Upconversion luminescence in Cr3+:YAG single crystal under infrared excitation

Abstract

The present work concerns the upconversion luminescence in Cr3+:YAG single crystal under infrared laser irradiation. During the experiment, 404 nm, 808 nm, 980 nm, and 1064 nm laser excitation sources in range of −150 °C–600 °C were employed. A strong red light emission was detected in the bulk of the samples under the infrared excitation. The red emission originated from 4T2g→4A2g transition of Cr3+ ions and are only observed at temperatures higher than 150 °C; the profile of the emission curve is Gaussian-type with maxima at 500 °C, 600 °C, and 620 °C for λexc 808 nm, 980 nm, and 1064 nm respectively. This is attributable to the high-temperature nature of the upconversion luminescence, where the energy gap between the energy of a laser photon and the 4T2g state is compensated by simultaneous absorption of two photons.