Phosphate and fluoride phosphate optical glasses - properties, structure and applications

摘要

Our investigations of phosphate and fluoride phosphate optical glasses started in 1976. The aim was the development of optical glasses with high positive anomalous partial dispersions, making them desirable for lens designs that reduce the secondary spectrum in high performance optics to substitute for CaF2 single crystals. A large variety of glasses have been prepared and investigated. The effect of cations and fluorine in phosphates on the refractive index, dispersion, thermal and chemical properties was studied. It was found that fluoride phosphate glasses based on AlF3, MF2, and P2O5, have the required optical properties. Fluor crown and phosphate crown optical glasses were developed. The structure and properties of these glasses depend mainly on the molar relation between fluorides and phosphates, which can be varied in a wide range between pure fluoroaluminate and phosphate glasses. The structure model can be described as chains of Al(F,O)(6) octahedra, bonding by mono- and diphosphate groups and cations. Their intrinsic transparency in the vacuum UV range is comparable with those of silica, and CaF2. The absorption coefficients of possible trace impurities in different redox states were determined. The effect of UV lamp, UV laser, x-ray radiation, and laser writing of waveguides was studied. Together with colleagues from physics departments, we developed efficient laser and amplifier glasses with Nd3+, Er3+, and Yb3+. The POLARIS (petawatt optical laser amplifier for radiation intensive experiments) system is based on a fluoride phosphate glass doped with Yb3+, which is used as the active medium, pumped by light from laser diodes. Photoluminescence in glasses doped with ions in s(2) configuration (Sn2+, Pb2+, As3+, Sb3+), d(0) configuration (Te4+, Nb5+, Ta5+, Mo6+, W6+), or d(10) configuration (Ag+, Cu+), which absorb strongly in the UV, has been demonstrated mainly in the UV and blue-green region. Efficient visible photoluminescence with different lifetimes was found in Mn2+ (3d(5)), and in rare earth (f(n)) doped glasses (Ce3+, Pr3+, Sm3+, Eu2+, Eu3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+), which can be used for various applications.