Theory and Optimization of 1.3-μm Metamorphic Quantum Well Lasers

The use of InGaAs metamorphic buffer layers (MBLs) to facilitate the growth of lattice-mismatched heterostructures constitutes a novel approach to developing GaAs-based long-wavelength semiconductor lasers. Such devices are attractive since they approach the improved electronic and optical confinement associated with GaAs-based materials. As a result, GaAs-based metamorphic devices can be expected to have improved high-temperature performance compared with equivalent InP-based devices, due to the improved carrier confinement in the quantum wells (QWs). We present a theoretical study of GaAs-based 1.3-mu m AlInGaAs QW lasers grown on InGaAs MBLs. We demonstrate that an optimized single or double QW 1.3-mu m metamorphic device offers low threshold current density and high differential gain, both of which compare favorably with InP-based devices. Overall, our analysis confirms and quantifies the potential of 1.3-mu m metamorphic QW lasers for the development of GaAs-based long-wavelength semiconductor lasers, and also provides guidelines for the design of optimized devices.