Far-infrared laser generation from an optically pumped single quantum well structure

An optically pumped far-infrared (FIR) intersubband laser generator is proposed in which the continuum states above an Al/sub 0.2/Ga/sub 0.8/As-GaAs-Al/sub 0.2/Ga/sub 0.8/As single quantum well structure with a well width of L=170 /spl Aring/ serve as the highest level in a four-level laser system. This simple structure has been designed to take advantage of the electro-phonon resonance (EPR) effect induced by electron interactions with longitudinal optical (LO) phonons in GaAs-based two-dimensional semiconductor systems (2DSSs), in achieving population inversion between the second and third electronic subbands. The design allows much greater flexibility in the choice of pumping sources and simplifies considerably the device fabrication. The electronic subband structure of the proposed FIR intersubband laser device has been obtained from a self-consistent calculation via solving coupled Schrodinger and Poisson equations.