Semiconductor membrane microchip laser

We demonstrate a semiconductor microchip membrane external-cavity surface-emitting laser (MECSEL). This compact type of laser consists solely of a semiconductor gain region present as a micron-thin membrane, sandwiched between two transparent heat spreaders. The outer facets of the microchip MECSEL presented in this work have a highly reflective coating, which assembles the laser's plane-parallel solid-state cavity with a total length of just ∼ 1 mm. One of the coatings has a slightly reduced reflectivity to act as an outcoupling mirror. The membrane microchip laser is optically pumped with a standard fiber-coupled diode laser module emitting at 808 nm and stabilizes itself due to the occurrance of a thermal lens. More than one watt of continuous wave output power around 1123 nm and a record value in slope efficiency of ∼ 51.4 % with MECSELs, while maintaining excellent beam quality (TEM₀₀, <i>M</i>² < 1.05), is demonstrated. Important properties of semiconductor lasers such as the efficiency, beam quality, and polarization were investigated. Further, the laser setup itself was used to characterize the thermal lens and its dependence on the absorbed pump power. Such systems represent an attractive solution, when high-power output at customizable emission wavelength with excellent beam quality is needed in combination with a very compact built size.