High-sensitivity all-fiber current measuring device and method with dual-cycle structure

Abstract

The invention discloses a high-sensitivity all-fiber current measuring device and method with a dual-cycle structure. The device comprises a broadband light source, a polarizer, a polarization controller, a first polarization beam splitter, a first coupler, a circulator, a second coupler, a sensing optical fiber ring, a current-carrying conductor, a first Faraday rotator mirror, a second Faraday rotator mirror, a second polarization beam splitter, a first photoelectric detector and a second photoelectric detector. According to the sensor, the polarization beam splitter, the first coupler, thedouble Faraday rotating mirror and the second coupler are combined to form a double-circulation structure, so that optical signals are circulated for multiple times in a sensing optical path, the sensitivity of the sensor is improved while the stability of a system is enhanced, and the influence of a linear birefringence effect is reduced.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a high-sensitivity all-fiber current measuring device and method with a double loop structure. Background technique [0002] Because the fiber optic current sensor has the advantages of good insulation performance, strong anti-electromagnetic interference, simple structure, and safety, it is very suitable for current applications. [0003] The working principle of the fiber optic current sensor is based on the Faraday magneto-optical effect, that is, the current to be measured forms a Faraday phase shift in the sensor that is linearly related to it. The current mainstream solutions all construct interference optical paths, use phase modulators and introduce closed-loop control algorithms. The Faraday phase shift is demodulated according to the interference light intensity signal, and the current to be measured is obtained from the demodulation result. S...

AI Technical Summary

Problems solved by technology

Since the demodulation of the Faraday phase shift depends on the interference light intensity signal, and the interference light intensity is affected by the power of the light source, how to eliminate the influence of light source power fluctuations is one of the problems that the existing schemes must face; the interference light intensity and the Faraday phase shift It is a cosine function relationship, which is a nonlinear function relationship. In addition, the Faraday phase shift is a weak signal. In this case, the first derivative value of the cosine function is close to 0. How to improve the measurement sensitivity of the sensor and solve the nonlinear problem It is the second problem that the existing scheme must face directly; the modulation and demodulation of Faraday phase shift is realized by the phase modulator, the modulation period is related to the transit time of the sensor, and the transit time depends on the length of the polarization maintaining delay fiber ring, the sensor Therefore, the bandwidth is limited. The highest known bandwidth is about 100kHz. The polarization maintaining optical fiber ring also increases the cost of the sensor. This is the third problem that the existing scheme must face; the high price of the phase modulator directly increases the The cost of using sensors is also the fourth problem that existing solutions must face

At present, some of these problems have been solved by complex control algorithms, but some belong to the inherent problems of the sensing scheme, which are difficult to overcome

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