Large-scale multiplexing of interferometric fiber-optic sensors using TDM and DWDM

This paper describes multiplexing schemes for interferometric fiber sensors based on time-division multiplexed and dense wavelength-division multiplexing using optical add/drop multiplexers, The results of an experimental arrangement, which is based on one of the architectures, is also presented. Topics include a discussion of the noise sources in the system, dynamic range, and a characterization of the distributed feedback fiber laser source noise. We show the crosstalk levels in the experimental arrangement to be between -47 and -76 dB depending on the mechanism involved. The multiplexing schemes demonstrate the potential to address at least 192 interferometric sensors through two fibers based on a system with six wavelengths with a phase resolution less than 20 mu rad/root Hz. For application to sonar arrays, our analysis has shown that hydrophones multiplexed in this type of architecture would achieve ambient acoustic noise-limited pressure resolution with an in-water dynamic range up to 135 dB at frequencies up to 10 kHz, In general, these architectures would find application in systems requiring very large numbers of sensors with a minimum of telemetry cabling required.