Simultaneous Measurement of Strain and Temperature by Using a Micro-Tapered Fiber Grating

We investigate a periodically micro-tapered fiber grating for simultaneous measurement of strain and temperature. The fundamental core mode can be coupled to the cladding mode by tapering a single-mode fiber periodically, which results to the resonant wavelength. The coupling strength is directly proportional to the number of micro-tapered regions in the cladding. The transmission characteristics of the periodically micro-tapered fiber grating are measured as strain or temperature is changed. The resonant wavelength is shifted to shorter wavelengths and the transmission is reduced as the applied strain increases. However, as the applied temperature increases, the resonant wavelength is shifted to longer wavelengths and the transmission is also diminished. Consequently, it is possible to effectively discriminate concurrent sensitivities between strain and temperature by measuring the resonant wavelength shift and the transmission variation of the periodically micro-tapered fiber grating.