Optical time-domain reflectometry interrogation of multiplexing low-reflectance Bragg-grating-based sensor system

Low-reflectance fiber Bragg gratings (FBGs) can be interrogated in real time with a high-resolution optical time-domain reflectometry (OTDR) technology. The technique allows interrogation of a series of FBGs with the intensity change based on the OTDR pulse spectral characteristics and the FBG reflection. Experimental results are presented for multiplexing of dual-wavelength FBG sensors to produce referencing calibration in sensor measurement. With this structure, the influence of the source power fluctuations and fiber bend losses can be greatly reduced. This scheme can be applied to the practical measurement of distributed temperature or strain. (C) 2003 society of Photo-optical Instrumentation Engineers.