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

Abstract 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 4f25d 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 30 K 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.