Theoretical analysis of polarization bistability in vertical cavity surface emitting semiconductor lasers

The polarization bistability of vertical cavity surface emitting lasers under external optical injection is analyzed theoretically. It is found that on the condition where the optical gain is blue-shifted relative to the cavity mode, the bistable characteristics of VCSEL's can be improved significantly: (1) low optical power of the external injection light is required, (2) the influence of self-heating effects is minimized, and (3) wide bistable hysteresis loop width can be maintained. Furthermore, it is also shown that the reflectivity of Bragg reflectors should also be optimized to improve the performance of VCSEL's as bistable switches.