Microstructured optical fiber sensor

A microstructured optical fiber sensor operable up to a predetermined temperature for sensing changes in a physical characteristic, comprising:

• a microstructured optical fiber comprising:
• an inner suspended core;
• an outer jacket region;
• at least three longitudinal channels extending along the microstructured optical fiber;
• intra-channel struts separating the at least three longitudinal channels and extending radially from the inner suspended core to the outer jacket region;
• a fiber Bragg grating formed in the microstructured optical fiber by generating a periodic modulation in the refractive index along a core region of the suspended core, the fiber Bragg grating configured to produce a band reflection spectra comprising a fundamental mode and a plurality of higher order modes whose respective wavelengths vary in accordance with changes in the physical characteristic at the core region of the microstructured optical fiber, wherein the microstructured optical fiber is configured in operation to increase a confinement loss of the plurality of higher order modes of the band reflection spectra relative to the fundamental mode,
• wherein the microstructured optical fiber sensor includes an interrogation end for measurement of the band reflection spectra and an operating length corresponding to the distance between a sensing location comprising the fiber Bragg grating and the interrogation end,
• wherein the microstructured optical fiber sensor is configured to have a predetermined confinement loss of the plurality of higher order modes relative to the fundamental mode based on the operating length, and
• wherein the predetermined confinement loss of the plurality of higher order modes of the band reflection spectra relative to the fundamental mode is selected to suppress the plurality of higher order modes to allow measurement only of the fundamental mode at the interrogation end.