Nonlinearities and Dielectric constant of Ge-Se Chalcogenide Glasses

We recorded a transmission spectrum of Ge-Se glasses in the UV-visible range, revealing 80-90% transmission of light at room temperature. The percentage of light absorbed by these glasses is only 15%. The applicability of these glasses for the fabrication of single-mode optical fibre is being pursued by their high transmission and nearly nonexistent normal dispersion, while a small anomalous dispersion drop in the transmission is noticed at 720 nm in the UV-visible region. Drop in transmission at higher wavelength is explained in terms of absorption/photodarkening effect. Analysis of prepared glasses reveals direct band-gap material; thus, these materials can be used directly in fibre laser preparation. The refractive index obtained from spectra is modelled by Cauchy expression, and it is valid up to 700nm; beyond 700nm, wavelength increase in refractive index is modelled by poly4. Dielectric characteristics are examined and assessed. Ge-Se glasses have a decreasing dielectric constant as the band gap widens, indicating a decreasing trend in dielectric constant with increasing frequency.