Broadband continuous-wave GaSb-based superluminescent diodes emitting at 2.1 <i>μ</i>m

We report development of GaSb-based superluminescent diodes (SLDs) emitting around 2.1 μm wavelength for applications in sensing and non-destructive imaging benefitting from broad and smooth spectra with low modulation depth ripples. Record-large spectral bandwidth is reported by exploiting an asymmetric type-I double quantum well InGaSb/AlGaAsSb active region. Preventing lasing from such gain structures while enhancing the amplified stimulated emission and mitigating the spectral modulation is essential. To this end, we employ J-waveguide chip architecture and perform a systematic study of the influence of facet’s reflectivity orienting the SLD chip’s p-side in upward direction. Broad emission with a full width at half maximum spectrum of ≥140 nm [corresponds to ∼1 mW in continuous wave (CW) power] and minimal ripples is reported, which is a nearly twofold increase in emission bandwidth compared to the previous reports in this spectral region. We also report SLD devices that can deliver a maximum output power of 56 mW for a limited bandwidth of ∼45 nm at room temperature in CW operation.