Rate-equation-based laser models with a single solution regime

Even with the use of variable transformations, quantum-well (QW)-laser models based on the standard rate equations and a linear gain-saturation term can possess multiple dc solution regimes for nonnegative values of injection current. In this paper, we demonstrate analytically that rate-equation-based models that employ more realistic gain-saturation terms can be transformed so that they do indeed possess a unique solution regime. We also present circuit-level implementations of these models suitable for use in SPICE.