Apart from polycrystalline ceramics, single crystals of garnets, especially yttrium aluminium garnet (YAG) and gadolinium gallium garnet (GGG) have high optical transparency (~85 % at the emission wavelength > 500 nm for YAG and ~80 % at 520 nm for GAGG ) in the visible and near-infrared spectral ranges. This optical transparency makes these materials suitable for optical devices and systems which depend on high optical quality since they allow light transmission with minimum absorption or scattering .