MEASUREMENT OF DIFFERENTIAL GAIN AND LINEWIDTH ENHANCEMENT FACTOR OF 1.5-MU-M STRAINED-QUANTUM-WELL ACTIVE LAYERS

The differential gain a and the linewidth enhancement factor alpha of 1.5-mu strained quantum-well active layers were measured as functions of the carrier density and the wavelength. Both a and alpha of compres sively strained multiple-quantum-well (CS-MQW) active layers reveal a carrier-density dependence which is stronger than that of unstrained m ultiple-quantum-well (MQW) and tensile-strained single-quantum-well (T S-SQW) active layers. The improvement in these parameters is achieved only when the carrier density is low. On the other hand, in the case o f TS-SQW active layers, the carrier density dependence is much smaller , and the differential gain is improved significantly.