague: that it might be possible to influence chemical reactions by using some radiation of longer wavelengths than ordinary light. Of course, photochemistry was known to some extent, then, and—it was a vague idea. He had been a chemical engineering graduate, got a Ph.D. at Columbia. I think in a laboratory accident he had somehow injured his eyes, so that he couldn't see well. I believe later his sight was restored, perhaps. I don't know a corneal transplant, or something like that. But at that time, he couldn't see very well, and they'd given him a sort of liaison job, and he had gone around trying to find some way to implement this idea of his that one could use wave lengths between visible light, maybe more like radio waves, to somehow influence chemical reactions. And he couldn't find any place where they were doing anything that was related at all. Except at Columbia, they were working to try and produce shorter radio waves in the magnetron project, and Townes was working very much on the interaction between microwaves and molecules and understanding it quite deeple.

So he decided the best thing to do was to endow for a few years a post doctoral fellowship for someone to come and work with Townes, on microwave spectroscopy. Somehow I was supposed to be related to organic chemistry. It turned out what I did had very little to do with organic chemistry, but it was on molecules, which is the stuff of chemistry. In fact, what Charlie suggested I do was work on the microwave spectrum of the free-radical OH, which had never been observed. And I did work hard on that, I very quickly got some equipment put together, but we never did find it while I was there. We had no optical equipment, so we had no independent way of knowing when we had OH in our apparatus. You'd run a gas discharge, an electrical discharge through water vapor, and then flow it through a wave guide cell. And the test we tried to use was one proposed by the chemist W.H. Rodebush, in Chicago, that you would condense the vapor on a cold trap, and then analyze for hydrogen peroxide. And his idea was you got OH radicals, and they would combine to produce H202. And we got logs of hydrogen peroxide, but we never did see any OH.

Until after I left, a student who started working with me, Mike Sanders, continued the experiment, and one night something happened to go wrong with the discharge, just at the time when he was on the wavelength of a line, and it turned out the conditions that Rodebus had suggested were not for production of OH. It was probably H02 or something else. And it was, it was tantalizing, because I learned from talking with Broida at the Bureau of Standards, and reading his stuff, that you could very well detecb OH from the ultraviolet spectrum, if you had just a small ultraviolet spectrograph. But Columbia had totally missed the days of optical spectroscopy. It had been quite dormant in the 1920s, and had really revived with Rabi and others in the 1930s. But by that time, optical spectroscopy was old hat, and there just was nothing around there that you could use to look to see whether you really had OH. Well, I worked with some other students on a few odds and ends of projects, but ah—

Bromberg:

But you were also working on nuclear properties, too, during that time.

Schawlow:

Well, that was just something we sort of did on spare time. I'd been interested in the theory of nuclear moments, because we were measuring them. There wasn't much theory at that time, or I guess I would have given up, O.K.? But I, well, I was just kind of looking at the stuff, and it sort of occurred to me that there might be some symmetry relations, and talked it over iwth Charlie, and put down some numbers, and it seemed to work out all right, so we wrote this paper on nuclear properties. And I guess also, I was asked to give a talk at the New York Academy on nuclear properties. I don't know what the real nuclear physicists must have thought about that work, but it was just something I was interested in, in thinking about. I also though a little bit about x-ray fine structure, where you could use the same theory that I'd had at Toronto for isotope shifts, and hyperfine structure. it is rather amusing; at that time, among the wonderful people who were there, were Oah Bohr, or as vould say, Aage perhaps—

Bromberg:

No, I would say "Oah." I lived in Denmark for a while.

Schawlow:

Okay, well, sorry; that's what one might think it is. He's the sone of Niels Bohr, and, ho, what a man! He is one of the smartest people I ever met.

Bromberg:

So he was at Columbia while you were there?

Schawlow:

He was for two years, yeah. He hadn't gotten a Ph.D. because in Denmark a Ph.D. is a very advanced degree, where you present a number of papers that you've published. But he knew more than almost anybody else. I'll never forget that Von Neumann came and talked at the theoretical seminar on the theory of turbulence, and I don't think anybody understood it except Bohr; he asked some apparently intelligent questions. And he asked me once to give a talk on what I'd been doing at Toronto on the theory of hyperfine structure, at the theoretical seminar. And I tell you, I knew what I'd done. A friend had pointed out to me an obscure paper, a Norwegian paper, using relativistic quantum mechanics. And 1, well, I got up and told about the calculations we'd done, and when somebody would ask a question, I would just keep quiet and somebody else would answer it, and then I would go on, because—when I got up and looked in the front row, there there was Willis Lamb, and I think Yukawa even was there, and Norman Kroll, and Henry M. Foley—really a high powered bunch of theorists, and I was just scared stiff.

Bromberg:

What a contrast to Toronto.

Schawlow:

Yeah, it really was. And everbody who was anybody came there. As I think I've said there were eight future Nobel Prize winners, including myself, Townes, Yukawa—he was there and got his a few months after I arrived. But Rainwater, and Bohr, and Fitch was a student, and Lamb and Kusch, of course, too. And you know, everbody—Wolfgang Pauli, I remember came there. He was a legendary name to us, but there he was, in the flesh. It was pretty exciting. And the American Physical Society meetings were held right there at Columbia, too, in those days.

Bromberg:

So, you'd see people at seminars, and I suppose just informally, you'd be talking to them?

Schawlow:

Yah, they had a very nice arrangement. I mean, they had tea every afternoon, which we've never seemed to be able to get going here. I guess we're too independent. And everybody just dropped everything and came to tea in this room on the eigth floor. And you had a lot of informal discussions at those, and Charlie was very good about introducing me to people. At that time, the research associates could become members of the Faculty Club, and since I was a totally unattached bachelor, I often ate lunch over there, and got to know some of the professors. I wasn't particularly trying to make a point of getting to know them, but it was nice. I got to know Rabi and Kusch, and some of the others who at there regularly too. So we would talk physics with the students, and Charlie had seminars, and so on. He's a marvelous person to work for, he knows so much more, but he somehow seems to be able to restrain himself. And, you know, if you come to him with a half-baked idea, a lot of people would just kind of crush it, and say, "Oh yes, well, that's so-and-so," but he would sort of listen, and help you kind of fan it, a spark into a flame, and really develop things, and He's better at that than just about anybody I've ever known, and I've tried to work that way with my students. But he was very good. He knew an awful lot himself, and was very strong in theory and in experiment. But he was just good at drawing out what was best in the students and associates.

