Effects of Coupling on Inter-Subband Transitions

Abstract

This paper outlines an attempt to probe into the issue of inter-subband transitions from a different angle — coupling effects. It describes some of our latest efforts in exploring the potential of electronic and photonic couplings for selective control of the inter-subband transitions and in understanding the related coupling mechanisms and effects. Specifically, three types of coupling mechanism are discussed: the spatially direct band-to-band coupling, the spatially indirect band-to-band coupling, and the long-range photonic coupling. The aim of this work is to achieve a good qualitative understanding of the primary effects and their physical origins. Detailed and quantitative modeling and calculations — tasks more suitable for separate publications — are left out of this condensed article. While emphasizing the physical origins of the coupling effects, the discussions are extended to the configurations of new quantum well structures and device consequences, where appropriate.