1671-7694/2015/010401(4) 010401-1 © 2015 Chinese Optics Letters Optical fiber acoustic sensing multiplexing system based on TDM/SFDM

We propose a system of time-division multiplexing (TDM) and spatial frequency-division multiplexing (SFDM). Extrinsic Fabry–Perot interferometric sensors are applied to detect weak acoustic signals. The broadband source is employed, the light from it is modulated by a pulse signal sequence and is efficiently amplified by semiconductor optical amplifiers. Experimental results show that the equivalent noise pressure spectrum level is −97.2 dB re 1 rad/√Hz below 1250 Hz, and the cross talk between two sensors in one TDM channel is −32.7 dB with a cavity length difference of 60 μm. The number of sensors in this multiplexing system can theoretically reach 160