The Rochester team of graduate student John Marciante and Professor of Optics Govind Agrawal clean up the semiconductor laser beam, creating a sharply focused beam with more power and precision. Semiconductor laser power is limited by the tendency of their beams to fragment into a number of parallel, weaker beams, which limits their use in surgery, where higher power and precision are critical. Agrawal and Marciante propose inserting two extra layers of slightly modified semiconducting material on either side of the active layer of gallium arsenide, where the beam is formed. The layers we're inserting induce negative bending, resulting in a net bend of zero for the laser beam, keeping it sharply focused. While a prototype has yet to be built, Agrawal says the new laser performed well in computer simulations.
Semiconductor lasers offer several advantages over gas lasers.
They're more durable and more user-friendly since they have no gas tanks to replace or mirrors to care for. They can be mass-produced, thus usually cost only a few thousand dollars, compared to tens of thousands of dollars for a comparable gas laser. The work is funded by the Univ. Of Rochester and the U.S. Air Force Phillips Lab. The new awards, created last spring, recognize demonstrated excellence and promise of future success in scientific or engineering research, and the potential for eventual leadership in their respective fields.