Quantifying Loss Mechanisms in InGaAsP/InP Quantum Dash and Quantum Well Lasers

As quantum dash laser designs gain technological maturity, there is a need to investigate performance limiting factors. We simulate monolithic ridge waveguide quantum dash (QDash) and quantum well (QW) lasers in the InGaAsP/InP-system to investigate the mechanisms limiting device performance at elevated temperatures. Our findings are compared to experimental data obtained for representative devices. We quantify dominant loss mechanisms as a function of injection current density at different temperatures and compare results for QW and QDash structures. We find a variation in relative loss contribution between devices. At higher temperatures we find Auger recombination emerging as the dominant loss mechanism.

I. Motivation

The reduction in temperature-related degradation of InP-based telecommunication laser characteristics has enabled increasingly complex data transmission schemes yielding higher data transport rates over existing network infrastructure. Increased dimensional confinement of the optically active states is one key method that reduces the temperature dependence, while simultaneously improving threshold current density, material and differential gain, and linewidth enhancement factors [1]. Recent quantum dot (QD) and quantum dash (QDash) laser designs further improve these parameters. While outperforming similar multi-quantum well (MQW) devices for threshold and linewidth, improvements to the design are required for high temperature operation [2]. We present modelling of the carrier dynamics to investigate the effect of several loss mechanism in InGaAsP/InP QW and QDash lasers.