arXiv subjects

Jonathan C. Knight

Publications and source records attributed to Jonathan C. Knight.

2 recordsLinked to original sources

arXiv2024

Optical absorption spectrum reveals gaseous chlorine in anti-resonant hollow core fibres

We have observed unexpected spectral attenuation of ultraviolet light in freshly drawn hollow core optical fibres. When the fibre ends are left open to atmosphere, this loss feature dissipates over time. The loss matches the absorption spectrum of gaseous (molecular) chlorine and, given enough time, the transmission spectrum of the fibre recovers to that expected from the morphological structure of the fibre. Our measurements indicate an initial chlorine concentration of 0.45 $\mu$ mol/cm$^{3}$ in the hollow core, equivalent to 1.1 mol% Cl$_{2}$ at atmospheric pressure.

physics.optics↗

arXiv2023

Guidance of ultraviolet light down to 190 nm in a hollow-core optical fibre

We report an anti-resonant hollow core fibre with ultraviolet transmission down to 190 nm, covering the entire UV-A, UV-B and much of the UV-C band. Guidance from 190 - 400 nm is achieved apart for a narrow high loss resonance band at 245 - 265 nm. The minimum attenuation is 0.13 dB/m at 235 nm and 0.16 dB/m at 325 nm. With an inscribed core diameter of ~ 12 $\mu$m, the fibre's bend loss at 325 nm was 0.22 dB per turn for a bend radius of 3 cm at 325 nm.

physics.optics↗