Operating Characteristic Simulation of High-Power Broad-Stripe Quantum-Well Semiconductor Traveling Wave Amplifiers

To design an optimized high-power semiconductor traveling wave amplifier (TWA), it is important to study the parameter dependencies of a TWA on its waveguide structure, material properties, and operating conditions. Since the degradation of the output beam profile in a broad-stripe TWA is often observed in practice, two-dimensional models employing the beam propagation method (BPM) and the effective index method have been widely used [1-2]. These models are usually based on a linearization of basic material properties. For high-power TWAs, the operating current is several times larger than the threshold current of a corresponding laser diode. Linear approximations are under these conditions no longer valid. In this paper, we consider nonlinear material properties in a self-consistent BPM model. Nonlinear gain and residual facet reflectivities are found to greatly influence the operating characteristics of the devices.