High power continuous wave operation of a GaSb-based VECSEL emitting near 2.3 µm

We report on a GaSb-based optically pumped vertical external cavity surface-emitting laser (VECSEL) operating near 2.3 µm. The epitaxial layer structure has been analyzed by high-resolution X-Ray diffraction, as well as reflectivity and photoluminescence (PL) spectroscopy. PL recorded from the side facet of a cleaved sample is used to determine the true quantum well emission spectrum. CW laser operation is observed at room temperature for substrate-side-down mounted samples even without thinning the substrate. Laser output power is significantly increased to >300 mW when using an intra-cavity polycrystalline diamond heat spreader bonded to the semiconductor chip. The temperature-dependence of the VECSEL characteristics is explained by changes in the relative alignment of the cavity resonance and the gain spectrum.