Iodine-doped Ge-As-Se glasses with high purity and low dispersion

It is well known that, the incorporation of halide will improve the optical properties of chalcogenide glasses with a broad transparent range. Here, we investigated the optical properties and structure of Ge-As-Se-I glasses in order to disclose the role of halogen iodine in the formation of chalcogenide glassy network. It was found that, refractive index, zero dispersion wavelength and glass transition temperature Tg decrease with increasing iodine contents, while the cut-off edge (λ_vis) in the shorter wavelength blue-shifts apparently, and the whole transmission range is expanded widely. The glasses show good chemical stability against moisture. The zero dispersion wavelength of the glasses can be decreased to 4.32 μm by iodine-doping. The evolution of Raman spectra of the glasses indicates that, there is no obvious peak of iodine in Ge-As-Se-I glasses and the dominated glassy network are still the (GeSe) heteropolar bonds.