Characterising refractive index dispersion in chalcogenide glasses

Abstract

Much effort has been devoted to the study of glasses that contain the chalcogen elements (sulfur, selenium and tellurium) for photonics' applications out to MIR wavelengths. In this paper we describe some techniques for determining the refractive index dispersion characteristics of these glasses. Knowledge of material dispersion is critical in delivering step-index fibres including with high numerical aperture for mid-infrared supercontinuum generation.

Determining the refractive index dispersion and thickness of hot-pressed chalcogenide thin films from an improved Swanepoel method

“…The refractive indices of Ge 16 As 24 Se 15.5 Te 44.5 and As 40 Se 60 from the present thin film measurements, a prism minimum deviation measurement (Fang et al 2016) and ellipsometry are shown in Fig. 7.…”

“…A hot-pressing technique was developed to prepare thin films of chalcogenide glass; this involved the hot-pressing of circa 20 mm lengths of fibre, with a nominal diameter of 250 lm, using the hot-press previously described in Fang et al (2016) (ICTON): Seddon et al (2006), Abdel-Moneim et al (2015). The as-annealed preforms (*10 mm diameter and *70 mm length) of Ge 16 As 24 Se 15.5 Te 44.5 and As 40 Se 60 , prepared as in Sect.…”

“…Techniques commonly used for refractive index measurement include the modelling of transmission or reflection spectroscopic data (Swanepoel 1985;Marquez et al 1998), spectroscopic ellipsometry (Orava et al 2009;Wang et al 2017), prism coupling (Carlie et al 2011), grating coupling (Laniel et al 2003), and the measurement of the minimum deviation angle of light passing through a prism (Fang et al 2016). Several of these techniques require intensive sample preparation, are time consuming, and are costly to conduct.…”