Number 57 (Story #3), November 27, 1991 by Phillip F. Schewe and Ben Stein THE SMALLEST LASER YET , a thumbtack-shaped device only 2 microns across, has been developed by Sam McCall of AT&T Bell Labs. The business end of his microlaser is an indium-gallium-arsenide semiconductor disk only about 400 atoms thick. Light (at wavelengths of 1.3 to 1.5 microns) in the disk travels around the edge in a "whispering-gallery" mode, a process analogous to the travel of sound waves around the dome of a cathedral. (Science News, 23 November 1991.)