Thermally enhanced frequency upconversion in Nd3+-doped fluoroindate glass

Multiphonon assisted frequency upconversion was observed in a Nd3+-doped fl uoroindate glass pumped at 866 nm. A near-infrared upconverted emission at 750 nm with a peculiar linear dependence with the laser intensity was obser ved and explained. The intensity of the upconverted emission experienced a 40-fold enhancement when the sample's temperature was varied from 298 to 49 8 K. A rate equation model that includes light pumping and multiphonon abso rption via thermally coupled electronic excited states of Nd3+ was used, de scribing quite well the experimental results. (C) 2001 American Institute o f Physics.