Multiple optical fiber sensing with a single data channel of optical frequency-domain reflectometry

Fully distributed strain sensing of multiple optical fibers normally requires assigning each fiber a dedicated data channel. However, in this Letter, we show that using a single data channel of optical frequency-domain reflectometry, simultaneous measurement along multiple fibers combined with optical couplers can be realized by taking the advantage that each fiber has its unique Rayleigh backscattering pattern which can be used as a key signature for identifying sensing information, even though the individual pattern is buried in the signals contributed from all the fibers. Preliminary results show that four single-mode fibers, with the feasibility to be extended to six, can be demodulated simultaneously with spatial resolutions of the order of millimeter, offering great system simplicity and cost reduction for fully distributed strain sensing of multiple optical fibers or multiple cores in a specialty fiber.