Abstract

When dealing with light-matter interactions, textbooks refer usually to the ideal quantum mechanical two-level system. For many applications, however, this two-level model represents a too simplified description of real solid state systems. To study light-matter interactions beyond the textbook model, two-dimensional semiconductor heterostructures in combination with terahertz time-domain spectroscopy (THz TDS) may serve as an ideal experimental test bed. The number of quantized energy levels, their spacing, and the transition dipole moments can be engineered at the growth stage of the structure. In addition, the coherent generation and detection of broadband THz pulses enables the simultaneous measurement of changes in amplitude and phase induced by the sample under study [1]. For example, this scheme has been successfully applied to the phase-resolved study of gain dynamics in THz quantum cascade lasers and the observation of gain clamping [2]. Additional insight into the internal dynamics can be obtained by using intense THz pulses strong enough to drive the optical response into the nonlinear regime.

© 2013 IEEE