Broadband 2.4 μm superluminescent GaInAsSb/AlGaAsSb quantum well diodes for optical sensing of biomolecules

High power, high radiance, broadband light sources emitting in the 2.0-2.5 μm wavelength range are important for optical sensing of biomolecules such as glucose in aqueous solutions. Here we demonstrate and analyze superluminescent diodes with output centered at 2.4 μm (range ~2.2-2.5 μm) from GaInAsSb/AlGaAsSb quantum wells in a separate confinement structure. Pulsed wave output of 1 mW (38 kW/cm²/sr) is achieved at room temperature for 40μm × 2mm devices. Superluminescence is evidenced in superlinear increase in emission, spectral narrowing, and angular narrowing of light output with increasing current injection. Optical output is analyzed and modeled with rate equations. Potential routes for future improvements are explored, such as additional Auger suppression and photonic mode engineering.