Bromberg:

What other ways would you characterize his style as an administrator, or a scientist?

Schawlow:

He's incredibly hard working, and has an amazing ability to concentrate. We started the book on microwave spectroscopy in my second year there. He's more competitive than I am. He had quite a revalry going with Walter Gordy at that time, who was at Duke working on microwave spectroscopy, and they had some pretty irate discussions, because he felt that Gordy's people were trying to beat his students out to some of their projects. I don't know. But, the publisher was trying to get him to write a book on microwave spectroscopy, and he wasn't going to be bothered with it. Then he heard that Gordy was writing one, so he decided he would and he asked me to help with it. And so we started working on that thing, and we didn't finish it in one year, it's a big book, and an awful lot of work. We didn't finish it unitl '54, and it was published in '55.

Bromberg:

What did you do, divide up the chapters on that one?

Schawlow:

Yes, that's right, I drafted some of them and he revised them quite a lot, and he drafted the others. I didn't do much revising, because he knew the stuff. I didn't, I'd only been working on it for a year. And then after I finished, while I was working at Bell Labs, I would come in every Saturday, and work on these things. But—I'd sit in his office, and he was by then chairman of the department. And somebody would call up, or a student would come in to ask him something, and he would give them his full attention, and then he'd go right back to where he was. He just wouldn't miss a beat. And that's amazing to me, because when I'm distracted, I'm distracted, and it really is an effort to remember where I was; interruptions I find difficult. But he doesn't. He has an amazing ability of concentrating, and knowing exactly what he was doing.

Bromberg:

You know, speaking of style, there's an element of play in your style I surmise, and I wonder when that first started to come in. Is that from your very earliest...

Schawlow:

Yeah, I think so. I think so, I was a little bolder about revealing it, I think, after I had some success, particularly with the paper I did on infrared and optical masers. But I think I've always liked to try things out, you know, quick and dirty, and just for the fun of it. Yeah, I think that's just something inborn. I don't think I got that particularly from Charlie. He's rather more careful, and more of a planner.than I am. He's certainly a much better scientist than I am, in all sorts of formal ways. But I think I have pretty good intuition. I've really tried to train it, too, to develop it. That is, to have some sense of the order of magnitude of things, and really keep asking myself, "Now, what's this really all about?" Even though I may not understand all the mathematical details, I'll be able to cut through to the essence of things pretty well.

Bromberg:

It would be interesting just to know how else you would characterize your own style of work.

Schawlow:

Well, I don't know. I think I've developed the ability to work with students and let them work in their own way, and a lot of things that I've gotten credit for the last dozen years or so have been really done by the students, or post-docs. I've developed patience; though sometimes it's hard to let them

Arthur Schawlow reminisces about Columbia and how I. I. Rabi changed his thinking.

go ahead and do things when I'm caught doing the paperwork, and doing interviews and things like that. And sometimes it's frustrating, because I've had to wait sometimes a couple years before they understood what I was trying to get them to do. I don't know, it's really kind of amazing to me that I have actually accomplished anything, because I sort of have the feeling at times I really don't know anything. But I know a little bit about a lot of things, and I have a lot of curiosity, and somehow, ideas come.

Bromberg:

Now, what about Columbia ought we to be talking, before we get to Bell?

Schawlow:

Well, let's see now. Well, I certainly brushed up my microwave techniques there, and then I dropped that stuff quite abruptly when I went to Bell, which is a strange story. I guess what I got out of it mainly was getting to know Townes well, and talking with him, and seeing how he working with students, which was quite important to me in later years when I got to work with my own students, but not so important at Bell. And I just had a good feeling about what physics was about, and where it was going. Well, one incident I do remember that ought to go in the reocrd, was my lab was right next door to a lab occupied by one of Rabi's students, or some of Rabi's students, and in fact, there was a whole block of rooms occupied by Rabi's students, and this one of Townes' was at the end of them. And so, Rabi would come around once in a while, and of course, I was much intimidated by the great man, a Nobel Prize winner, and all that. But he went off to Japan for a month, then he came around and stuck his head in my door, and said "Well, what have you discovered?" And this really struck me, because, I never thought I could discover anything, you know. I might do something, but to discover something! It just sort of helped to raise your standards, and raise your sights, and so on: let's see if I can't pick out what's important to do, and not just do something. I can't think of anything specifically where I actually, you know, used it, but it really did sort of raise the tone of your expectations. You see other people who are not so very different who are doing very good things.

Bromberg:

Was he particularly important in this whole, you know, setting the tone for the, for what you—

Schawlow:

Yes, very much so. He was a very harsh critic of things, and a very good judge of people. He had a very tough program at Columbia. They would admit many students as graduate students, and then flunk out a lot of them at the masters level. And then they had a terrible thin, (I'm glad I never was a ttudent at Columbia), because after you'd finished all you Ph.D. research, you had to take a set of exams on the theory, and these would last several days, and were quite advanced, all on the graduate theory, not only your own work, but formal course work. And there were a number of students who did everything, the thesis and everything, and just never got their Ph.D. because they couldn't cope with these qualifying exams. Well later, when other universities became goo, Columbia couldn't get students to subject themselves to that sort of thing, and eventually, sort of over Rabi's dead body, they dropped that. But that was one of the things that made it such a good place. Kusch showed me a list of their Ph.D.s and it was quite amazing. I knew of practically every one of them, they all had became quite eminent scientists, in some wayway or other. Anyway, it sort of gave you some idea of what the real frontier of physics was like.

Bromberg:

Well, shall we start on Bell? For one thing, I was surprised, reading through your bibliography, I mean looking through it, that you suddenly wer in solid state physics.

Schawlow:

Yes, believe me, I was surprised, too. The reason was that Sid Millman was one of Rabi's former students and was then at Bell Labs, and later became director of physical research. But he was recruiting at Columbia. They used various staff members to establish contacts with the professors. And it turned out that at that time, he heard that I was looking for a job, and they had me out there. You know, I was pretty wary of this, because I didn't want to get into engineering, and at that time, I hadn't gotten over that I wanted to do physics, and hopefully something fundamental. And it turned out that John Bardeen had had some disagreements with Shockley and decided to get out of transistor physics, and then he got an interest in superconductivity, and the theory of superconductivity. And he wanted to have somebody doing experiments on superconductivity aroung there. Well nowadays, of course, if he wanted that, he'd get somebody who was a specialist in the particular branch of superconductivity. But there just weren't very many Ph.D.s aroung in those days, I guess. So they hired me to do research on superconductivity.

