AF-funded engineer earns honors for scientific achievements.

ARLINGTON, Va. -- After decades of research at the University of Michigan in areas ranging from materials to circuits, 2008 has been an especially noteworthy year for Dr. Pallab Bhattacharya, who earned numerous accolades from the engineering community.

This year, three organizations recognized Bhattacharya for his significant achievements. The National Academy of Engineering elected him as a member; the Institute of Electrical and Electronics Engineers Nanotechnology Council co-awarded him the first ever Pioneer Award in nanotechnology; and The Minerals, Metals, and Materials Society chose him as the 2008 John Bardeen award recipient.

These awards and recognition resulted from Bhattacharya's impact on optoelectronics and nanophotonics. His work with quantum dots has improved laser, optical communication, and long-wavelength detector technologies.

Quantum dots are very small, self-organized islands of semiconductors that behave like artificial atoms, explains Bhattacharya. One big difference, however, is how they behave when injected with electrons and holes, collectively referred to as charge carriers.

After dedicating considerable effort to understanding the dynamics of these injected charge carriers, Bhattacharya was ultimately able to use quantum dots to create a new type of laser that combined the best qualities from semiconductor lasers and atomic lasers.

"A decade ago, we were the only group in the world looking at the initial deficiencies of high-speed quantum dot lasers," Bhattacharya said. "We solved the problems and now they are awesome devices."

As he and his team learned more about the pros and cons of using quantum dots in laser technology, they found that some of the deficiencies in laser applications are advantages for long-wavelength detectors. One such advantage is the ability to use the detectors at much higher temperatures.

A current project funded by the Air Force Office of Scientific Research has extended this research to terahertz-frequency wavelength detectors. The Air Force plans to use these devices, which measure very long wavelengths, for multispectral detection in airborne and terrestrial settings.

In another AFOSR-funded project, Bhattacharya is exploring the possibility of growing quantum dot lasers directly on silicon, allowing scientists to use light instead of charge to route information on chips. This would eliminate the need for metal interconnects, which generally have problems with heating, electromigration, and propagation delays.

Over the next several years, Bhattacharya will continue his research, focusing primarily on silicon light sources and nanolasers with total dimensions no larger than their wavelengths.

Lachance is with the Air Force Office of Scientific Research.