Barrier composition dependence of differential gain and external differential quantum efficiency in 1.3-/spl mu/m strained-layer multiquantum-well lasers

Dependence of the differential gain and the external differential quantum efficiency on the composition of InGaAsP barrier layers were investigated for 1.3 /spl mu/m InGaAsP-InGaAsP compressively strained layer (SL) multiquantum well (MQW) lasers. In this investigation, we compared between SL-MQW lasers and unstrained MQW lasers having the same well thicknesses and the same emitting wavelength in order to clarify the effect of strain for each barrier composition. As a result It has been found that the barrier composition has large influence on the differential gain and the external differential quantum efficiency in the SL-MQW lasers. Narrower band-gap barrier means little effect of strain on the differential gain due to the electron overflow from a well layer, while wider band-gap barrier means degradation in the differential gain and the external differential quantum efficiency due to the nonuniform injection of hole into a well layer. In this experiment, the barrier composition of 1.05 /spl mu/m is suitable for 1.3 /spl mu/m InGaAsP-InGaAsP SL-MQW lasers to realize large differential gain and high external differential quantum efficiency simultaneously.