Magnetic fluid filled MNF and FBG cascaded stress and magnetic field sensing device

Abstract

The invention provides a magnetofluid filled MNF and FBG cascaded temperature and magnetic field sensing device. The magnetofluid filled MNF and FBG cascaded temperature and magnetic field sensing device comprises an ASE light source (1), a circulator (2), a double-parameter measurement sensing device (3), a spectrometer (4), a demodulator (5) and a computer processor (6). According to the invention, a Mach-Zehnder interferometer principle and an FBG sensing principle are adopted, sensing is carried out by cascading a Mach-Zehnder structure of a magnetic fluid material packaged by a SiO2 nanotube with an FBG, a light beam generated by an ASE light source generates an interference spectrum in a Mach-Zehnder interference structure, measurement of a magnetic field is realized through detection of the interference spectrum, and the magnetic field is measured through a reflection peak generated by the FBG. The temperature change is detected, demodulated through the demodulator and processed on the computer processor, and the purpose of digitization is achieved. The stress and the magnetic field are measured at the same time, cross sensitivity is avoided, the size of the sensor is reduced, the stress and the magnetic field can be output on a computer processor, and the purpose of monitoring the stress and the magnetic field at the same time in real time is achieved.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing, and in particular relates to a stress and magnetic field sensing device cascaded with magnetic fluid filled MNF and FBG. Background technique [0002] Compared with traditional electronic sensors, optical fiber sensors have high signal-to-noise ratio, remote monitoring, no electromagnetic interference, high sensitivity, and high flexibility. Nowadays, many sensors that can measure temperature, stress, and pressure have been developed. and other fiber optic sensors. In recent years, with the continuous development of science and technology and economy, the demand for intelligence has continued to increase, and the demand for multi-functional and small sensors has gradually expanded, which has broad application prospects in the fields of biology, chemistry and medicine. Therefore, the development of multi-parameter measuring sensors has become an inevitable trend. Designing a compos...

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Problems solved by technology

For example: in 2014, Yao Q et al. (Yao Q, Meng H, Wang W, et al.Simultaneous measurement of refractive index and temperature based on a core-offset Mach–Zehnder interferometer combined with a fiber Bragg grating[J].Sensors and Actuators A: Physical, 2014, 209: 73-77.) An all-fiber sensor for simultaneously measuring the refractive index and temperature of the solution is proposed. This structure uses a single-mode optical fiber dislocation cascade to form a Mach-Zehnder interferometer cascaded with a FBG structure for dual-parameter measurement, but the bending of the sensing head of the sensor affects the stability of the device; in 2015, Li C et al. (Li C, Ning T, Wen X, et al. Magnetic field and temperature sensor based on a no-core fiber combined with a fiber Bragggrating[J]. Optics&Laser Technology, 2015,72:104-107.) proposed an optical sensing device for dual-parameter measurement of magnetic field and temperature, using a sensor device composed of a coreless optical fiber and a fiber Bragg grating cascaded, although It can measure the dual parameters of magnetic field and temperature, but the structure is simple and the interference effect is not obvious, resulting in poor sensor performance, low sensitivity, and small measurement range; in 2018, Chen F et al. (Chen F, Jiang Y, Zhang L, et al. Fiber optic refractive index and magnetic field sensors based on microhole-induced inline Mach–Zehnder interferometers[J].Measurement Science and Technology,2018,29(4):045103. The acid (HF) corrosion method corrodes the end face of the single-mode fiber and cascades the single-mode fiber to realize the online MZI structure, immersing it in the magnetic fluid to realize the magnetic field sensing, and immersing the MZI structure into liquids of different concentrations to realize Refractive index measurement. Although the sensing unit can realize dual-parameter detection, it cannot detect at the same time; in 2020, Tong R et al. (Gao S, Ji C, Ning Q, et al. High-sensitiv e Mach-Zehnder interferometric temperature fiber-optic sensor based on core-offset splicing technique[J].Optical Fiber Technology,2020,56:102202.) Mach-Zehnder interference is made by connecting the two ends of the optical fiber with misalignment and filling the refractive index matching liquid Although the sensitivity of the sensor is improved compared to filling, the performance is poor due to the large optical loss due to the dislocation at both ends; in 2020, Xia F et al. (Xia F, Zhao Y, Zheng H, et al. Ultra-sensitive seawater temperature sensor using an FBG-cascaded microfiber MZI operating at dispersion turning point[J]. Optics&Laser Technology, 2020, 132:106458.) proposes an optical fiber sensor for seawater temperature detection, which uses an FBG and micro-nano fiber cascaded structure to achieve temperature detection, wherein The surface of the micro-nano fiber is coated with PDMS temperature-sensitive material to produce MZI, and the cascaded structure enhances the sensitivity and detection range. Although the sensing unit achieves a wide detection range of temperature, the structure is complex and only a single parameter can be measured; 2021 , Sun Dandan et al. (Sun Dandan, Yang Run. Interferometric micro-nano optical fiber temperature sensor based on nanomaterial packaging [J]. Acta Quantum Optics, 2021, 27(03):227-234.) proposed an interferometric sensor based on nanomaterial packaging Micro-nano optical fiber temperature sensor, but it cannot perform multi-parameter measurement and cannot meet the needs of the real environment, and the filling liquid will reduce the sensitivity of the sensor

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