Materials and Photonics Engineering of Intraband Lasers

Presented by Prof. Gottfried Strasser, Center for Micro- and Nanostructures and Institute for Solid-State Electronics, Vienna University of Technology, Austria

Photonics is seen to be one of the most important key technologies in areas such as information and communication, lighting, security, or life science and health. A working growth and processing facility for semiconductors can be seen as a pre-requisite for the demonstration of next generation devices. It can be used for basic studies in material sciences and solid state physics as well as demonstrating novel concepts and applications of nanostructured semiconductors. Combining nanostructures and optoelectronics to nanodevices can contribute to the development of novel concepts and devices.
As an example for sophisticated multilayer structures I intend to talk about intraband transitions used for the generation of light, namely quantum cascade lasers (QCLs). Advanced design concepts of active regions as well as waveguides over the last decade persistently extended the lasing properties of QCLs by means of accessible frequency range, temperature behavior, power output efficiency, tunability, multicolor concepts, and nonlinear effects. In contrast to bandgap semiconductor lasers a large degree of freedom for surface structuring methods makes QCLs an ideal model system to study interference and coherence effects. Combining various resonators and filter structures not only allow selection of the wavelength, but also to have directional surface emission and beam control.  Recently we developed a novel material system for THz QCLs: InGaAs/GaAsSb, lattice matched to InP. This aluminium-free material system allows to combine a moderate conduction band offset with the lower effective InGaAs electron mass, offering a higher gain compared to GaAs based THz QCLs.

Gottfried Strasser received his Ph.D. degree in Physics from the University of Innsbruck, Austria, in 1991. From 1988 till 1992 he was research assistant at the Walter Schottky Institute (TU Munich, Germany). In 1992 he became assistant professor and in 2001 associate professor at the TU Vienna, Austria. Since 2007 G. Strasser is full professor at the State University of New York in Buffalo (Departments of Electrical Engineering and Physics) and since 2009 full professor at the Solid State Electronics Institute, TU Vienna. G. Strasser is heading the QCL research group at the TU Vienna, established molecular beam epitaxy (MBE) at the TU Vienna, and is head of the Center of Micro- and Nanostructures. He is an internationally renowned expert in III-V semiconductor devices and is author and co-author of more than 600 publications.