A rate equation model of asymmetric multiple quantum-well lasers

Abstract

This paper gives a description of a rate equation model to simulate the steady-state and frequency response characteristics of asymmetric multiple quantum well (AMQW) lasers using several different methods. AMQW lasers consist of several quantum wells of different widths or compositions designed to achieve a broad net gain profile for improved wavelength tuning. The position of the quantum wells relative to the p-side of the device plays an important role in the steady-state characteristics due to a significant nonuniform carrier distribution across the active region. Simulations of the carrier distribution and the onset of simultaneous lasing for certain structures are demonstrated using this model. Appropriate values for the distributed material loss and tunneling times were determined here by fitting the model output to measurements of the transition cavity length for a number of AMQW lasers. As well, comparison of different calculation methods demonstrates it is more appropriate to use a numerical analysis of the laser rate equations rather than analytic equations when modeling the frequency response of these structures. However, an analytic equation for the resonance frequency was found that fit well with numerical simulations of several different AMQW laser structures.