Bromberg:

Now, you went in there knowing that you were going to be—

Schawlow:

Well, superconductivity sounded like fundamental physics, and indeed it was. It was an unsolved problem, and I though, "Well, that sounds good, and working with Bardeen would be nice." But then Bardeen decided that he would accept a professorship at the University of Illinois; so I was hired in the spring, and by the time I got there in the fall, he had gone. So there I was, and I guess I was expected to do something on superconductivity, and with nobody to guide me.

Bromberg:

So you were really alone. Who was you supervisor at that point?

Schawlow:

The supervisor was Stan Morgan, who is a physical chemist by training, and he was a very good supervisor, but he really didn't know much about superconductivity, either. It was wonderful little group we were in. He and Schockley had been joint heads of the solid state physics department. I think they had Morgan there to smooth the feathers that Shockley ruffled, because Shockley is a very undiplomatic person. But they split up too, and he had the solid state group. And in that group, though, there were I think five people who've become members of the National Academy of Sciences, and three Nobel Prize winners, future Nobel Prize winners. So it was a group of about a dozen or so.

Bromberg:

So who was there? Lewis was one of them, I remember.

Schawlow:

Hal Lewis was one; and he's never done as much as one whould have thought, because he is clearly a brilliant person. He's gotten very involved in government things like the Jason Group. Lewis came I think a year or so after I got there. But Phil Anderson was there, (he was very young); and Conyers Herring; and Gregory Wannier, a marvelous theorist who just died this year, unfortunately. And experimentists, there were John Galt who later went into management, and became I think a high officer of the Sandia Corporation. But he was the one who had first shown that small fibers were very strong. He had bent the fibers under a microscope with a micromanipulator and whoed that single crystal fibers were extremely strong. Walter Brattain was in that group, too. He had been one of the co-inventors of the transistor, but he also had disagreed with Shcokley, and he and Bardeen had gotten into this group, and then Bardeen left.

So Brattain was a future Nobel Prize winner, and Anderson. And Conyers Herring and Bernd Matthias both became members of the National Academy of Sciences. So this group used to meet informally for tea every afternoon, with a few other people in basic research there. Bell Labs has a very clever system ther, whereby they keep the pure scientists organizationally separate, but they mix them geographically with other people like development people, so that they don't have all the labs right adjacent to each other, and you just naturally get to know some of the people in development and they got to know you, and occasionally you'll talk, and maybe ideas flow that way. But the experimental and theorectical people, the pure scientists would meet for tea every afternoon. And that was somewhat stimulating, although nobody else was working on what I was doing. It was very lonely, relly. I did talk with Lewis some. He led me woefully astray once or twice. And occasionally I'd get some help form Wannier of Anderson. Theorists were very helpful. There was a very nice spirit at Bell Labs. People would drop what they were doing, and discuss your problems with you. And they weren't all heavily overcommitted. Actually, I was around there for a few years before I really learned how to work at Bell Labs. I was a bit shy, and I sort of didn't really think my ideas were enough to kind of push on to people. But I realized that Bell Labs works very well. There are a lot of lonely people there who are doing their own individual thing. That's a matter of policy, because,they want to cover—keep an eye on a lot of different areas of science without committing large groups to them. But if vou get an idea, you can go around and get people to drop what they're doing and work on your idea for a few weeks. So you can get things done very quickly that way.

Bromberg:

Now, I remember your having some collaborators on those papers. Was that real collaboration?

Schawlow:

Yea, that came later I think, mostly. I had a technician, George Derlin—Lewis and Matthias and I did get an idea that seemed like fun, it really started with Matthias's idea on the intermediate state and Lewis did some theory on it. And we carried out the experiment very quickly. Well, Matthias wanted to see the intermediate state of a superconductor where it breaks up into domains, by sprinkling iron filings on it. And I suggested it would be better to use niobium filings, which would—the iron filings would be pulled into the magnetic field, and the niobium filings would be pushed out. But they would be out of the regions where the field is, and therefore they'd be less disturbing. And so Idid the experiment and it worked well, and we got a bit of publicity for that. Then I had other ideas, like trying to do the penetration of magnetic fields through a thin film, and Hal Lewis assured me that the penetration would be just down by the penetration depth factor, exponential minus the depth, the thickness of the film over the penetration depth, and that's woefully wrong when you have a hollow film. There's a lot of flux in the hollow, and the Shielding is much more efficient. So I wasted a lot of time on that. It was my idea, but as I say, Lewis assured me it was all right, and he was wrong. Then, well, I read Shoenberg's book, and tried to find things to do on superconductivity. I went to some meetings and I heard Livingston from Oak Ridge talk about nuclear quadrupole resonance, and it just seemed so awfully easy that I thought I'd try it out. And I did, and it was easy, so we published a few papers on nuclear quadrupole resonance, but I never was very deeply committed to that, it was really while I was getting set up to do something or other on superconductivity.

Bromberg:

In the meantime, you were doing the molecular spectroscopy book.

Schawlow:

That's right. That was killing weekends.

Bromberg:

That was purely extracurricular, then?

Schawlow:

Absolutely, yah. And that's why it went on so long. Didn't do that on Bell Labs time, at all. I guess I worked on it some at nights.

Bromberg:

It's a marvelous book, I must say.

Schawlow:

I remember when the book first came out, I was quite proud of it, and I was at that time sharing a lab with a man named Ted Benedict. And he overturned the pages thoughtfully, and then he said "Yep, okay for pressing leaves." (laughter) That's about all I've used it for. I was out of microwave spectroscopy by then. We did a lot of work, though, and I think we got a lot of stuff in it. But I felt when I started on the book there was no point in doing it at all unless we'd hope to make it a classic, something like Condon and Shortley; I just reallv wouldn't want to waste mv time on anv other kind of a book. And I think it was a good thing to have done it.

Bromberg:

As I said, I read maybe three or four chapters, and I just enjoyed it.

Schawlow:

Yeah, V, glad. Did you work in that field, or just in connection with Quantum electronics ?

Bromberg:

No, for the lser stuff, just to get background on this or that I would dip into it, and it's very widely available...

