Preparation of high-purity Pr3+ doped Ge-As-Se-In-I glasses for active mid-infrared optics

The multi-stage method for the synthesis of high-purity Ge-As-Se-In-I glasses doped with Pr3+ ions is developed. It is based on the chemical distillation purification of glass-forming melt and the chemical transport reactions for purification and vacuum loading of indium. The level of purity of glasses, synthesized by this method, is higher in comparison with the traditional direct melting method for glass synthesis. The high-purity Pr3+-doped Ge-As-Se-In and Pr3+-doped Ge-As-Se-In-I glass samples are prepared; the optical, thermal and luminescent properties are investigated. The purest host glass samples, obtained by the multi-stage purification techniques, contain a low concentration of limiting impurities: hydrogen − ≤0.05 ppm (wt) and oxygen − ≤0.1 ppm (wt), that is, at present, the best result for multi-component chalcogenide glasses for mid-IR active fibers. The samples of Pr3+-doped Ge-As-Se-In glass fibers have the minimum optical losses of 0.58 dB/m at the wavelength of 2.72 μm and exhibit an intense broadband luminescence in the spectral range of 3.5-5.5 μm, with a maximum shifted to longer wavelengths as compared with the bulk samples.