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Oral History Transcript — Dr. Eugene Gordon

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Interview with Dr. Eugene Gordon
By Joan Bromberg
At Eugene Gordon’s New Jersey Home
June 5, 1984

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Eugene Gordon; June 5, 1984

ABSTRACT: Move from MIT Plasma Physics group to Bell Telephone Laboratories (1957); Consultant to Javan group on gas discharge physics; first laser researches with A.D. White and J.D. Rigden; discovery of the visible He-Ne line, theoretical model for granularity of the spot, erroneous identification of the line; paper on masers (1964). Comparison of and interactions between research and development scientists at Bell Labs; development of research devices, ancillary facilities and reliability programs, funding; Gordon as supervisor. The single-frequency portable laser; the Holmdel group. The argon-ion laser, work with William Bridges, E. Labuda, Bennett’s talk on pseudo-CW lasers at American Physical Society meeting. Alan White’s tuning prism; the electro-optic modulator and origins of mode-locking. Administrative decisions at Bell Labs about experimental projects; Gordon’s duties as head of optical department. Work on acousto-optic deflection of light; applications of the argon-ion laser to medical research; development of diode lasers for room temperature operation. History of Journal of Quantum Electronics, Electron Devices Transactions, the Quantum Electronics Council, and CLEA.

Transcript

Session I | Session II

Gordon:

When you talk to someone like Kumar Patel, or whoever else you’re planning to talk to, at Bell Laboratories, one of the questions you might ask is, “How come Bell Laboratories didn’t get the first ruby laser? And Maiman at Hughes did?” You might find the answer very very interesting. It gives an insight into how science is done, and it’s not a political issue, it’s a technical issue. Basically what it amounts to is, some measurements were done about photo-luminescence, photo-luminescent efficiency in ruby, pumped by a flash lamp, and a mistake was made, and as a result of that mistake it was concluded that you couldn’t get ruby to lase.

Bromberg:

[Schawlow] had discussed this rather at some length, and he’s got some recollection that he published --

Gordon:

What about the question of why Bell Labs didn’t get the first semiconductor laser? Has that been discussed? Because Murray Gershonsen who was at Bell Labs at the time had done a really thorough job of understanding radiation in direct band-gap semiconductors, and in fact David Thomas and Bill Boyle, who were at Bell Labs at the time, (David Thomas is still there), had the first patent on semi-conductor lasers. I think it was a 1957 patent or something like that, and yet, somehow or other it was left to Lincoln Labs and IBM and General Electric to get the first ones to go, and I think that might shed some insight on how science works and how the Bell research area works.

Bromberg:

I guess what I’d really like to know is, as we talk about specific events and specific researches, -- we had three areas that we want to talk about -- if we can there bring up, you know, decisions and management attitudes and so on that will illuminate this concretely, I think that would be good. We decided, the three things we’re after here. One is the modulation work. Then a second is going to be the medical work, and a third is going to be the room temperature CW semiconductor laser. Let’s start with the modulation work.

Gordon:

Well, the modulation work was, as I described it last time, a natural outgrowth of the strong interest in communications, and in fact, there were a lot of different modulation studies done at Bell Laboratories. Larry Anderson, and Mauro DiDomenico were working on a traveling wave modulator where you got synchronism between the modulating microwave signal and the light so that you got an enhanced effect. And as I mentioned, there was the Fabry-Perot modulator, except the Fabry-Perot modulator, because it uses resonance, would be a narrow band kind of modulator, whereas a traveling wave modulator would be expected to be broad-band and indeed most of the current very high speed modulators that are being used today, for example, the type that Herman Haus at MIT is studying, are traveling wave modulators. So I did the work on the Fabry-Perot, and as I recall, we didn’t really do any experiments, because it just didn’t seem like it was the right thing to do. Although the paper, if I say so myself, was really a beautiful paper. It was really the first modulator paper, the first study of a Fabry-Perot modulator to use Maxwell’s equations and put in the right boundary conditions, and really did the whole job right.

