Color centers in yttrium-aluminum and yttrium-erbium-aluminum garnet crystals

Color centers were generated by the pump lamp radiation in yttrium-erbium-aluminum garnet crystals used in lasers. An investigation of unactivated yttrium-aluminium garnet crystals indicated that the color centers were not associated with the activator ions but formed in the host matrix. Two types of color center were observed and their appearance was governed by the conditions during crystal growth. The number of color centers increased under the action of the pump lamp radiation. A correlation was found between the scattering of light in crystals and the intensity of the absorption by type I color centers.