We present the measurement of the temperature variation along a fiber Bragg grating (FBG) written in a photosensitive fiber, using azimuthal whispering gallery modes (WGM) resonances of the fiber itself. The FBG is regarded as a cylindrical microresonator, in which the azimuthal WGM resonances are excited with an auxiliary 2 μm taper. The wavelengths of the WGM resonances shift as the temperature of the grating increases at a given point. The temperature profile along the FBG is obtained by monitoring the WGM resonances at different points, as a function of the power and wavelength of the optical signal. Our experiments give useful information to study the small absorption changes produces by the standard UV photo-inscription technique and the thermally induced chirping effects generated when FBGs are used with moderate power levels.

Date Published: 2 June 2014
PDF: 4 pages
Proc. SPIE 9157, 23rd International Conference on Optical Fibre Sensors, 91578B (2 June 2014); doi: 10.1117/12.2059559

Published in SPIE Proceedings Vol. 9157:
23rd International Conference on Optical Fibre Sensors
José M. López-Higuera; Julian D. C. Jones; Manuel López-Amo; José Luis Santos, Editor(s)