Boston Chapter of the IEEE Photonics Society

Abstract:  In this talk we discuss our work on two different types of semiconductor lasers. Ultrafast semiconductor modelocked laser with power levels approaching that of fiber modelocked lasers and nanoscale surface and edge emitting semiconductor lasers with sizes approaching that of a silicon transistor.

Mode engineering in monolithic semiconductor modelocked lasers has resulted in output power levels in hundreds of milli Watt range. Such power levels are more than 100 times larger than the maximum power levels that were available from monolithic modelocked lasers five years ago. We discuss the characteristics of high power electrically pumped modelocked semiconductor lasers, their stability requirements, pulse widths vs output power tradeoffs, and also active-hybrid modelocking of high power modelocked lasers.

In the second part of this talk we discuss ultrasmall electrically pumped semiconductor lasers in which surface plasmons are used to confine the optical mode in nanoscale (~100 nm size) cavities. Surface plasmon losses can be compensated in the near-IR wavelength region by the strong mode confinement in the gain region provided by the surface plasmons themselves. We show that surface-emitting lasers with narrow single-lobe far-field radiation patterns are possible even with subwavelength cavity sizes. The characteristics of nanoscale semiconductor lasers, including threshold currents, output coupling efficiencies, and modulation bandwidths will be discussed. Preliminary  

experimental results for nansocale optical cavities will also be presented.

Biography:  Farhan Rana obtained BS, MS, and PhD degrees all in Electrical Engineering from the Massachusetts Institute of Technology (MIT), Cambridge, MA (USA). He worked on a variety of different topics related to semiconductor optoelectronics, quantum optics, and mesoscopic physics during his PhD research. Before

starting PhD, he worked at IBM's T. J. Watson Research Center on Silicon nanocrystal and quantum dot memory devices. He finished PhD in 2003 and joined the faculty of Electrical and Computer Engineering at Cornell University, NY. His current research focuses on semiconductor optoelctronics and terahertz devices. He is the recipient of the US National Science Foundation Faculty CAREER award in 2004.

Location:  MIT Lincoln Laboratory