Ultraviolet hollow-core waveguides with sub-unitary index chalcogenide cladding

The chalcogenide semiconductor antimony telluride exhibits a sub-unitary refractive index as low as 0.7 at mid- to near-UV wavelengths between 220 and 400 nm, with the spectral width of the sub-unitary band, minimum index and associated extinction coefficient being controllable functions of alloy composition. As such it can enable step-index hollow-core optical waveguiding at ultraviolet wavelengths and thereby, for example, spectroscopic and sensing applications wherein the confinement of light and a fluid analyte in the same core volume maximizes sensitivity, thereby limiting required interaction lengths to as little as a few wavelengths.