Quasidistributed fiber Bragg grating sensor network based on self-heterodyne detection technique

A serial time-division multiplexing optical fiber sensing network with a large multiplexing capacity, which is based on identical ultraweak fiber Bragg gratings (FBGs) and self-heterodyne detection technique, is proposed. An experimental system, which has 10 identical ultraweak FBGs with the same Bragg wavelength of 1550 nm, reflectivity of -36 dB, and bandwidth of 0.1 nm, is set up to investigate the performance of the proposed scheme. The spectra of 10 ultraweak FBGs are resolved with a high accuracy, and the wavelength-temperature sensitivity and temperature resolution of the system are 10.5 pm/degrees C, 0.09 degrees C, respectively. A self-heterodyne detection technique is adopted to increase the sensitivity of the receiver, which makes it possible to multiplex over 1000 FBGs along a single optical fiber. Theoretical analyses demonstrate that this sensing scheme can effectively increase the multiplexing capacity and measurement accuracy. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)