Abstract

Holmium lasers are the main sources of coherent 2.1 µm radiation. This spectral region is attractive for many reasons: due to reasonable absorption in water, this radiation is eye-safe and suitable for some medical applications; at the same time, due to the small absorption in the atmosphere, it can be used for applications requiring its propagation in free space, such as optical communications or LIDAR. Especially in this case, however, the ability to accurately choose the laser wavelength is important. If we do not use any dispersive element to set the operation wavelength, the laser will generate near the local maxima of the emission cross-section, and its possible tuning is affected by the width of the emission lines. The used matrix has an influence on these parameters. Standard matrices for Ho lasers include garnets, mainly YAG and LuAG, which have excellent optomechanical and thermomechanical properties.[1] This also includes the mixed GGAG crystal.[2] Based on the good experience with this material and with the goal to find other garnet matrices suitable for Ho³⁺ -doping, we investigated a series of mixed garnets of the type (Gd_xLu_y)(Ga_aSc_bAl_c)O₁₂ prepared by the micro-pulling-down (µ-PD) method.[3]

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