OPTICAL SPECTROSCOPY OF ER3-DOPED FLUOROINDATE GLASSES( AND YB3+ CO)

Optical absorption, Stokes, and anti-Stokes photoluminescence were per formed on Er3+-Yb3+ co-doped fluoroindate glasses. For compounds prepa red with a fixed 2 mol % ErF3 concentration and YbF3 contents ranging from 0 to 8 mol %, important upconversion processes were observed as a function of temperature and photon excitation energy. Based on the ex perimental data, two mechanisms for the upconversion (or anti-Stokes p hotoluminescence) processes were identified and analyzed in detail. At high Yb contents, the upconversion mechanisms are mostly determined b y the population of the F-2(5/2) levels of Yb3+ ions (or I-4(11/2) lev els of Er3+ ions, by energy transfer) regardless of the photon excitat ion energy and temperature of measurement. Moreover, green and red lig ht emission have similar intensities when a large Yb3+ content is pres ent. (C) 1998 American Institute of Physics.