Schawlow:

Well now it's been reprinted by Dover. So, I worked on various things connected with superconductivity; it was a struggle, because there was nobody interested—Matthias worked on superconducting alloys, and in fact he shared a lab with me for a while, but I had a simple rule: He didn't run experiments very oten,, and wen he was there, I wasn't, because he was not easy to get along with, and he didn't want anybody getting in his way. But he spent most of his time preparing new intermetallic compounds and then small amounts of time checking their superconducting properties, so it worked out all right. But the people that I culd talk to were really people in England and maybe in Russia; there were some people doing similar things, ut it was pretty isolated.

Bromberg:

Did you get a chance to go around to conferences?

Schawlow:

I did get to a low temperature conference in France, in 1955. That was my first trip to Europe. I got invited to that conference, and went and gave a paper. And then I visited Oxford and Cambridge; that was some contact. And through the American Physical Society meetings, I got to know some of the low temperature people in this country a bit. But it was a small community.

Bromberg:

There's something I'm very ansious to ask you. At this time, I should think that Bell Labs was getting more and more interested in quantum mechanical resonances as a basis for technology. Did they approach you, and—

Schawlow:

Yes, they did, They asked me if I'd like to drop that and start working on masers. And I said "No;" I just really had gotten out of touch with that, and I didn't really have any very good ideas on the subject. That would be about maybe '57 or so, maybe '56.

Bromberg:

Who would that have been. Who was it?

Schawlow:

I think it was Millman, who was my boss's boss. They now call it laboratory director; then it was called the department head, and the immediate boss was the subdepartment head. And now they've inflated the titles to department head, for the former subdepartments, and laboratory directors for the next step up. When they did that, I couldn't resist that they should call the working-scientists "research executives," and the technicians should be "associate research executives." But they didn't do that.

Bromberg:

You weren't particularly in contact with the maser people there, or—

Schawlow:

No, I wasn't. I listened to it, it was interesting, but they were very energetic people and were pushing hard on it, and I just really didn't do anything. I sort of felt, well, that isn't my thing, and I don't want to horn in on somebody else's thing.

Bromberg:

Now, I know that you said in one of your memoirs, "From Masers to Laser," you said that

Arthur Schawlow talks about coming up with the idea of the dark ruby maser.

when it came to working on the dark ruby, Clogston and "Yes, go ahead," but was it already early at the stage when you were working with Townes on the paper that —

Schawlow:

No, it was in between. I guess what it was that, ah, after we finished the paper, I knew that Townes and Cummins and later Abella and Oliver Heavens, were going to work on trying to make a potassium optical maser at Columbia. And I never want to do what anybody else is doing, because I haven't much confidence in my ability to compete, and I don't like competing. And being at Bell Labs in the trasistor era, you felt that if you could do anything in gas, you could do it better in a solid. And so I started trying to learn about solids. And in fact, in that one paragraph in our paper that mentions that solids have broad bands for absorbing and sharp lines to emit it, I had just learned that much; I knew that ruby was that way. Now, ruby was a common material around there because a lot of people were working on microwave masers. So you could go down the hall and find somebody who had a drawer full of rubies or various concentrations, and could borrow a few samples which you'd never return.

So I just thought well, I'll get my feet wet, I'll try and learn something about this stuff, what's it all about. I had no idea of the theory, or anything at all about it. And I got hold of a copy of Pringsheim's book on Fluorescence and Phosplorescence. Which was one of these wonderful, thoroughly Germanic books that had all the references back to the early 1800s. It was very complete, but it didn't have the answers we wanted. At that time, I asked Clogston if Icould work on that, and he said "Fine." Then later there was another incident in the fall of 1958 after, the fall of 1960, rather, after Maiman had published, I was thinking about the dark ruby, and I really knew quite a lot about it, and I knew that those satellite lines, or "N" lines, were really very strong, stronger than the "R" lines, and I just felt that that dark ruby laser that I had proposed really ought to work. So I asked Clogston if he thought I ought to try it out, and he said, "You owe it to yourself." So, we did, and it worked. Right away. And of course, I should have done it sooner.

Bromberg:

Well, there are two things we—by the way, how much time did you want toward this?

Schawlow:

As much as you want. Do vou have another aDpointment afternoon?

Bromberg:

No. The other alternative is, if we don't get through today, then next time I come to Stanford, we can...

Schawlow:

I won't have any time tomorrow, unfortunately. I've got a lecture in the moring and then I have to leave right after the lecture. I'd like to kind of look over our files, and there may be a few documents that I can find that have some interest. As I say, on notes, I'm not at all likely to find them. When we moved across the country, I just didn't take much with me, I didn't have much. I wasn't very systematic, it was odd bits of paper, and I didn't carry them with me.

Bromberg:

Well, if we can some time at your convenience go through those things that you do have, like the correspondence, the student notebooks.

Schawlow:

Well, the studen notebooks are mostly — they would all be of course from the 1960s. Of course, we did some pioneering work on laser photochemistry here, and that would be documented in the work of Henry Warren Moos and William B. Tiffany. And we struggled with the ideas trying to get our thoughts straight, and made a little progress, not very much, but we did get started.

Bromberg:

That would also be on my next trip.

Schawlow:

Ikay, well, how long would you like to talk? If you have some specific questions now,...

Bromberg:

There are two things I would speak about. One would be to find out whether there's anything in this optical maser period at Bell that isn't on the record that we ought to talk about, that isn't in one of your articles.

Schawlow:

Let me think about that for a minute. I don't know whether I discussed the Clad rod laser in there. I don't remember whether I talked about that. That was of course after the beginning of the ruby laser era. I realized somehow that the light coming in the walls of the ah—yeah, let's talk about that a little bit. Let me back up a moment. Wehn Maiman published his first optical maser paper—(and incidentally, in that videotape,^[1] I do recount there my understanding of what the safu was in the publication, which I think I've already told you about. And I hope some day you're going to check with what Maiman was told, because I reported what I learned from Sy Pasternak, who was an editor of the Physical Review and Physical Review Letters at that time.) But Maiman just said, I think, that his crystal was of centimeter dimensions, and indicated that he didn't think there would be a beam, because of reflections from the other surfaces of the crystal. The picture that appeared in the newspapers, and I have a copy of that somewhere, if you don't have one, that very famous picture of Maiman with a flashlamp, up in front of his face, as I think I recounted, I learned later that wasn't the one he used. I have seen, actually had mry hands on, one that my be the one he used. It was rather smaller. But we though that sounded just like what I'd described already, so that's what we used when we tried our first ruby laser. Well then I felt that we could avoid reflection on the side by making the walls rough, and it did give a beam. But then a week or so later, the competing group at Bell Labs with Walter L Bond, G. Geoffrey B. Garrett and Wolfgarg Kaiser also checked their laser, got it working, and they also had a beam, and their sides were polished. And it was sometimeafter that I realized that the explanation was the the light is less intense at the outside of the rod than it is at the center, because the light's refracted on going in the sides of the rods, and therefore is concentrated at the center of the rod. And that led to the invention of the clad rod.

