Thermal lensing effects in Pr³⁺-doped ZnO-CdO-SiO<inf>2</inf>luminescent glass

Optical absorption, photoluminescence and fluorescence decay time of Pr3+in a ZnO-CdO-SiO2glass were measured in the 400-800 nm range. Under continuous (CW) laser excitation the characteristics of thermal lensing (TL) were measured at room temperature, under resonant and non-resonant conditions. Our results are analysed based on a theoretical model for CW laser induced thermal lensing under a gaussian-beam approximation. The effects of the power input and the response time for TL are explained in terms of the thermal properties of the glass host, for non-resonant excitation, and in terms of the coupling of rare earth ions to the local vibrations for resonant excitations. We also report, for the first time, the observation of laser induced permanent changes in the refractive index of bulk rare earth doped oxide glasses, under non-resonant excitation conditions.