Significant blue-shift in photoluminescence excitation spectra of Nd3+:LaF3 potential laser medium at low-temperature

Temperature-dependent optical properties of bulk Nd3+:LaF3 crystals are reported. A blue-shift in the photoluminescence excitation (PLE) spectrum is observed at 30 K. The 173.2-nm emission peak wavelength at 300 K shifted to 172.8 nm at 30 K, consistent with the 6-nm blue-shift in transmission edge and 2437-cm(-1) increase in the lowest energy level of the 4f(2)5d configuration. Thermal broadening of the 5d-4f emission bands with increasing temperature is also observed as the dip at around 178.5 nm present at 30K disappears at 300 K. A smaller spectral overlap between the PLE and emission spectra is observed as temperature is decreased. Our results suggest that absorption cross-section at the peak fluorescence wavelength is expected to decrease at 30 K. (C) 2015 Elsevier B.V. All rights reserved.