Sampled fiber Bragg grating for simultaneous refractive-index and temperature measurement

We present a novel scheme for simultaneous measurement of temperature and refractive index by use of a single sampled fiber Bragg grating (SFBG). The intrinsic nature of a SFBG that possesses both fiber Bragg grating and long-period grating spectral responses permits the temperature effect to the measured solely from the former, whereas the refractive-index information is extracted from the latter. Using such a dual-parameter sensor, we successfully demonstrated measurement of the dependence on temperature of the refractive index of an aqueous solution of sucrose.