High Speed InGaAs/GaAs Strained Multiple Quantum Well Ridge Waveguide Lasers with Low Damping

Abstract

The enhancement in differential gain in quantum well lasers, due to the quantization of the density of states, has been predicted to lead to a corresponding increase in modulation bandwidth in these lasers compared to bulk devices. Further, the reduction of subband nonparabolicity and the lowering of the density of states in the valence band with the introduction of strain in the active layer is expected to increase the modulation bandwidth even more [1]. To date the largest modulation bandwidth reported for unstrained GaAs/AIGaAs [2] and strained InGaAs/GaAs [3,4] single quantum well (SQW) lasers is about 6 GHz. Having multiple quantum wells for the active area improves the differential gain and the optical confinement factor leading to a corresponding increase in the bandwidth over the single quantum well casa.