Theory of carrier gain dynamics in InGaAs/AlGaAs strained-layer single-quantum-well diode lasers

Abstract

Calculations of the femtosecond gain dynamics in InGaAs/AlGaAs strained-layer single-quantum-well diode lasers are presented and compared to experiments which use a novel multiple-wavelength pump probe technique. We develop a detailed theoretical model for the gain dynamics in a quantum well laser diode structure to aid in the interpretation of gain dynamics induced by both interband absorption and stimulated emission of photons. In the model, transient gain and differential transmission are computed in a multiband effective mass model including biaxial strain, valence subband mixing, and scattering both within and between subbands. The transient photogeneration of electron-hole pairs by the pump pulse and subsequent relaxation of carriers by both polar optical phonon scattering and carrier-carrier scattering are calculated within a Boltzmann equation framework. A relaxation approximation for the carrier-carrier scattering is made making the coupled Boltzmann equations an effective one dimensional model which are then solved using an adaptive Runge-Kutta technique rather than a more computationally intensive Monte Carlo approach.