72‐W vertical‐external‐cavity surface‐emitting laser with 1180‐nm emission for laser guide star adaptive optics

We report a high‐power optically‐pumped vertical‐external‐cavity surface‐emitting laser emitting at around 1180 nm. The free‐running laser produced 72 W of output power at a heatsink temperature of 0°C and 53 W near room temperature (20°C). The GaAs‐based gain mirror was bonded to a 2‐mm‐thick diamond attached to a TEC‐cooled copper mount in order to enable efficient heat extraction for high‐power operation. Moreover, the spectrum of the laser was narrowed down to 0.06 nm by employing a combination of a birefringent filter and an etalon inside the cavity which yielded a maximum of 19 W at a heatsink temperature of 20°C. The demonstration opens a new perspective for the realisation of sodium laser guide star adaptive optics employing frequency doubling of 1180 nm radiation.