Effects of pressure on optically pumped GaSb, InAs, and InSb lasers

The pressure dependence of the energy gap has been determined at 63 and 77°K for GaSb, InAs, and InSb by tuning their laser-emission frequencies with hydrostatic pressures up to 8 kbar. The pressure variation of mode frequency and refractive index has also been measured for each semiconductor. The laser threshold and emission intensity are essentially independent of pressure in GaSb and InAs. For InSb, however, the application of pressure dramatically decreases the threshold and increases both spontaneous and stimulated emission. A number of experiments have been performed to determine the cause of these pressure effects. The data are consistent with a mechanism involving nonradiative recombination between nearly overlapping bandtails within the energy gap which separate with pressure.