@article { , title = {Determining small refractive index contrast in chalcogenide-glass pairs at mid-infrared wavelengths}, abstract = {A two-composition thin film (Ge20Sb10Se70/Ge20Sb10Se67S3 atomic\%core/cladding glasses) was fabricated using a hot-fibre-pressing technique in which both glasses follow the same post-fibre processing. A simple approach is proposed that uses normal incidence transmission spectra to determine their refractive index contrast over the wavelength range from 2 to 25 μm with an error of less than \_ 0.002. Using an improved Swanepoel method, the calculated numerical aperture of these two compositions was within \_ 0.011 of that obtained from prism minimum deviation measurements. Results show that introducing 3 atomic \% S into the Ge-Sb-Se glass system lowered the refractive index and blue-shifted the visible optical bandgap, the far-infrared fundamental vibrational absorption bands and the zero-dispersion wavelength.}, doi = {10.1364/OME.9.002022}, eissn = {2159-3930}, issue = {5}, journal = {Optical Materials Express}, pages = {2022-2036}, publicationstatus = {Published}, publisher = {Optical Society of America}, url = {https://nottingham-repository.worktribe.com/output/1724205}, volume = {9}, year = {2019}, author = {Fang, Y. and Furniss, D. and Jayasuriya, D. and Parnell, H. and Crane, R. and Tang, Z.Q. and Barney, E. and Canedy, C.L. and Kim, C.S. and Kim, M. and Merritt, C.D. and Bewley, W.W. and Vurgaftman, I. and Meyer, J.R. and Seddon, A.B. and Benson, T.M.} }