Acoustic fiber sensor arrays

Abstract

The acoustic fiber sensor arrays that have been developed over the past two decades for oil exploration and other applications can support hundreds of fiber hydrophones per fiber pair and exhibit exceptional properties, including shot-noiselimited sensitivities better than 1 tradt\JHz, high stability, and dynamic ranges well in excess of 130 dB. This article reviews the main configurations reported to date, which are based on ladder architectures utilizing either Mach-Zehnder or Sagnac interferometric sensors and time-domain multiplexing. The emphasis is placed on their principles, performance characteristics, and relative advantages regarding such key issues as signal fading, polarization-induced fading, frequency response, sensitivity, and the number of sensors that can be multiplexed on a given pair of fibers.

Fiber‐optic sensor active networking with distributed erbium‐doped fiber and Raman amplification

“…One of the most straightforward applications of optical amplifiers in sensor networking would be their use as loss-compensating devices in the form of either inline amplifiers, preamplifiers (before the detector), or power amplifiers (immediately after the light source). The use of optical amplification in the distribution topology has been theoretically proposed to increase the number of sensors up to some hundreds, while maintaining fairly good signal-to-noise ratios for all the sensors in the structure [2,10,26,36].…”

“…Such limits were initially observed in [7]. From this point of view, distributed amplification is preferred to lumped amplification for this kind of network, as stated in [2].…”

“…The signal-to-noise ratio and sensitivity of the photodetector will limit the number of the sensors multiplexed into the network. Several studies [2,3,[25][26][27][28] have explored these limits. Sect.…”

“…Experimental results have demonstrated up to 96 sensors multiplexed in a single system, although theoretically more than 300 sensors can be multiplexed using a doublebus configuration [2]. The signal-to-noise ratio and sensitivity of the photodetector will limit the number of the sensors multiplexed into the network.…”

“…Sensor multiplexing networks have to deal with the problem of power losses due to the distribution architecture. In this context optical amplification is a possible solution for the problem of poor power budgets, compensating for splitting losses and greatly increasing the number of sensors per fiber on the network [1][2][3].…”