A novel all-fibre cavity ring down spectroscopy technique is proposed where a tilt fibre Bragg grating (TFBG) or long-period grating (LPG) in the cavity provides sensitivity to surrounding medium. Such configuration with an LPG as the representative was theoretically analyzed. Two spectral bands were identified employable for sensing of surrounding refractive index for a weak LPG while only one band existed for a strong LPG. A TFBG, with enhanced sensitivity compared to usual LPGs, was used in a ring down cavity of 1 m constructed with 2 fibre Bragg gratings as the reflectors and the decay time changed from 220 to 450 ns when the TFBG was immersed into water from air.
Bibliographical noteNOTICE: this is the author’s version of a work that was accepted for publication in Optics and Lasers in Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Zhou, Kaiming; Webb, David J.; Farries, Mark; Hayes, Neil; Zhang, Lin and Bennion, Ian (2009). Biochemical sensor based on a novel all-fibre cavity ring down spectroscopy technique incorporating a tilted fibre Bragg grating. Optics and Lasers in Engineering, 47 (10), pp. 1023-1027. DOI 10.1016/j.optlaseng.2009.04.001
- cavity ring down
- long-period grating
- tilted fibre Bragg grating
- optical fibre sensor