Abstract: An optical sensor for detecting a chemical species in a sample, the optical sensor comprising a single mode fibre having a fibre Bragg grating, wherein the fibre Bragg grating has a refractive index profile, the optical sensor arranged to provide an output optical signal based on a positive detection of the chemical species in the sample, wherein the sample, upon illumination, emits a sample optical signal having an optical frequency signature comprising a plurality of spectral lines that are associated with the chemical species, wherein the refractive index profile is associated with the optical frequency signature, and the fibre Bragg grating is arranged to be modulated to generate the output optical signal.

Abstract: An optical sensor for detecting a chemical species in a sample, the optical sensor comprising a single mode fibre having a fibre Bragg grating, wherein the fibre Bragg grating has a refractive index profile, the optical sensor arranged to provide an output optical signal based on a positive detection of the chemical species in the sample, wherein the sample, upon illumination, emits a sample optical signal having an optical frequency signature comprising a plurality of spectral lines that are associated with the chemical species, wherein the refractive index profile is associated with the optical frequency signature, and the fibre Bragg grating is arranged to be modulated to generate the output optical signal.