Design of broadband optical gain in GaSb-based heterostructures with asymmetric quantum wells

A design strategy for achieving broadband optical gain in GaSb-based semiconductor heterostructures operating beyond 2 µm is presented. By employing asymmetric GaInSb/AlGaAsSb quantum wells (QWs) of varying thicknesses, a flat and wide gain spectrum is demonstrated. The approach leverages carrier density and transition energy tuning across QWs to access various energy levels at specific current densities. Simulations using "Harold" self-consistent environment predict a full-width at half-maximum (FWHM) gain bandwidth exceeding 340 nm for a structure comprising one 7 nm and three 13 nm-thick QWs. The modelling parameters were validated against experimental data, ensuring a robust framework for gain engineering in broadband amplifiers and superluminescent diodes for mid-infrared applications.