PHOTOINDUCED OPTICAL-ABSORPTION IN BULK AND THIN-FILM YTTRIUM-IRON-GARNET

Photoinduced irreversible change in optical absorption Delta alpha was observed for a bulk single crystal and a thin film of yttrium-iron ga rnet (YIG) over the spectral range 600-2000 nm and over the temperatur e range 80-200 K. It was found that for a bulk specimen the absorption alpha at the wavelength lambda < 850 nm decreased and for alpha at la mbda > 1000 nm it increased after irradiation. The photoinduced Delta alpha of a thin film showed complicated behavior varying with irradiat ing time. Experimental results are discussed within the framework of a simple phenomenological model.