Improved Push–Pull Polarization Modulation Using Coupled Quantum-Well Structures

Recently, we proposed a push-pull polarization-modulation scheme based on multiple repetitions of two InGaAlAs-InAlAs coupled quantum-well (CQW) structures. Additional numerical simulations showed one of the two CQW structures to be quite sensitive to layer thickness and compositional variations. Consequently, it would be challenging to reliably grow polarization modulators using this structure. Here, using the effective-mass envelope-function approximation, we design a more robust CQW structure to replace the sensitive one, and we also make improvements to the less sensitive of the two original structures