Optical bistability in coupled-cavity semiconductor lasers

Coupled-cavity semiconductor lasers are shown to exhibit bistability when both sections operate in the above-threshold regime. The hysteresis width can be adjusted by controlling the current in the modulator section. The theoretical model is based on a set of generalized rate equations and shows that the bistable behavior is due to nonlinearities associated with above-threshold gain saturation. Experiments are performed using a cleaved-coupled-cavity InGaAsP laser operating at 1.3 μm. The experimental results are in reasonable agreement with the theory.