2-μm 1.5-W Optically Pumped Semiconductor Membrane Laser

Abstract

We introduce the first diode-pumped GaSb-based semiconductor membrane laser with a continuous wave (cw) output power of 1.5 W at a center wavelength of 2.08 µm with an optical-to-optical efficiency of 11.7 % and thermal resistance of 0.74 K/W. It features a broad tunability over 117 nm, achieved using a 3-mm birefringent quartz crystal in Brewster configuration. This tuning range is currently limited by the dielectric cavity mirrors. The laser beam quality, indicated by an M 2 < 1.45, remains excellent across all output powers. Unlike diodepumped ion-doped solid-state lasers, this semiconductor laser offers full wavelength flexibility through InGaSb quantum well (QW) bandgap engineering in the short-wave-infrared (SWIR) regime. The 1.2-µm thick membrane gain chip with 12 InGaSb QWs is directly bonded on a silicon carbide heatspreader. This type of laser is also referred to as a MECSEL (Membrane External Cavity Surface Emitting Laser) which can support high-power operation in the SWIR regime due to their excellent heat dissipation. We developed new processing techniques to showcase the promising results for MECSEL in the GaSb-based material system.