At that time, Linde was making the ruby crystals by the doorknob process, where they start with a small rod ruby, and then rotate it, heat it, and then drop powder on the outside of the thing, and it grows in circular lays as this rod is rotated, and it ends up something like a doorknob. So they were able to make me a rob which had a pink ruby core and a sapphire outside, and we realized that you could in fact get more intensity at the cord than you had at the surface. That was amusing, because a lot of people didn't believe it at first. They felt it violated thermodynamics, but when you get your thermodymanics straight, that's the way it has to be, in the medium, where the waves move more slowly than they do in free space. And that of course explains why Garrett and company had seen a beam, and in fact Maiman had observed a beam, too. This was reported by Maiman in the abstracts for the fall meeting of the Optical Society of America in 1960. He was invited to give a paper at that meeting, and his abstract was published probably September or so, but it must have been submitted in late July, I think. And by that time he had boserved a beam, but we didn't know it at that time. So anyway, they did produce a beam because of the fact that it was below threshold at the surface, it was absorbing at the side wlls of the rod while it was amplifying along the axis. And that's why the thing worked better than it should have. Now let's see, what else was going on around Bell Labs? Well, it was a very abrupt change for me from having been really isolated when I worked on superconductivity, to all of a sudden having more people than I had time to talk with. It was fun, but it was really a very remarkable change.

Bromberg:

Physically, you were in the same laboratory that you had been in?

Schawlow:

Yes, yes I was. And I did rearrange things. Actually, my cryostat had been in another lab across the hall. I guess Benedict had left by that time, so I had the whole room by then, and I managed to get a spectrograph, a large spectrograph in the thing. And I wanted to get a photographic spectrograph, and I remember the boss saying "Sure; where are you going to put it?" And there was no way to put a photographic spectrograph into that room. And that was the only limitatio-,.

Bromberg:

Who came in to talk with you, were they development people, or just other scientists?

Schawlow:

No, research people; a lot of people got interested at that time, some of the people who had been in device work, or communications. I don't remember just exactly who it was now, but I know that Jim Gordon who had been Townes' student working on the maser got interested in optical masers, and Gary Boyd, Bill Boyle —

Bromberg:

Were Fox and Li coming around at the time, or was that earlier on?

Schawlow:

I saw Fox occasionally; yeah, I saw Li occasionally, too, around those times I think he wouldn't be one who'd come around just casually. Satoru Sugano was there from Japan, and we had very fruitful collaboration on the physics of ruby, and other luminescence of chromium in magnesium oxide and that sort of thing. And Darwin Wood also, who was a spectroscopist, who did some collaborative work there. Just a lot of people! I did collaborate on things with a number of them, off and on, a little bit. It was certainly stimulating, but when I left to come here, I felt well, I've done it both ways. I can work in a hot field where there's a lot of competition, a lot of action, or I can work by myself on something that nobody cares about, and it was rather good to feel I could go either way. You need a certain amound of independence. There also was a slight unpleasantness, too, because there was some jealousy over whose name was going to go first on the paper, and who would publish what. In fact, I had been invited to give a talk at the ah, I was invited in maybe May or June to give a talk on the theory of optical masers at the NEREM CONFERENCE in Boston in the fall of '60. Well by the time it got close, the summer had come and gone, and I had to submit some sort of an abstract or something like that, for clearance; and some of the people in the other departments objected that I should be talking about the work that had been done collaboratively, whereas I was perfectly prepared, if they wanted, to just talk about the things I'd done all by myself ahead of time; but it was this jealousy, which was a bit disturbing.

Bromberg:

Was that just Bell Labs, or was that—

Schawlow:

That was within Bell Labs, that was within Bell Labs. And of course, I (we) weren't allowed to talk freely to outsiders for a while, because they felt this might have some patent importance, which had never been a consideration at all in my thinking before that. I just never thought about it; anybody that would listen, I would talk to. But it was not a bad place to work, just that when I got an offer from Stanford, and other universities—in fact, eight universities approached me in that year after the first laser operated, and Stanford looked about as good as you could hop to get, and a chance to work with students, I was just sort of bursting with ideas, I didn't have any group, and it seemed to me that at Bell Labs, you never would have a group to work on your ideas. They wanted people to be independent, and I appreciated that, but students whould need me for a while, while they were learning to do research, and that's one reason why I left Bell, and came to Stanford. Though I reallv wasn't unhappy there; it was a very good,placo.

Bromberg:

Were there other reasons that made you decide?

Schawlow:

Well, my son, for one thing; I have an autistic son, who's had the most amazing development. He's now twenty-seven years old, and still doesn't talk, but at that time we were sort of at the beginning of a pretty horrible nightmare that we've had through the years. But there was nothing for him in New Jersey, no medical school, no doctors that really knew anything much, no school for him to go to or anything lile that. And my colleague, Roberg Hofstadter had an autistic daughter, and he and his wife, particularly his wife, had worked hard to get a place set up for exceptional children, here, at Stanford. And that was a real attraction, too. And that worked well for a year or so, but then the director changed, and it wasn't good. We had some pretty horrible times. Well now, in the last few months, thank God, he's suddenly started to communicate with us. We've worked hard with computers and keyboard devices, and had a breakthrough; it turns out he can read, has been able to for years, and he can spell quite well, and construct quite grammatical sentences, and tell us anything he wants to tell us. He still doesn't talk, but he does it by typing. That's only happened since September this year. We're still pretty excited about it. That's where I'm going tomorrow. We got him out of that horrible state hospital, and he's living in a house, a group home in a place called Paradise, two hundred miles from here, in the foothills, the mountains. So that's where we go on weekends, Friday and Saturday.

Bromberg:

So, when you got here, well let's see, why don't we just finish up this tape, this side and the other side, or—

Schawlow:

Well, you've done the other side, haven't you? Oh no, this is a new tape, that's right. Thsi your second tape, yeah. Okay.

