Optical transitions and frequency upconversion emission of Er3+ ions in Ga2S3–GeS2–La2S3 glasses

Abstract

Spectroscopic properties of Er3+ in Ga2S3–GeS2–La2S3 glasses are investigated on the basis of the spontaneous emission probabilities calculated by the use of the Judd–Ofelt theory and lifetime data. Frequency upconversion spectra are also measured with excitation at 800 and 980 nm. The spontaneous emission probabilities are much larger than those of the other glass systems such as oxides and fluorides. This is mainly attributed to the large refractive indices of the sulfide glasses. The quantum efficiencies of I11/24 and F9/24 levels are comparable or larger than the typical values of Er3+ in a fluoride glass. This is a consequence of the large spontaneous emission probabilities and low phonon energies of the sulfide glasses. However, the quantum efficiency of the S3/24 level is less than one-half of the value in the fluoride glass. The nonradiative transition probability of the S3/24 level is much larger than the value which is evaluated from the multiphonon relaxation theory. This suggests the presence of the other nonradiative relaxation process in addition to the multiphonon relaxation. This process is considered to be the energy transfer from the excited Er3+ to the band-gap excitation of the matrix glass. In upconversion spectra, the 497 nm emission from the F7/24 level is observed in addition to the red (665 nm) and the green (533 and 552 nm) emission bands.

Enhancement of up-conversion luminescence in Zn2SiO4:Yb3+, Er3+ by co-doping with Li+ or Bi3+

“…3, the fitted slopes are 1.95 and 1.56 for the green and red emissions, respectively, indicating that the two emissions both exhibit two-photon processes. Possible up-conversion mechanisms [29][30][31][32][33] are discussed based on the simplified energy levels of Er 3+ and Yb 3+ , presented in Fig. 4.…”

Host dependent frequency upconversion of Er3+-doped oxyfluoride tellurite glasses

“…Many trivalent rare-earth ions such as Er 3+ , Tm 3+ , Ho 3+ , Pr 3+ , and Nd 3+ were doped as absorption and emission centers in glass hosts. Among the rare-earth ions, Er 3+ is the most popular as well as one of most efficient ions [3][4][5][6]. Glass materials are attractive as hosts because planar waveguides and optical fibers can be fabricated easily compared to crystalline materials.…”

Photoluminescence properties in Pr3+-doped chalcogenide glass

“…Chalcogenide glasses are among the promising candidate for the active optical devices with high efficiency because of their low-phonon-energy property [4]. This property, along with their high refractive indices, attracts intensive studies on sulphide [5][6][7][8] and chalcohalide glasses [9] such as rare-earth-ion-doped Ga 2 S 3 -GeS 2 -La 2 S 3 , which are found to be relatively easily vitrified [10]. Many of the studies on these glasses put their emphasis on the upconversion emission properties.…”