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 maintained in the carrier distribution by appropriate injection-extraction configurations. The collective response characteristics of such structures have been calculated. Such structures have been grown, and their radiation emission spectra observed. The experimental results are in agreement with the theoretical predictions. The emission maximum is in the terahertz frequency range, and occurs at an intersubband plasmon frequency. This shows that population inversion is achieved in these structures. (C) 1999 American Institute of Physics. [S0003-6951(99)05238-9].