Simultaneous temperature and refractive index measurements using a 3/spl deg/ slanted multimode fiber Bragg grating

A novel and simple sensor based on a 3/spl deg/ slanted multimode fiber Bragg grating (MFBG) for simultaneous temperature and refractive index measurement is demonstrated. The 3/spl deg/ slanted MFBG shows two wavelength groups in its transmission spectrum: One group, due to the coupling from one core mode to cladding modes, is sensitive to both surrounding refractive index (SRI) and temperature and the other, due to the coupling from one core mode to other core modes is sensitive only to temperature. Utilizing the obvious difference of two transmission dips in different wavelength groups on the temperature and the refractive index, two parameters can be distinguished and measured simultaneously using one slanted MFBG.