Prof Milton Feng from University of Illinois at Urbana-Champaign illustrates how the transistor laser, a novel device with an electrical input, an electrical output and an optical output, opens up new optoelectronics integration frontier. His transistor laser research paper was selected as one of the top five papers of Applied Physics Letters in 2006.
Institute for Advanced Study Enquiries ias@ust.hk / 2358 5912 http://ias.ust.hk
Abstract
The invention of transistor by Bardeen and Brattain in 1947 lead us to realize that the "magic" of the transistor is intrinsically in the base. And, it is the base that potentially offers more, particularly when we arrive at the direct-gap, high speed, high current density heterojunction bipolar transistor (HBT) and realize the base although thin (10-100nm), has room for more layering (bandgap and doping) and can be modified.
Employing quantum-wells (QWs) and cavity reflection, we can re-invent the base region and its mechanics (its carrier recombination and transport fraction), reduce the current gain and achieve stimulated recombination, i.e., realize a transistor laser – a novel device with an electrical input, an electrical output and an optical output. The result is unique transistor in form and operation, as well as a unique three-terminal laser. Much more structure is evident in the output collector current and voltage characteristics owing to the sensitivity to QW bandfilling, state change, spectral change, mode hopping, change in optical field strength, and the effect of photon-assisted collector tunneling. We note that quantum well base region and stimulated recombination (stimulated emission), besides yielding a transistor laser, changes the transistor into an active element that can used for nonlinear and switching applications (both electrical and optical) as we recently demonstrated. With two electrical inputs through the base, we demonstrated new mixer with both electrical and optical outputs in nonlinear operation region and signals addition to produce new waveform in linear operation region. High Speed direct modulation of clear eye-diagram @ 20 Gbit/s will demonstrated. It is an amazing new device opens up new optoelectronics integration frontier.
About the Speaker
Milton Feng received his PhD degree in electrical engineering from the University of Illinois, Urbana-Champaign in 1979. He worked at Hughes Aircraft Company and Ford Microelectronics from 1979 to 1986. Since 1991, he has been a professor of electrical and computer engineering and a research professor at the Microelectronics Laboratory at the University of Illinois. In 2005, he was named Holonyak Chair Professor of Electrical and Computer Engineering. Along with Prof Nick Holonyak Jr, he demonstrated the first laser operation of a quantum-well-based light emitting transistor (QWLET), a transistor laser (TL) that opens up a rich domain of integrated circuitry and high speed signal processing that involves both electrical and optical signals.
Prof Feng has published over 200 papers, delivered 170 conference talks, and been granted 17 US patents in semiconductor microelectronics. He is an IEEE and OSA Fellow, and serves on many executive and strategy committees both in industry and at conferences. In 2006, his transistor laser research paper was selected as one of the top five papers in the 43 year-history of Applied Physics Letters, and also was selected as one of the top 100 most important discoveries in 2005 by Discover magazine.
Institute for Advanced Study Enquiries ias@ust.hk / 2358 5912 http://ias.ust.hk
