From 65438 to 0978, K·O· Hill of the Communication Research Center in Ottawa, Canada, first discovered the photosensitive effect of optical fiber in Germanium-doped quartz fiber, and made the world's first fiber grating by standing wave writing method. 19*, G. Meltz of the United Technology Research Center of the United States and others realized the ultraviolet laser side writing technology of fiber Bragg grating (FBG), and made a breakthrough in the fabrication technology of fiber Bragg grating. With the continuous improvement of fiber grating manufacturing technology, its application results are increasing day by day. Due to the practical application of fiber grating, the whole field from optical fiber communication, optical fiber sensing calculation to optical information processing will undergo revolutionary changes. Fiber Bragg grating (FBG) technology is another major technological breakthrough of fiber technology after erbium-doped fiber amplifier (EDFA) technology.

Fiber grating is made by using the photosensitivity of optical fiber. The so-called photosensitivity in optical fiber refers to the characteristic that the refractive index of optical fiber changes with the spatial distribution of light intensity when laser passes through doped optical fiber. The essence of the spatial phase grating formed in the fiber core is to form a narrow band (transmission or reflection) filter or mirror in the fiber core. Using this characteristic, many unique optical fiber devices can be manufactured, which have a series of excellent properties, such as wide reflection bandwidth, small additional loss, small volume, easy coupling with optical fiber, compatibility with other optical devices, and no influence from environmental dust.

There are many kinds of fiber gratings, which are mainly divided into two types: one is Bragg grating (also known as reflection or short-period grating), and the other is transmission grating (also known as long-period grating). Fiber grating can be divided into periodic structure and aperiodic structure in structure, and can also be divided into filter grating and dispersion compensation grating in function. Among them, the dispersion compensation grating is an aperiodic grating, also called chirp grating. At present, the application of fiber grating is mainly concentrated in the field of optical fiber communication and optical fiber sensor.

In the field of optical fiber sensors, the application prospect of fiber grating sensors is very broad. Because the fiber grating sensor has the advantages of anti-electromagnetic interference, small volume (standard bare fiber is 125um), light weight, good temperature resistance (the upper working temperature can reach 400℃ ~ 600℃), strong multiplexing ability, long transmission distance (the sensor can reach several kilometers to the demodulation end), corrosion resistance, high sensitivity, passive devices, easy deformation and so on, it has been used as early as/. At the same time, fiber grating sensors can also be used in chemical medicine, material industry, water conservancy and electric power, ships, coal mines and other fields, as well as concrete components and structures in the field of civil engineering (such as buildings, bridges, dams, pipelines, tunnels, containers, highways, airport runways and so on). ) to measure the structural integrity and integrity.