July 21, 2011
Renaissance architects demonstrated their understanding of geometry and physics when they built whispering galleries into their cathedrals. These circular chambers were designed to amplify and direct sound waves so that, when standing in the right spot, a whisper could be heard from across the room. Now, scientists at the University of Pennsylvania have applied the same principle on the nanoscale to drastically reduce emission lifetime, a key property of semiconductors, which can lead to the development of new ultrafast photonic devices.
The research was conducted by associate professor Ritesh Agarwal, postdoctoral fellows Chang-Hee Cho and Sung-Wook Nam and graduate student Carlos O. Aspetti, all of the Department of Materials Science and Engineering in Penn’s School of Engineering and Applied Science. Michael E. Turk and James M. Kikkawa of the Department of Physics and Astronomy in the School of Arts and Sciences also contributed to the study.
Their research was published in the journal Nature Materials.
“When you excite a semiconductor, then it takes a few nanoseconds to get back to the ground state accompanied by emission of light,” Agarwal said. “That’s the emission lifetime. It’s roughly the amount of time the light is on, and hence is the amount of time it takes for it to be ready to be turned on again.
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