Mechanisms for the modulation bandwidth enhancement in high-speed GaAs/AlGaAs and InGaAs/GaAs MQW lasers

A detailed comparison is presented between MBE-grown, vertically-compact, high-speed GaAs and strained Insub0.35Gasub0.65As ungraded separate-confinement double heterostructure MQW lasers designed for monolithic integration with MODFET driver circuits. The observed increase in differential gain is sufficient to account for the increased modulation bandwidths of the Insub0.35Gasub0.65As lasers. However, since the damping factor remains almost identical for both devices, the increase in differential gain appears to be offset by a corresponding increase in the nonlinear gain.