Distributed fiber-optic sensor for location based on polarization-stabilized dual-Mach-Zehnder interferometer

Abstract

A novel distributed fiber-optic sensor is proposed and demonstrated, in which two Mach-Zehnder interferometers are used to detect the interference signals with different wavelengths, and one 3 × 3 coupler is deployed to demodulate the time-varying phase change caused by vibration. The novel dual Mach-Zehnder interferometer (DMZI) is composed of two wavelength division multiplexers. Then, a time delay estimation algorithm is designed to construct two related signals using the phase difference, and the two constructed signals are used to obtain vibration position through cross-correlation. Experimental results show that the sensing distance can reach 100 km and the location error is within ±25 m.

Dual Mach–Zehnder Interferometers With Hierarchical Clustering Analysis Method Applied for Positioning the Intrusion

“…A locating error of 52.5 m was reported for the case of 61-km sensing length, which was much better than that with traditional DMZIs [17]. Faraday rotating mirrors were employed in the work of [18] for eliminating the effect of PIF in the experiment of 100-km sensing distance with a locating error of ±25 m.…”

Ultra-long-range modulated asymmetric vibration sensor based on high-frequency carrier

“…Distributed vibration sensor based on dual Mach-Zehnder interferometer (DMZI) have been successfully applied in many fields such as oil and gas pipeline security monitoring, railroad health monitoring, perimeter security and so on [1,2]. The mainstream method of estimating the time delay between two signals propagating in the forward and reverse directions is usually based on cross-correlation algorithm, whose accuracy is closely related to the bandwidth and similarity of the signals.…”

Distributed Acoustic Sensor Using a Double Sagnac Interferometer Based on Wavelength Division Multiplexing

“…They appear in a spectrum in the presence of an acoustic disturbance due to a time delay between clockwise (CW) and counterclockwise (CWW) radiation. This method can be implemented based on one fiber loop [ 2 ], demonstrated in Figure 1 , or in more complex schemes [ 4 , 5 ] such as the double Sagnac scheme [ 6 ], or another scheme in which a linear section and a Faraday rotator mirror (FRM) form at the output of the imbalanced Mach-Zehnder interferometer (MZI), with a laser coherence length less than the MZI arms’ difference [ 7 , 8 , 9 , 10 ]. In addition, the “null frequency” method was mentioned as an example for comparison in [ 1 , 5 ].…”

“…This method can be implemented based on one fiber loop [ 2 ], demonstrated in Figure 1 , or in more complex schemes [ 4 , 5 ] such as the double Sagnac scheme [ 6 ], or another scheme in which a linear section and a Faraday rotator mirror (FRM) form at the output of the imbalanced Mach-Zehnder interferometer (MZI), with a laser coherence length less than the MZI arms’ difference [ 7 , 8 , 9 , 10 ]. In addition, the “null frequency” method was mentioned as an example for comparison in [ 1 , 5 ]. In [ 8 ], to reduce localization errors, the authors proposed a modified “null frequency” method, which consisted of applying the second Fourier transform to the signal spectrum in order to determine a periodicity of “null frequency” points instead of searching for individual ones.…”

“…It is extremely difficult to determine the position of the low spectral density points or to find out the periodicity of spectrum modulation in the case of high noise. To provide good localization it is necessary to have some prior information about the position of the “null frequency” points, which is possible in a laboratory setup with a stated disturbance position assembled [ 3 ] or if the disturbance position can be obtained as a result of a numerical simulation [ 5 ].…”