Refractive‐index sensor based on tilted fiber Bragg grating interacting with multimode fiber

Abstract A simple refractive‐index fiber sensor based on a tilted Bragg fiber grating (TFBG) interacting with multimode fiber (MMF) is described. The sensor structure is formed by insertion of a small section of MMF between the single‐mode fiber and the TFBG. The average reflective power in the cladding modes of the TFBG reflected a different power as the surrounding refractive index changes, while the power of the reflected Bragg mode keeps unchanged. Therefore, the power of the reflected Bragg mode can be used as a reference to compensate any possible fluctuation of the light source power. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 1375–1377, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25178