Impact of temperature on optical spectra and up-conversion phenomena in (Lu0.3Gd0.7)2SiO5 crystals single doped with Er3+ and co-doped with Er3+ and Yb3

Optical absorption and luminescence spectra were recorded at different temperatures for the Czochralski grown crystals of Lu2SiO5-Gd2SiO5 solid solution (LGSO) single doped with Er3+ and double-doped with Er3+ and Yb3+. Optical anisotropy and intensities of Er3+ transitions in LGSO were determined from analysis of room temperature polarized absorption spectra. The crystal field splitting of multiplets and linewidths of Er3+ transitions were derived from low-temperature 6 K absorption and luminescence spectra. Spectra of the Er3+ luminescence excited at 380 nm and of up-converted luminescence excited at 803 nm and 975 nm were recorded for samples with different Yb3+ concentration as a function of temperature between 300 K and 775 K. Thermographic parameters of LGSO:0.5%Er,5%Yb sample derived for FIR (2H11/2/4S3/2) are comparable to those observed in other hosts co-doped with Er and Yb ions, corroborating suitability of this system for the purpose of optical thermometry. For all samples studied the relative thermographic sensitivity Sr(max) values for the 4S3/2/4F9/2, 4F7/2/4S3/2 and 4F7/2/4F9/2 pairs are smaller as compared to 2H11/2/4S3/2 pair but they occur at higher temperatures and therefore may be of interest for specific applications. •Examining the Er,Yb co-doping LGSO solid solutions relevant for numerous applications.•Investigation of the erbium energy levels employing low-temperature 6 K experiments.•Wide-range thermally-induced changes of Er3+ involved spectroscopic features in LGSO crystals.•Study on thermographic parameters important for potential optical sensors.