Improved localization algorithm for distributed fiber-optic sensor based on merged Michelson-Sagnac interferometer

Abstract

A novel distributed fiber-optic localization algorithm with high sensitivity and precision based on merged Michelson-Sagnac interferometer is proposed and demonstrated. By performing simple addition and subtraction processing on the two phase differences of the two interferometers, two superimposed signals with a fixed delay can be obtained. The time delay can be calculated by a cross-correlation algorithm. Combined with the polynomial fitting interpolation, the disturbance location resolution is significantly improved. The total sensing distance can reach 120 km, and the localization errors are within ±35 m and ±160 m in the contact and non-contact disturbance experiment, respectively.

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

“…However, the delay time varies due to detection noises and nuisances, as revealed in [19,Figs. 6,7,[9][10][11][12][13][14]. This situation can be seen again from an example taken by heavily tapping the fiber cable for simulating an intrusion at the position of L − d = 1 m. The position of disturbance corresponds to a position number of 0.02.…”

“…Michelson interferometers were also used for distributed disturbance detection [8], [9]. Systems that combined different types of interferometers were also studied for detecting and locating the disturbance applied on sensing fibers, such as those with merged Sagnac and Michelson interferometers [10], [11] and those with combined Sagnac and Mach-Zehnder interferometers [12], [13].…”

Unidirectional Ultra-Long Distributed Optical Fiber Sensor

“…Distributed vibration sensing (DVS) using optical fibers has been widely applied in many engineering areas including structural health monitoring, oil or gas pipeline leakage monitoring, perimeter protection and seismic sensing applications [1][2][3][4][5]. Among them, because of the advantages of high sensitivity, fast response and simple structure, distributed interferometer sensors, including Mach-Zehnder interferometer (MZI) [6], Michelson interferometer [7], Sagnac interferometer [8] and hybrid interferometer structures [9][10], have attracted much research attention and have been extensively studied over the past decades. In interferometer-based DVS systems, light beams are bidirectionally transmitted in a single fiber.…”

A self‐tracking phase retrieval algorithm used in distributed disturbance sensing

“…9,10 In conventional processed method, due to the relatively robustness of state of sensing path, the direct part of interference light is processed as a time-delayed slow variable, therefore, the DC compensation value is set up unchanged in the following sensing period. [11][12][13][14][15] However, in some situations, when sudden changes are introduced in the sensing path, the direct part of interference light cannot be regarded as a timedelayed slow variable for it will bring a remarkable deviation to the retrieval result.…”

“…During the retrieval process, the direct part of interference light, which reflects the static state of the sensing structure, should be compensated in the first place as it is filtered out with asymmetric direct light by the circuit filter 9,10 . In conventional processed method, due to the relatively robustness of state of sensing path, the direct part of interference light is processed as a time‐delayed slow variable, therefore, the DC compensation value is set up unchanged in the following sensing period 11‐15 . However, in some situations, when sudden changes are introduced in the sensing path, the direct part of interference light cannot be regarded as a time‐delayed slow variable for it will bring a remarkable deviation to the retrieval result.…”