As I mentioned, DiDomenico followed it up by putting in the cavity a time varying loss rather than a time varying reactance and added some gain, so that he could basically study the effect of a time varying loss in a laser cavity and see what effect that would have on the modulation. And he wrote an internal paper, a memorandum on that, which he asked me to review, and I reviewed it and pretty much had finished working on it on a Friday afternoon, and was going to send it back to him after the weekend. And I was at Temple on a Friday night sitting there listening to our rabbi give a sermon, and my mind started to wander and I began to think about his paper, and I suddenly realized that there was an infinite series in the paper that could be summed, and I summed it right then and there in my head, and realized that the result indicated that the cavity could be mode-locked, if the time varying loss were run at the speed equal to the spacing between the lines. In other words, in the cavity there is a comb of frequencies, and the difference frequency, let’s say about 100 megahertz, if you ran the internal loss at 100 megahertz, it would cause those modes to lock together, and instead of getting CW out of it you’d get giant pulses coming out at the 100 megahertz rate. And that was the theoretical foundation for internal cavity mode-locking.

Bromberg:

Now, this is independent of what Hargrove, Fork and Pollack had done, or independent of what De Maria is doing?

Gordon:

At that time?

Bromberg:

Yes.

Gordon:

I think they were doing it experimentally.

Bromberg:

They were, and then I think De Maria was also working through this analysis at the same time, about ‘64.

Gordon:

Let me make sure. DiDomenica’s paper may in fact have the first analysis. It’s not one of my papers, I wasn’t even an author.

Bromberg:

OK.

Gordon:

He inadvertently forgot to put my name on the paper. So it came out without my name.

Bromberg:

I see. That’s partly why I’m a little confused, I guess. So first of all, once you understand the DiDomenico paper as an interaction between the two of you, rather than --

Gordon:

Right, and I think it was just almost simultaneously with people beginning to see it experimentally and not really understanding what was going on. So as I recall, it was the first theoretical explanation of internal cavity mode-locking.

Bromberg:

At this point, you were not particularly in touch with this other group?

Gordon:

No, not at all. Except Hargrove wanted a tube. He proposed loss modulation and I told him he was crazy but gave him a tube anyway. I was wrong. It was just being at Bell Labs, you know, it is a tremendous community, and you don’t know everything that’s happening. So I was just vaguely aware of it, and wasn’t doing any experimental work at the time. I started the experimental work later. It came out as a paper by Mert Crowell, M.H. Crowell. He did it a very beautiful job on a helium-neon laser, gave it a thorough analysis, and did thorough experiments and it turned out to be his PhD thesis.

Bromberg:

Now, what was Crowell’s relation?

Gordon:

He worked for me.

Bromberg:

OK, so by this time you were head of the optical department.

Gordon:

Right.

Bromberg:

And so Crowell was somebody you gave this job to?

Gordon:

Right, yes, and it was the basis of his thesis at Brooklyn Poly.

Bromberg:

OK, and DiDomenico, was he one in your department?

Gordon:

No, he wasn’t. He was in another area, I think, a supervisor or a Member of Technical Staff at that time in another area, but again, it was the kind of thing where you were at Bell Labs, and if you were willing to go out of your way to talk to people and so on, you’d keep in touch with a lot of things, then you know what’s going on, and because I’ve always worked very hard at being willing to review people’s papers, and so people invariably would send me their stuff to read, and they’d always get good comments from me. Patel for example told me that I was the only person at Bell Labs that ever read his papers critically, and he’d always send them to me before they came out and I’d always send them back with lots and lots of comments. So that reputation stood me in good stead, because it allowed me to keep in touch with almost everything that was going on.

Bromberg:

I see, OK, that’s an obvious point which I just didn’t think of, that people are exchanging papers among each other, and getting back comments and revising them and having this kind of [interaction] -- when you became the head of the optical department, did that mean any change in the kinds of problems you were doing?

Gordon:

Oh yes, because it just broadened tremendously the area that I could work in. I now had the laser group and in 1965 -- because I was sort of working in optical devices -- they came to me and said we want to develop a camera tube, a vidicon, for Picturephone, so we’re assigning you the job of working on camera tubes. And so I got to establish a project on camera tubes, and --

Bromberg:

Were you working on memory too?

Gordon:

Yes, I was working on memory in a very interesting way. I’d been working on modulators, and typically I worked on some kind of modulator based on a time-varying index of refraction. And one day, Jack Morton, who was vice president of that whole development area, called me up to his office and he said, “Hey, look -- you’re working on modulators?” I said, “Yes.” He said, “Why are you working on modulators?” I said, “Well, you know, we need modulators for optical communications.” He said, “Well, we need light deflectors for optical memory, so why don’t you work on light deflectors? That’s a more important problem than modulators.” So he said, “Why don’t you see if you can invent some new kind of light deflector?” There was a project going on at that time under Klaus Bauer who’s the current vice president in that area, using potassium tantalate niobate, in a sort of a series of prisms, where you could deflect light, and it was sort of a digital deflector and in which a bean could be deflected into one of two positions, and those two positions then could be deflected two more (tape recorder fails)......etc. I studied various ways of deflecting light and got interested in acousto-optic deflection using scattering at the Bragg angle from an acoustic column. Varying the acoustic frequency changed the angle of the deflected bean. At the time acoustic transducers were too narrow band for a practical device and I tried microwaves in very high dielectric material (KTN). Martin G. Cohen was hired to work in this area.

