Plasmon-based terahertz emission from quantum well structures

Growing coherent plasma oscillations (plasma instability) can be generated in quantum well structures, where a sufficient population inversion is main tained in the carrier distribution by appropriate injection-extraction conf igurations. The collective response characteristics of such structures have been calculated. Such structures have been grown, and their radiation emis sion spectra observed. The experimental results are in agreement with the t heoretical predictions. The emission maximum is in the terahertz frequency range, and occurs at an intersubband plasmon frequency. This shows that pop ulation inversion is achieved in these structures. (C) 1999 American Instit ute of Physics. [S0003-6951(99)05238-9].