Erbium spectral-luminescent characteristics in bromide-fluoride photo-thermo-refractive glasses

Abstract

Subject of Research. The paper presents the study of spectral-luminescent characteristics of erbium ions in bromide- fluoride photo-thermo-refractive glasses with 0.1 mol% of erbium oxide and 1-2 mol% of ytterbium oxide concentration. Such spectroscopic parameters as stimulated emission cross-section of erbium ions at a wavelength of 1.5 microns, the efficiency of energy transfer from ytterbium to erbium ions, and the quantum efficiency are calculated based on the measured absorption spectra of glasses under study. The gain/loss spectra of erbium ions in the infra-red range are calculated for various population inversion values. Methods. Bromide-fluoride photo-thermo-refractive glasses were synthesized in an electric furnace at the temperature of 1480 °C for 5 hours in the air. Judd-Ofelt theory was used for determination of spectroscopic intensity parameters. The amplification spectra were obtained using McCumber theory. Main Results. It was found that the stimulated emission cross-section of erbium ions at a wavelength of 1.5 microns is typical for erbium in silicate glasses. The quantum efficiency of radiation at the same wavelength reached 95 %, and the energy transfer efficiency was 86 %. The gain factor had a positive value when the population inversion parameter was higher than 0.5. Practical Relevance. Bromide-fluoride photo-thermo-refractive glasses activated with erbium and ytterbium ions have spectral-luminescent characteristics comparable with commercial laser silicate glasses. In addition, they allow for recording of highly efficient Bragg gratings. Thus, these glasses can be promising candidates for creating distributed feedback lasers with ultra-narrow spectral lines.