Bromberg:

At least, let's not go any more than this, and we'll see if we want to finish this up. I'd like to talk a little bit about when you got here, bow you began to set up. I noticed you worked with Emmett on flasblamps for a while, John Emmett.

Schawlow:

Well, Emmett really was interested in flashlamps. He was an amazing guy. I sort of had the feeling of having of tiger by the tail with him. He's one of these people that once you let him into the lab, he isn't interested in doing any more course work, or anything like tha

Bromberg:

Oh, he was a student?

Schawlow:

Yeah, he was my student. So was Linn Mollenauer, who has deveoped the color center lasers at Bell Labs. John Holzrichter who is I think the deputy head of the laser effort at Livermore, also was a student. So, we had good students here. The first student was an Irishman named Frank Imbusch. No, sorry Linn Mollenauer was the first student, then Imbusch shortly afterwards. It's funny, when I came here, some people asked me, "Well aren't you afraid? How can you do anything here? How can you compete with Bell Labs people?" And I've never felt I had to compete; I just do something

Bromberg:

field at that point? different, something they think is unimportant. Itis funny, I've just, well, I shy away from competition, I don't want to do it. The only times I've ever been dragged into it was when a student was committed to a project, and some competition appeared. But that's pretty rare. There's always so many things to do. In fact, I always had the feeling that if anybody anywhere in the world wants to work on any of my ideas, that's great, because I've always got ideas that people think aren't worth working on, and those are the ones that may turn out to be useful, that may turn out to be wrong, but they're fun, and there're enough of them to keep going. So, we didn't try to work on lasers, really, we worked instead on the properties of rubies, and related crystals, for a while.

Bromberg:

And you did a lot of solid state spectroscopy.

Schawlow:

That's right. And then later on, we got into doing spin wave sidebands, and exictation of magnetization by light, and things like that, too, that grew out of that. And that was purposely to be a little bit apart from the laser

Schawlow:

Yes. I couldn't really see anything much I could do with lasers. I mean, I didn't feel I was a design engineer, and it just seemed that that was a more interesting thing to do. I think I rather missed some opportunities to actually use lasers for spectroscopy; they weren't very tunable then, goodness knows, but I could have done some excitation, but I didn't think of doing it. But you can't do everything.

Bromberg:

One very striking point where you pick up what you were talking about years ago is with the Romine reation.

Schawlow:

Well I had been thinking about that. I mentioned my Scientific American paper, and well, Moos was a bit interested, and then we managed to get a student. It's hard to get students. Frankly, the reason I didn't continue that was twofold. One is that the possibility of separating uranium isotopes became painfully apparent, and I just don't want to do anything that has any chance of contributing to proliferation of bomb materials. I'm really scared of the time when terrorists can make bombs in their back yard. I have a horrible feeling it's inevitable, it's going to happen sometime, but I just don't want to contribute to it. The other thing was that I couldn't really get physicists to work on chemical problems. Bill Tiffany was willing to do it, but I wasn't able to get anybody else after that, very easily. Obviously, it was difficult, and dangerous, so I just said, I won't bother with that anymore. In fact, from the Schultz background^[2], I had a vague feeling you could control chemical reactions somehow, and I thought, let's try and see what we can do. But we didn't have very tunable lasers. All we had was ruby lasers, and you could tune that a little bit by chang ' ing the temperature. I had studied the temperature dependence of the frequency of the "R" line. And so Tiffany and Moos built a laer that had enough tunbaility. And well, you had to find something that could be excited by the ruby, and bromine was the only thing we could think of, but it turned out to be a terible choice, because the reactions of bromine tend to go as chain reactions, and you may start them off selectively, but they soon scramble. So I guess from a chemical point of view it wasn't very sensible. But it was about all we could do. That was sort of a left over idea from the earliest days. I mean, you should be able to do something about chemistry.

Bromberg:

I see, so there wasn't any really-ally these infrared spectroscopy experiments were quite separate conceptually, that were going on with you other students.

Schawlow:

Yeah, that's right. Well, I guess you say I like to play; that's true, I like to learn about a subject by getting in and getting my feel wet by trying something, doing some kine of experiment. And one of the things I'd learned by that time, which I've since formulated explicitly, is that it's really not hard to move into a new field and discover something. Because you never have to know everything about the subject. All you've got to do is recognize one thing that's not known. And you just read a few of the latest papers, and you see where they stopped. And you see where the gaps are. They'll lead you back to the earlier papers, and the literatue is so crosslinked that you're not going to miss awfully much that way. So it's really quite easy to move into a field with a different perspective, and do something, if you're in a pure physics lab, which we were, in the Department of Physics, not applied physics. And nobody was telling me that I had to do something useful. Well, we had to be, of course, developing techniques all along, as we went along. Emmett was a remarkable experimenter, and so was John Holzricbter They really had a kind of symbiotic relationship. I used to use what I call apostolic succession with my students. Typically, a student would work on a project, and then when he's getting nearly finished, I'd assign a new student to work with him for a while, and learn where the stockroom is and how you get the machinist to do things and that sort of thing. Well, Holzrichter worked with Emmett, and then Emmett went off to the Naval Research Lab, and then after Holzrichter finished, he joined Emmett at the Naval Research Lab, and then when Emmett went to Livermore, Holzrichter went with him, and they've both done brilliantly at Livermore.

Bromberg:

Did any chemists, or chemical industry people get into the act at this point?

Schawlow:

No. Dr. Schultz truned up after we published our first ppper, and he came out and asked whether there was some way that we could collaborate. We didn't have any good ideas, and they didn't have any good ideas, and so nothing came of it. I guess they would have liked us to go to work on some organic compound, and, well, it was just so primitive, you really couldn't do anything much at that time. It was just really premature. Now, let's see, Holzrichter did some beautiful, well, both Emmett and Holzrichter developed techniques for lasers. I remember that John Emmett—I had a hard time with him to get him to finish anything. He loved to keep improving the apparatus. And I had a rather interesting talk with him this last summer. And he told me that tht was deliberate. He didn't want to get out of there. He said he'd been taking formal courses for a long time, and not learning much that he didn't already 'know, and this was the first time in years that he'd been able to really do what he wanted to do in the laboratory. And he was afraid that if he got some results, I'd make him finish up, and go out and get a job somewhere, where he wouldn't be able to do what he wanted to do. But I found it rather tantalizing, because he wouldn't.

