||Abstract: We start with a brief review on specific device physics of quantum cascade lasers (QCLs), such as a line narrowing with recourse to the presence of fast nonradiative relaxation processes. Stressing the importance of wavefunction engineering in QCL-design, we review our theoretical and experimental results on indirectly pumped quantum cascade lasers. In particular, high device-performance of a mid-ir long-wavelength (~15 μm), InGaAs/InAlAs, Fabry-Perot quantum-cascade laser based on the indirect pump (IDP) scheme is exhibited: a low threshold-current-density of ~3.5 kA/cm2, a high maximum output power of ~216 mW, and a high slope efficiency of ~346 mW/A, all at room-temperature. The observed extremely high characteristic temperature of threshold current, T0~450 K over wide temperature range, 320~380 K is ascribed to strong suppression of electron populations in injectors, which are specifically visualized in the IDP scheme. The feasibility of the IDP scheme for high temperature (> 250 K) operation, without the assistance of high magnetic fields, of THz quantum cascade lasers is discussed, showing our latest experimental results on 3.9-THz IDP InGaAs/InAlAs QCLs with a very low threshold current density of ~340 A/cm2 at ~10 K.
Masamichi Yamanishi received the B.S., M.S. and Doctor degrees, all in electrical engineering from the University of Osaka Prefecture, Osaka, Japan, in 1964, 1966, and 1971, respectively.
In 1966, he joined the Department of Electrical Engineering, the University of Osaka Prefecture, as a Research Associate. In 1979, he was appointed as an Associate Professor with the Department of Physical Electronics, Hiroshima University, Hiroshima, Japan, and in 1983, he was promoted to a Full Professor. He was a Visiting Professor (Sabbatical Chair) with Purdue University, West Lafayette, IN, in 1984, 1986, 1987, and 1991. From 1998 to 2001, he was the Dean of the newly established Graduate School of Advanced Sciences of Matter, Hiroshima University, and from 2001 to 2003, was the Vice President with Hiroshima University. In 2004, he moved on Hamamatsu Photonics KK, Hamamatsu, Japan. Now, he is a Research Fellow with Central Research Laboratories, Hamamatsu Photonics KK., and is also a Professor Emeritus with Hiroshima University.
He was involved in experimental and theoretical research on 1) surface-acoustic-wave devices, 2) 2-D distributed-feedback lasers, 3) theory of polarization dependence of optical transitions in semiconductor quantum-well structures, 4) electro-optic properties of quantum well structures, 5) quantum manipulation of spontaneous emissions in semiconductor micro-cavities, 6) THz-electro-magnetic wave generation by polarized-exciton-polaritons in micro-cavities, 7) photon-number squeezing in semiconductor light-emitting diodes, and 8) intrinsic linewidth of quantum cascade lasers and proposal of a new pump scheme named indirect pump (IDP) scheme for quantum cascade lasers. He is the author of three book chapters on physics and applications of quantum-well structures, and co-editor for an issue of Selected Papers in Physics: Quantum Manipulation of Radiation Field and Matter (Physical Society of Japan, 1997). He has published more than 160 refereed papers in scientific and technical journals and given more than 100 contributed talks and 42 invited talks at major international conferences. His current research interests include quantum cascade lasers and meta-materials.
Dr. Yamanishi is a Life Fellow of IEEE and a Fellow of the Japan Society of Applied Physics, a member of the Physical Society of Japan and the Laser Society of Japan, and an Editorial Advisory Board Member of Laser Focus World, Japan. From 1996 to 1998, he was the Far-East Editor, International Journal, Progress in Quantum Electronics (Elsevier Science). He co-chaired Optical Society of America Topical Meetings on Quantum Wells for Optics and Optoelectronics in 1989, and Quantum Optoelectronics in 1991, both at Salt Lake City. He is a recipient of Optics and Quantum Electronics Award of the Japan Society of Applied Physics in 2001 and the 60th Cultural Award of the Cyugoku Shinbunsya (a News Paper Company in Hiroshima area) in 2003.