Measurement of differential gain and linewidth enhancement factor of 1.5-μm strained quantum-well active layers

The differential gain a and the linewidth enhancement factor α of 1.5-μm strained quantum well active layers mere measured as functions of the carrier density and the wavelength. Both a and α of compressively strained multiple-quantum-well (CS-MQW) active layers reveal a carrier-density dependence which is stronger than that of unstrained multiple quantum-well (MQW) and tensile-strained single-quantum-well (TS-SQW) active layers. The improvement in these parameters is achieved only when the carrier density is low. On the other hand, in the case of TS-SQW active layers, the carrier density dependence is much smaller, and the differential gain is improved significantly