Comparision of InGaAs absorptive grating structures in 1.55 /spl mu/m InGaAsP/InP strained MQW gain-coupled DFB lasers

In gain-coupled (GC) distributed-feedback (DFB) lasers of absorptive grating type, the device characteristics depend very much on the absorptive grating configuration such as duty cycle, layer thickness, conduction type, and material composition. We have fabricated 1.55 /spl mu/m InGaAsP/InP strained multiple quantum well (MQW) DFB lasers having different absorptive grating thickness and different conduction type. Lasing characteristics of these lasers were compared with regard to coupling coefficients and absorption saturation. Through net gain measurement, information useful for designing and optimizing the absorptive grating was obtained.