Complex Er-doped selenium-based chalcogenides in the far-infrared region: a structural bonding arrangement study

Abstract

Selenium-based chalcogenide glasses show tremendous infrared transmission in the 2-15 µm region, and these amorphous glasses could be easily formed into optical devices i.e. optical fibers and lenses, owing to their good thermo-mechanical properties. Even though the phonon energy for tellurium-based glasses is on the lower side, still, selenium-based glasses are worthwhile for mid to long-wavelength infrared emissions. Here, we have developed Er-doped Selenium-based, Ge17Sb8Se75-xErx where x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0, chalcogenides through conventional melting and quenching method for possible mid to far-infrared applications. Far-infrared transmission spectra of the synthesized chalcogenides are obtained at room temperature in the spectral range of 35-450 cm-1. The bonding arrangements in the synthesized chalcogenides are investigated as a function of composition. It has been found that with the addition of Er content, the far-infrared transmission spectra shift toward the lower wavenumber side. The experimental results are correlated with the theoretically calculated parameters like relative probability, bond energy, wave number, force constant etc. The obtained results provide insight into understanding the synthesized chalcogenides' optical behavior, which is vital for designing the optical components operated on mid-infrared to far-infrared regions.