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

Abstract: A design strategy for achieving broadband optical gain in GaSb-based semiconductor amplifiers operating beyond 2 \mu m 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 designing broadband amplifiers and superluminescent diodes for mid-infrared applications.