Magnetic field sensor and measurement method based on fiber Bragg grating laser

Abstract

The invention discloses a magnetic field sensor and a measurement method based on a fiber Bragg grating laser. The magnetic field sensor comprises the fiber Bragg grating laser, a polarizer and a photoelectric detector, which are sequentially connected, wherein linear birefringence which is generated in the laser cavity of the fiber Bragg grating laser is combined with circular birefringence caused by a magnetic field to be measured to form elliptical birefringence; the fiber Bragg grating laser works in a single-longitudinal-mode double-cross-polarization state to generate two laser outputs which belong to a longitudinal mode, have frequency difference and are crossed in a polarization state; the two laser outputs pass through the polarizer, and are input into the photoelectric detector and then mixed to generate a beat frequency signal; and by detecting the frequency change of the beat frequency signal, the change of the elliptical birefringence is calculated, and then the magnetic field intensity of the magnetic field to be measured is computed. The invention has the characteristics of small size and flexibility, and is particularly applicable to an application occasion where the point measurement is required. The problems that the conventional magnetic field sensor is large in size and difficult to apply to the application occasion where the point measurement is required are solved.

Description

technical field [0001] The invention relates to fiber optical measurement of magnetic field, in particular to a magnetic field sensor and a measurement method based on a fiber grating laser. Background technique [0002] Fiber Bragg Grating is made by using the photosensitivity of doped fiber, and the refractive index of the fiber is permanently changed by special light irradiation. The fiber grating can reflect the incident light that satisfies the Bragg reflection condition, which is equivalent to directly writing a wavelength-selective reflector inside the optical fiber. Sensors made of fiber gratings have the advantages of small size, light weight, and high signal-to-noise ratio. However, most of these sensors use wavelength shift detection, which is complex and expensive, and the detection resolution and dynamic range are limited by the detection device. [0003] In terms of optical fiber optic measurement of magnetic field, it can be divided into direct measurement a...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a magnetic field sensor based on a fiber grating laser. The designed sensor is small and flexible, and is especially suitable for applications that require point measurement. It solves the problem that the existing magnetic field sensors are large in size and difficult to apply to applications that require point measurement The problem

[0006] Another object of the present invention is to provide a magnetic field measurement method based on a fiber grating laser, aiming to solve the problem that the existing magnetic field measurement method is difficult to apply to point measurement occasions

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