Fiber grating sensor belongs to a kind of fiber sensor. The sensing process based on fiber grating is to obtain sensing information by modulating the Bragg wavelength of external physical parameters. It is a kind of wavelength modulated fiber sensor.

The principle structure of fiber grating sensor is shown in the figure, including: a wide spectrum light source (such as sled or ASE) will have a certain bandwidth of light through the circulator into the fiber grating, due to the wavelength selectivity of the fiber grating, the qualified light is reflected back, and then sent to the demodulation device through the circulator to measure the reflected wavelength change of the fiber grating. When the FBG is used as a probe to measure the temperature, pressure or stress of the outside world, the grating spacing changes, which causes the change of the reflection wavelength. The demodulation device deduces the temperature or strain of the outside world by detecting the change of the wavelength.

Advantages of fiber Bragg grating sensor:

(1) Anti electromagnetic interference: generally, the frequency of electromagnetic radiation is much lower than that of light wave, so the optical signal transmitted in optical fiber is not affected by electromagnetic interference.

(2) Electrical insulation performance is good, safe and reliable: optical fiber itself is composed of dielectric, and does not need power drive, so it is suitable for use in flammable and explosive oil, gas, chemical production.

(3) Corrosion resistance, chemical stability: as the material of optical fiber quartz has high chemical stability, optical fiber sensor is suitable for use in harsh environment.

(4) Small size, light weight, plastic geometry.

(5) Small transmission loss: remote monitoring can be realized.

(6) Large transmission capacity: multi point distributed measurement can be realized.

(7) Wide measuring range: it can measure temperature, pressure, strain, stress, liquid level, displacement, acceleration, etc.

Fiber Bragg grating sensor is widely used in long-term monitoring with its own advantages. At present, the development of optical fiber sensor technology is becoming more and more mature, with a wide range of applications. Many applications in various fields show a booming trend, which is very likely to replace the traditional sensor. In the aspect of fiber sensing, fiber Bragg grating technology has opened up a new field for the development of fiber sensing technology. Fiber Bragg grating sensor has light weight, small volume, high sensitivity, corrosion resistance, anti electromagnetic interference, and good long-term stability and durability. Because of the above advantages, fiber Bragg grating sensor has broad application prospects and practical significance in long-term monitoring projects.

Editor in charge: CC

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