Ultrasensitive plasmonic sensing in air using optical fibre spectral combs.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 27834366.
- Also identified by DOI 10.1038/ncomms13371 and PMC identifier 5114639.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Surface plasmon polaritons (SPP) can be excited on metal-coated optical fibres, enabling the accurate monitoring of refractive index changes. Configurations reported so far mainly operate in liquids but not in air because of a mismatch between permittivities of guided light modes and the surrounding medium. Here we demonstrate a plasmonic optical fibre platform that overcomes this limitation. The underpinning of our work is a grating architecture-a gold-coated highly tilted Bragg grating-that excites a spectral comb of narrowband-cladding modes with effective indices near 1.0 and below. Using conventional spectral interrogation, we measure shifts of the SPP-matched resonances in response to static atmospheric pressure changes. A dynamic experiment conducted using a laser lined-up with an SPP-matched resonance demonstrates the ability to detect an acoustic wave with a resolution of 10<sup>-8</sup> refractive index unit (RIU). We believe that this configuration opens research directions for highly sensitive plasmonic sensing in gas.