Polarization bistability in semiconductor lasers with intracavity multiple quantum well saturable absorbers

Because the confinement of carriers in a quantum well constraints the crystal momentum of the carriers near the band edge to directions close to the well normal, the selection rules for conduction to heavy-hole transitions yield a large anisotropy in the absorption cross section. We predict a new type of room-temperature polarization bistability based upon this effect in a semiconductor laser with an intracavity multiple quantum well saturable absorber. Rate equation analyses of the static device characteristics as a function of various parameters are presented, and show that two-mode bistable behavior with large hysteresis is possible over a broad range of conditions. Other modes of operation, including all-optical switching and tristable operation, have been verified by numerical calculation.