Xenon plasma-FIB micromachined cavity-based fiber sensors for refractive index, temperature and chemical sensing

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Xenon plasma-FIB micromachining has been used for relatively rapid (10-20 minutes) production of intrinsic Fabry-Perot cavities in fused silica single and multimode fibers without any post-processing. Infiltration of organic solvents into the cavity produced in the proximity of cleaved-end of a single mode fiber has enabled refractive index sensing with a sensitivity of ∼-65 dB/riu in the range 1.31-1.37. The influence of cavity wall-angle and cleave imperfections on the performance of the sensor have been discussed. Theoretical interpretation shows that the index sensitivity and measurement range can be tailored via the length of the cavity and its distance from the cleaved-end. The same sensor when heated up to 900 °C has shown a wavelength-temperature sensitivity of 8.1 pm/°C and 8.7 pm/°C during the first and second heating cycles respectively owing to the irreversible effects of dopant-diffusion. Multimode fiber cavity has enabled chemical sensing via NIR-absorption spectroscopy of an epoxy resin, amine-based hardener and its affinity for atmospheric moisture, offering scope for remote chemical process monitoring of engineering materials and structures.


Original languageEnglish
Pages (from-to)1736-1756
JournalOSA Continuum
Issue number6
Early online date19 May 2021
Publication statusPublished - 15 Jun 2021