Design of a new asymmetric waveguide in InP-Based multiquantum well laser

Today, electron leakage in InP-based separate confinement laser diode has a serious effect on device performance. Control of electron leakage current is the aim of many studies in semiconductor laser industry. In this study, for the first time, a new asymmetric waveguide structure with n-interlayer for a 1.325 µm InP-based laser diode with InGaAsP multi-quantum well is proposed and theoretically analyzed using the PICS3D simulation software. The simulator self-consistently combines the 3D simulation of carrier transport, self-heating, and optical waveguiding. Through the simulation, the optical and electrical performances of laser diodes with symmetric and asymmetric waveguides are studied. Numerical simulation reveals that the asymmetric structure exhibits higher output light power, slope efficiency, emission intensity, and series resistance, as well as lower electron leakage and threshold current density under identical conditions, compared with the symmetric structure. The performances are greatly enhanced in the laser diode with asymmetric waveguide design because of the improved radiative stimulated recombination rate, declined non-radiative Auger recombination rate and decreased overlap between the optical wave and the p-doped layer.