He kept improving the equipment. But he was interested in flashlamps, and he knew more about flashlamps as a student than anybody, anywhere is this country. In fact, I managed to wangle a grant to take him with me to the Varenna Summer School in 1963, that Charles Townes organized, on quantum electronics. And Charlie got talking with him and realized how much Emmett knew, so he had him give a lecture on the flashlamps there, and write it up for the proceedings. And the man from the Office of Naval Research was going to do a tour of Europe, to visit laboratories working on flashlamps, and he took Emmett with him, because Emmett was the American expert. I don't know quite where he learned it, but he really knew about flashlamps. In fact, we were being supported by NASA^[3] at that time, although we never did them an awful lot of good, I'm afraid. However, they bad money, and they were supporting some basic research in those days. And the man from the navy, the Office of Naval Research, Elliot Weinberg, who was supervising some of our work. We had some navy money, they'd put in some money, because they knew that Emmett had expensive tastes here, and they wanted to support it. But he was very anxious to learn whether flashlamps that were used for pumping lasers were opaque to their own radiation, whether they were black bodies or not,^[4] because they were speding $100,00 a year at General Electric, to try and seed these lamps with some substance that would absorb and emit more light in the near infrared, which they needed for pumping neodymium galss. Well, Emmett didn't have a tunable probe laser then, but he made a short arc lamp, which he simmered, to keep the discharge alive, with a low current, and then he would dump a large pulse of current through this thing, and then could actually measure the light transmitted through the flashlamp as it was flashing. And he was able to show that these lamps were in fact quite opaque in the red, and they only became transparent more toward the green or blue. And so it saved them a lot of trouble. But to get this done, and it was a relly beautiful experiment, a tour de force, Weinberg had to come here on Saturday mornings, and sit with Emmitt, and make him take observations. Otherwise, Emmett would have kept on making the apparatus better. Sp he had a little pick-up coil surrounding a crystal, at low temperatures, and he irradiated that. He had a slightly tunable dy laser. It was one of the early dye lasers, and he was able to pick up the magnetization induced by the light. He had a transistor amplifier at liquid helium temperatures, in the liquid helium, had cryogenics, and lasers, really a complicated experimental setup.

Bromberg:

Actually, there's a quite different question I wanted to ask you about this period. I found that you were coming into the councils of the Optical Society of America at about that time.

Schawlow:

I was the only person ever elected to the Board of Directors of the Optical Society and the Council of the American Physical Society in the same year.

Bromberg:

What I wanted to ask about that was, were you from the very beginning an OSA member, or was this something that just grew with your laser work?

Schawlow:

That's a very good question, because in fact, Mary Warga was the executive director of the Optical Society. He background was wpectrochemical analysis, and sh'd been a professor at the University of Pittsburgh. But by the time of the early laser work, I don't know whether it was before or after Maiman's work, whe decided that they ought to have this in the Optical Society. And she came up to Bell Labs and had lunch with a number of us, and persuaded us to join the Optical Society, and then made sure that a number of us were invited to give talks at meetings. Peter Franken has mentioned that particular meeting in Pittsburgh in 1961, when there was a lot of excitement about the early results on lasers. But Mary Wargo particularly got me to join the Optical Society.

Bromberg:

That interests me very much.

Schawlow:

I had not been a member when I was at the University of Toronto; I did join the American Physical Society in 1945, and I was a member of the IEE then. I dropped out of it though, after I went to Columbia. I decided well, I'm really in physics, not engineering, and I rejoined it again in 1962, or something like that, I think, after the engineers were getting interested in lasers and things related to it. But the Institute of Radio Engineers, up till then had seemed to be rather removed from what I was actually working on, you know, when I was working on superconductivity, and things like that.

Bromberg:

By the way, when you said you read all the journals, did you go through the IRE as well as the physical journals?

Schawlow:

Yes, I was a member at that time. In fact, I must have joined it during the war, yeah. All there was was the proceedings of the IRE. Yes, I did read that. I got that. The physics library didn't get a huge number of journals but physics abstracts you got free with your membership in the American Physical Society, and I'd look through all the abstracts, which wasn't very much, in those days. I was just interested.

Bromberg:

Well, that's something that I hadn't guessed. I don't know whether I should have guessed it or not. Another thing we ought to get a little bit of in your early days at Stanford is—

Schawlow:

In skimming the things at Columbia while working on the book, I found that paper of Weber's on what later became some partial idea of using stimulated emission for amplified radio waves, and I showed it to Charlie Townes, and he looked at it, and said "well, there's nothing there we don't have." But I remember, I just found it as I was browsing through everything I could find. Anyway, back to Stanford.

Bromberg:

I was just going to ask about your contact with other groups, and with other people here, people outside here.

Schawlow:

First, I tried to kind of make this a focus, had seminars which allowed people who came from industry and from other departments, public seminars, and announced the talks. Siegman was already here in electrical engineering; he had been working on microwave masers, and was making the switch to optical stuff. It's interesting, one of his student was Steve Harris, who's now a very eminent faculty member, and one of his students was Robert L. Byer, who is also an eminent faculty member now. But I did at first have these seminars, which were attracting people from industry, and from other departments. I did consult for a while with Varian Associates, but that was a very frustrating experience, because they kept changing their mind as to what they wanted to do. They got in and out of lasers several times, and they missed a lot of great opportunities. You know, Arnold Bloom and Gene Watson and Earl Bell were there, and wanted them to get into lasers, and they wouldn't do it, so Bell, Bloom and Watson went off and formed Spectra-Physics.

Bromberg:

Did you consult with Spectra-Physic8, at all?

Schawlow:

No, no, I never have. Other companies..I was involved with Optics Technology, which was in the end unsuccessful in business. I was even a director of that for a while. But they were into too many things. They had a lot of great ideas, but not good marketing. Various companies would come around here, and sort of look at what we were doing, and take what they could use, but we didn't have much contact with them.

Bromberg:

Is there some cros-fertilization when you do something like work with Optics Technology? Do you get ideas that feed into the research, and vice versa, or are they disjoint?

