2.5 µm semiconductor disk laser with 130 nm tuning range

In this study we report a GaSb-based optically-pumped semiconductor disk laser emitting the radiation tunable over 130 nm around 2.5 μm. The semiconductor structure was grown using a solid-source molecular beam epitaxy on an n-GaSb wafer (100) in a single epitaxial run. The structure consists of distributed Bragg reflector (DBR) with 21.5 pairs of GaSb/AlAsSb and a gain section with 15 strained Inο^sGaAsSb quantum-wells (QWs) surrounded by 20 nm thick Al0.3GaAsSb barriers. 9.5 nm thick QWs were arranged in groups of three and embedded in Al05GaAsSb waveguide which provides the dominant pump absorption. The gain structure was closed with a lattice-matched AlAsSb window layer to ensure good carrier confinement covered by a thin GaSb cap layer preventing oxidation. Layer thicknesses were selected to form a 3λ micro-cavity between the DBR and the AlAsSb-window layer with QW groups located at the antinodes of the standing-wave optical field.