Wavelength selection, spatial filtering and polarization control of an Er:YAG laser cavity by resonant-grating mirror

Summary form only given. Er:YAG crystals are good candidates for eye-safe solid-state lasers with output pulses energy in the mJ range, which are required for applications in atmospheric propagation such as active imaging, lidar and wind mapping. Er:YAG crystals can emit at 1645 nm or 1617 nm. The laser emission of Er:YAG naturally occurs at 1645 nm and is unpolarized. In addition, the required high incident pump powers in quasi-three-levels laser such as Er:YAG could lead to a poor beam quality factor (M²) because of well-known thermal effects in rod lasers. Some applications may require emission at 1617 nm with a good M² factor for long range sensing, as well as linearly polarized output beams for pollutant probing [1]. Therefore, a basic Er:YAG cavity could be provided with an intra-cavity etalon for wavelength selection [2], a reflective polarizer for polarization control, and a pinhole for spatial filtering. In this contribution, we report on a resonant-grating mirror (Fig. 1 left) which can be used to fullfil these three functions, hence simplifying the laser setup [3].