Schawlow:

It's never worked out awfully well for me. I don't know. Some people it does seem to help, they seem to get cross-fertilization. I guess some of the laboratory experiments I've developed, or demonstration experiments, had something to do with the contact. Optics Technology made cheap portable helium neonasers, the first commercial helium neon lasers with internal windows, (windows on the ends of the tube). Unfortunately, they didn't have enough control over the materials, and the epoxy seals they used on the windows would slowly, after six months or so, let in enough water vapor so that they would destroy the tubes. So they had to replace practically a whole year's production, with this delayed effect. That was the beginning of the end for them. No, I don't think that my contacts with industry were very fruitful in our work. Well, I did get some lanthanum fluoride and related crystals from Varian. They were growing some crystals. They thought they would get into materials, for a while. Ed Herold from RCA was director of research, and he felt they should have a good materials effort. And they hired a crystal grower, It was Hugh Muir who like to grow fluorides, rare earth fluorides, and they were interesting materials, so we did some spectroscopy on those because they were available. But they kept changing their mind; they thought they would get into lasers, and then would decide they could spend their money better on other things, and they were probably right. I think it was three times at least, while I knew about them, that they started to get into lasers, and then decided no, they couldn't, they could use their money better elsewhere.

Bromberg:

Is Optics Techology a firm that I should—we should be interested in, in the project?

Schawlow:

Yes, Narinder Kapany was the founder of Optics Technology. It was one of the first firms. They made one of the first ruby lasers for eye surgery, and they made this helium neon laser, which is the first sealed off one with internal windows. I remember, speaking of contacts with other companies, I actually posed for an ad for Spectra-Physics. They had a picture of me with Earl Bell, examing the suitability of their laser for classroom use, or something like that. Didn't endorse it, but they lent me one on indefinite loan, after that. 'Unfortunately, it was stolen. It must have been one of the first lasers stolen from a lab. Somebody around here, I gather some student. We never got it back, but they suspected some student was collecting all kinds of electronic equipment, cause stuff was being stolen around that time. But that was all. I mean, I just posed for this thing, and then they lent me their laser. I was just trying to help them. Yes, Kapany, He's now the president of Kaptron, Incorporated, which is particularly in fiberoptics, but he certainly has some rich experiences from those days.

They did work with some eye doctors, and made a ruby laser for eye surgery very early. It might have been as early as 1962 or so. He was one of the founders of the fiber optics field. He was a student in England with Hopkins, who developed techniques for making good glass fibers. But the trouble was, that he had so many ideas that he'd keep introducing a new product every year that would sell to a different market. They were in medical lasers, they were making optical transfer function devices for testing lenses, and making night vision devices with microchannel plate image intensifiers, you know. Just so many different things that from a business point of view it never made sense. Because they never really perfected any of them. You know, back during the sixties, I used to joke that I had a sure fire way of making money, by invesing in laser companies. Just pick any laser company and sell short. And that would have made you a lot of money in those days, because they were dying like flies. I often wondered how many years it must have been before the laser business, as a whole, was producing a net profit, because so many companies the investors would put in several million dollars and lose it all. Oh, there were a lot of companies that came and went in those days.

Bromberg:

Not before '73, I think, at the earliest. That's what ital Laser Focus—

Schawlow:

Not before—were they making any money? Yeah, I think that's so; I think Spectra-Physics had some profitable years in there, but it was pretty touch and go. And maybe Coherent Inc. did, too. I think probably that's about when the industry was starting to profit. I think that's one of the great strengths of the American industries; there are people who are willing to gamble and lose money, in the hope that they'll make a lot of money. And so new things get off the ground very fast here. It was an advantage being in Silicon Valley, particularly when we got into tunable lasers in the seventies. And Ted Hansch did develop good links to the companies around and was able to get the latest equipment as soon as it was available, and that sort of thing. But I never was able to do that. I didn't really know how to go about trying. It just didn't seem to work out.

Bromberg:

We have time for one or two more things, I guess, at most. Were ther other groups in other countries that ought to be on this record as important interacters with you? There was Chebotyeu, I think-

Schawlow:

Well, he was rather later, I think. 'He would come in the late sixties and seventies, although he's very, very good. Now, wait a minute, wait, no no no. I'm wrong. I met first at the Varenna Summer School, he was there. So, no, I guess his best work was done later, but he was active then. And Letokhov, also, although I didn't meet him until later. There were groups in England; Birch, at the National Physical Laboratory, or laboratory, was mainly an optics man. He built a very early ruby laser in England, and did some work on the theory of spiking. No, wait a minute, no, he did build that laser, but Dunsmuir who did work on the theory of the spikes that you observe in the output of ruby lasers.

Bromberg:

What we want to do, though, is those people you were most in contact with. Were you in contact much with Javan's group? Things that were important in your own carrying on of work, if there were such.

Schawlow:

Not really. We were pretty self-contained. Perhaps too much so. Well, the people I worked with—there was a meeting in memory, in honor of Gerhard Dieeke of Johns Hopkins University, time in the late sixties. And I think there were about fifteen people with whom I had been co-author on various papers, mostly from Bell Labs. We had some visitors from Bell Labs who came here for a while, Mike Sturge was here for a summer, and Dar Wood was here for a summer. And we had some useful discussions while they were here. And Declan Larkin spent a summer here from Treland. So we had a number of visitors, and we did have some good discussions with them. But there really wasn't much influence. No, they were doing their thing. I knew Ali Javor very well, of course. I'd known him at Columbia and at Bell Labs, and I think he's terrific, I really admire the things he's done. But he was off in the infrared, and doing molecular spectroscopy and harmonic generation and so on, and it just didn't seem to overlap what we were doing.

Don McClure at Princeton I would occasionally run into in connection with the solid state spectra and I made good use of his articles in Advances in Solid State Physics, which were the best kind of textbook, they sort of reviewed the whold field. And I also had some discussion with John E. Wertz at the University of Minnesota, particularly about the spectrum of chromium in magnesium oxide. But I talked mostly to my students at that time. I left Bell very soon after the start of the laser era, and you know, at meeting, I would talk to all sorts of people, people who were pioneers. Elias Snitzer at American Optical is certainly one that it would be good to get, sometime. He was right in there. Bob Collins at the University of Minnesota would be a good one, he was at Bell Labs in the early days, and he went to the University of Minnesota a few years after. Kaiser is now at Munich, at the University of Munich. Wolfgang Kaiser, tht is. I talked to everybody, but I really wasn't working on lasers when I came here, so I didn't really interact a lot with them. I was curious and I kept in touch, and I was writing popular articles, and giving talks so I kind of kept a shallow but broad view of the subject. Of course, not wanting to get involved in military stuff kept me out of some circles, which was partly why I didn't get involved, because otherwise I would have been on every government laser committee. I wouldn't have been able to do anything.

Bromberg:

Well, what do you say we stop now?

Schawlow:

Okay, sure.