报告摘要：In this talk, I will discuss applications of quantum mechanics in semiconductor heterostructures and devices based on three research subjects that I have worked on.  The three subjects are mid-IR interband cascade lasers, bipolar cascade lasers with quantum well (QW) tunnel junctions and quantum real space transfer.  Their current statuses will be presented to reflect different stages of research and development.  

The first, interband cascade (IC) lasers represent a relatively new class of mid-IR semiconductor diode lasers.  Using interband tunneling facilitated by broken band-gap alignment in type-II QWs, IC lasers reuse each injected electron in cascade sages for multiple photon emission with high quantum efficiency.  Since the proposal in 1994, IC lasers have been developed from concept to efficient devices with practical applications in chemical sensing and many other uses to come. 

Next, bipolar cascade lasers with QW tunnel junctions have been demonstrated at emission wavelength near 2 microns with the initial success in proof-of-concept.  In principle, they may be able to produce high output powers with narrow line-width, however their performance is still far behind expectations.

Lastly, quantum real-space transfer of carriers in semiconductor heterostructures is a proposal for the realization of a novel functionality, which relies on the wave nature of electrons governed by quantum mechanics.  Issues associated with realistic scattering are identified to unambiguously demonstrate the quantum real-space transfer in practical situations.  Specific QW structures for realizing the quantum real-space transfer are proposed with calculations for practical assessment.

报告人简介：Rui Q. Yang received the B.Sc. degree in physics from Zhejiang University in 1982, and the M.Sc. and Ph.D. degrees in physics from Nanjing University in 1984 and 1987, respectively.  He is the inventor of interband cascade lasers with research activities ranging from condensed matter physics to semiconductor quantum devices such as tunneling diodes, mid-infrared lasers and detectors.  Prior to joining OU as a professor in 2007, he was a Principal Member of Engineering Staff and a Task Manager at the Jet Propulsion Laboratory (JPL) in California, where he led the development of advanced mid-IR IC lasers for applications in Earth sciences and planetary explorations. He received the Edward Stone Award in 2007 from JPL for outstanding research publication and the successful accelerated infusion of cutting-edge interband cascade semiconductor laser technology into flight mission readiness.