Fabrication of Yb3+,Er3+:YAG transparent ceramics and study of its 1.5 μm fluorescence spectrum

Abstract

5at%Yb3+,2at％Er3+:YAG transparent ceramics possessing a high transmittance was sintered at 1760℃ for 30 h by solid-state method and vacuum sintering technique. The sample exhibited pore-free structure and had no secondary phase in the grain boundary and in the grain, as observed in the SEM photograph. The sample's absorption and fluorescent spectra show that the Yb3+ ions have a high absorption coefficient at 940nm. The decay life-time at the 1030nm wavelength is only 0.274 ms and the initial intensity has an ascending tendency in the fluorescent life-time curve at the wavelength range of 1.5 μm, both of which demonstrate the existence of energy transfer from Er3+ ions to Yb3+ ions. The life-time and stimulated emission cross section of electronic transition between some levels were calculated with the intensity parameter Ωλ of Er3+ acquired from Judd-ofelt theory. The experimental results of the spectrum parameters (the emission cross section and fluorescent life-time)of Er3+ ions in the wavelength range of 1.5μm are the same as the results of the Judd-Ofelt theory. The transition between 4I13/2 and 4I15/2 simultaneously has a large stimulated emission cross section, fluorescence ratio and upper level life-time relative to the other energy level transitions of the sample, which makes the laser output of Er,Yb:YAG transparent ceramics in the wavelength range of 1.5 μm, the eye-safe wavelength range, possible.