Structures with variable dimensionality of electronic states for unipolar lasers

We review our study aimed at the creation of a unipolar laser with the efficient suppression of nonradiative relaxation between the laser subbands owing to strongly asymmetric-in-height barriers surrounding an active element. The asymmetry of the barriers causes the existence of a lower laser subband only within a narrow region of in-plane momenta. In such a way, one-phonon relaxation between the laser subbands can be significantly suppressed.