Method of determining differential gain coefficient for bistable semiconductor laser diodes

Analytical expressions are obtained for the output power and bias current at switch on and switch off for absorptive bistable semiconductor laser diodes. Manipulation of these expressions yielded a simple analytical expression for the product of the carrier lifetime τ2 and the differential gain σ2 in the absorber region in terms of the hysteresis width and the switch-off output power of the measured L–I characteristics. Experiments on a number of absorptive bistable devices indicated a mean value of 4.1 × 10−16cm2 for σ2.