Differential gain and linewidth enhancement factor of 1.5- mu m multiple-quantum-well active layers with and without biaxially compressive strain

The differential gain and the linewidth enhancement factor of 1.5- mu m multiple-quantum-well (MQW) active layers were measured with and without biaxially compressive strain as functions of the wavelength and the carrier density. These parameters of the strained MQW layer reveal stronger carrier-density dependence than those of the unstrained MQW layer. Most significantly, an anomalous increase in the linewidth enhancement factor is observed at high carrier densities. These characteristics are explained by a simple theoretical analysis.>