The microwave work was not going well when I learned of work at Bell Labs under Friedolph Suits on wide band acoustic transducers. Thus Marty and I built up a good experimental system for acousto-optic light modulation and deflection studies. This led to a series of 12 excellent papers that pretty well established the engineering basics for acousto-optic modulation and deflection devices. There was one good physics paper that Prof. W. Low at Hebrew University in Jerusalem appreciated. We helped him get started using the technique to measure properties of fluids at microwave frequencies. I was able to attract Richard W. Dixon, a student of Bloembergen’s, to work in this area. (Dixon succeeded me at Bell Labs when I left). Several of the papers made the most cited list. All in all I am pleased with this work; its quality, its impact on technology and people.

The work that pleases me most relates to the use of the argon ion laser in medicine. Ed Labuda and I had an intuitive feeling that the laser would have medical application but we had no way of doing anything about it, nor did we try. Fortunately Dentzepis at Bell Labs, had a friend, Dr. Tom Brown, a neurosurgeon working in the laser clinic at the University of Cincinnati Children’s Hospital under Dr. Leon Goldman. Tom wanted access to an argon ion laser to do experiments in bloodless neuro-surgery. Since we had the only one or one of the few CW devices in the world at that time, Dentzepis proposed a meeting. As a result, we initiated a collaboration that saw Tom, Ed, Mel Johnson (an associate member of technical staff) and myself working on weekends in our lab at Bell Labs. Animals were brought by station wagon, the surgeons flew in, and Bell Labs graciously agreed to let all this happen. After initial experiments with mice, the surgeons were all ready to try something on a human being. I refused and insisted that we do experiments on larger animals. Brain surgery was done on a dog. Finally, late in 1964. I agreed to an experiment in which a portable laser would be brought to the hospital by Mel and used with other types of lasers on a woman terminally ill with skin cancer in a comparative study. Mel brought the laser, which had a maximum expected life of 100 hours, to Cincinnati. However, it was used to remove a tumor from a man’s leg. Photos were taken of the operation and one was immediately published in Goldman’s new book on the use of lasers in surgery. This was a first. None of this had my permission. I know nothing of the ultimate results. Goldman also tried to remove a tattoo from a young man’s fingers.

The laser failed during the experiment. Although I had never met Goldman, his complete absence of human and medical ethics, really appalled me. Consequently when in the course of an interview with a NY Times reporter I casually mentioned the medical experiments and a full article appeared mentioning the collaboration with Tom Brown and ignoring Goldman, Goldman became furious. Although Tom was blameless, he was fired and that ended the collaboration. Two of the fallouts of that collaboration was the experiments on rooster combs indicating that vascular tissue could be bleached by the laser beam yet remain healthy. This formed the basis for later port wine stain cosmetic surgery. The other was the invention by myself and Don Herriott, and the design by Warren Gronros, of the articulated arm to bring the laser beam from the immobile laser to a laser scalpel while maintaining a coherent beam. This became the basis for most later equipment designs. As a result of the NY Times article I was approached by Peggy Honig who was a hearing specialist at Manhattan Eye and Ear in New York. She had the idea that the laser could be used for ear surgery. Drilling microscopic holes in bone in the ear for attachment of wires. These wires were to provide an alternate sound path for diseased bone. This started a collaboration with Dr. Felix Shiffman of Manhattan Eye and Ear Hospital. We worked evenings during the week. Ed and I coupled the articulated arm to an operating microscope through a side port so the beam was focused on the cross hairs. A filter blocked the laser light but allowed yellow tissue fluorescence to pass. This provided the pointer. Shiffman proceeded methodically to develop his experience base on mice. By the end of 1965 we were ready to try larger animals. We applied for an NIH grant. By this time, Dr. Francis L’Esperance of Columbia Presbyterian Hospital was coming in too. He used a second identical system to experiment on rabbit eyes looking for a procedure for diabetic retinopathy. He worked with Ed. Felix worked with me. Unfortunately Felix’s boss at Manhattan Eye and Ear insisted on being part of experimental program and Felix quit.

