High-sensitivity temperature sensor based on overlay on side-polished fibers

A temperature sensor based on overlay on side-polished fibers is presented. It works on the basis of the evanescent field coupling between a single-mode side-polished optical fiber and a dielectric waveguide overlay. The spectrum of a white light beam transmitted through the former system exhibit sharp and deep regularly spaced resonances whose central wavelengths are linearly shifted with temperature. It has a wavelength sensitivity of similar to 1 nm/degrees C, which is one order of magnitude better than that obtained with fiber Bragg sensors.