Abstract
We present in this paper a wavelength-encoded fiber-optic temperature sensor with ultra-high sensitivity. The sensor consists of a segment of multimode fiber (MMF) with a polymer cladding spliced between two single mode fibers, forming a multimode fiber interferometer. For a temperature sensor with a 55 mm long MMF and a 45 mm long polymer cladding, a temperature sensitivity of -3.195 nm/degrees C has been achieved over a temperature range of 10 degrees C which is mainly limited by the spectral range of the light source used in the experiments. It has been found that the high temperature sensitivity is mainly attributed to the high thermo-optic coefficient of the polymer cladding. Other advantages of the temperature sensor reported here include its extremely simple structure and fabrication process, and hence a very low cost. (C) 2008 Elsevier B.V. All rights reserved.