That ended our collaboration. Fortunately the work with Fran went well. We bootlegged lasers for him to use at the hospital. In early 1968 he did the first procedure on a human, a twelve year old girl, who was being blinded by the curtain of vascular tissue associated with diabetic retinopathy. The rest is history Fran tells me that over 20 million clinical procedures have been performed and the success rate is 60%. The work on diode lasers sheds further light on the Bell Labs research elitism and has historical value too. When I became a director in 1968 I inherited a supervisory group under Art DaSaro, including Jose Ripper and Tom Paoli. Art had developed a stripe geometry version that generally allowed the lasers to operate continuously at slightly higher temperature than broad area devices in the same material. This became the model for all subsequent diode laser designs. However the material technology was primitive and room temperature, continuous operation had not yet been achieved. Mort Panish and Izuo Hayasui in the research area were trying to improve the quality of the double heterostructure material to achieve room temperature operature. Hayashi and Art were collaborating, Art planning to do the processing and Hayashi to grow the material. Room temperature operation would be a major triumph. Art was also trying to grow material and beat out the research people. I took the position that achievement of room temperature first by Bell Labs was most important and that collaboration was more important than competition. Thus I insisted that he stop growing material and work with Hayashi. To underscore my seriousness I told him that if he did succeed first I would not approve the publication. Art tried hard to collaborate. Hayashi tried hard too. But Parish insisted that no material was to be given to Art and Hayashi obeyed. Finally Parish and Hayashi achieved room temperature continuous operation in broad stripe devices. Their first was not clear cut because Alferov in the Soviet Union achieved the result simultaneously, more or less.

The devices did not last long and subsequent runs were unsuccessful. As a result, and in order to make a big demonstrations for management, material was given to Art to try to make stripe geometry lasers. This was the earlier material that had been denied to him by Parish. Of course, it worked at room temperature. Unfortunately, the denial by Parish and his desire to not share the glory with the device people cost Bell Labs a clear cut first. Art was not a co-author on the publication. The early devices were extremely short lived. I believed that fiber optic communication would come ultimately and that the right source would be a semi conductor laser. Thus reliability and stability became the key issue to me and I started a program under Barney DeLoach (department head), Dick Dixon (supervisor) and Robert (Bob) Hartmen (MTS) to Improve reliability and asked Ripper and Paoli to work on filaments and instability. This happened partly because the research people under John Galt went off on a stripe geometry kick and invented and published one structure after another with successively lower threshold current or other improved property. None of the papers mentioned reliability, which in general was terrible. I complained to Gold that reliability was a performance characteristic and absence of such data made the papers much less useful. He explained to me that reliability was my job, not his. And indeed he was right. Reliability almost invariantly is a second class job compared to inventing and publishing new devices and structures. He was explaining to me all over again that the relationship between research and development [sic]. Hayashi went back to Japan to help NEC start a laser program with immediate attention to reliability. DeLoach made important contributions to understanding the reliability problems (dark line defects) and gradually the key problems were revealed and solved. Similar progress was made at NEC. By 1975 it was clear that lasers could last a million hours at room temperature and confidence to begin system development was vastly enhanced.

The first experimental field trials were done in 1977. This final section I want to dedicate to comments on the research, development area interaction. Although I have been particularly scathing of certain individuals I want to add that among the people I most admire and like in this world are certain people in the research area or who had been in the research area of Bell Labs. Some people are bastards no matter where you find them and both the research and development areas had ample share. For example, I have no illusions about my perception in the eyes of others, both positive and negative. However, the research area had extraordinarily gifted scientists and fine human beings. The development area under Jack Morton was exceptionally aggressive and encroached unmercifully on the turf of the research people. So it was not one-sided. The research people had ample incentive to not like us. Perhaps in a climate where money and talent was unlimited the resulting anarchy was appropriate. However it was public money (license contract funding) and the enormous waste cannot be justified except partly by the full publication policy which made the information available outside frequently before it was available inside. Overall the climate was exhilarating and well designed to separate the men from the boys. If I had it to do over again I would choose the device development area over the research area. The emphasis on relevance to the Bell Labs communication mission, the emphasis on sound engineering principles, the discipline and teachings of Jack Morton, were all much more exhilarating than the mere physics.

Session I | Session II