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 tau ₂ and the differential gain sigma ₂ 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*10¹⁶ cm² for sigma ₂.