Optical fiber grating microbend sensor based on cladding mode transmission

Abstract

The invention provides an optical fiber grating microbend sensor based on cladding mode transmission, belonging to the technical field of optical fiber sensing. The microbend sensor is characterized by consisting of a long-cycle optical fiber grating (1), a Prague optical fiber grating (2), a monomode optical fiber (3), an encapsulation sleeve (4) and a connector (5); light is transmitted in the monomode optical fiber (3), when the light passes through the long-cycle optical fiber grating (1), part fiber core modes are coupled in the cladding layer of the long-cycle optical fiber grating (1), the cladding mode and the surplus fiber core modes are transmitted along the monomode optical fiber (3), and pass through the optical fiber grating (2), light which meets two different wavelengths of the Bragg condition is reflected, and two peaks which are respectively corresponding to the cladding mode and the fiber core modes occur in the reflection spectrum; when the long-cycle optical fiber grating (1) bends, the bending degree of the long-cycle optical fiber grating (1) is measured through measuring the deviation of two peaks; and the sensor has high sensitivity, high external electromagnetic disturbance resistant capability, and can be applied to each type of practical engineering.

Description

technical field [0001] The invention provides a fiber grating microbending sensor based on cladding mode transmission, which belongs to the technical field of fiber optic sensing. Background technique [0002] Based on many advantages such as simple structure, anti-electromagnetic interference, and suitable for long-distance and distributed sensing, fiber optic sensors have been widely used and researched in practical engineering. A lot of research has been done on microbending sensors based on long-period fiber gratings. Long-period fiber gratings couple the core mode into the cladding, and bending long-period fiber gratings can affect the coupling efficiency from the core mode to the cladding mode, thereby Implement bend sensing. Usually, the previously proposed microbend sensors based on long-period fiber grating structures are often affected by other parameters, such as temperature and stress, when performing bending measurements. Moreover, the mode coupling of LPFG oc...

AI Technical Summary

Problems solved by technology

Then, the core mode where the tilted fiber grating is coupled into the cladding has a very wide wavelength band, thus increasing the difficulty in multiplexing and wavelength demodulation

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