Design of intersubband quantum well far-infrared lasers
A strongly asymmetric stepped and a parallel quantum well (QW) far-infrared laser structure are proposed. The QWs have been carefully tailored so that the subband wavefunction features favour population inversion. The overlap ratios of the pump light and the lasing light with the QW layer can be improved by placing a thin germanium layer on top of the structures. As a result, the predicted threshold pump powers are reduced.