Optical fiber sensor is the use of ultraviolet exposure technology in the optical fiber core formed in the periodic distribution of refractive index structure, when a certain bandwidth of light through the ring incident into the optical fiber sensor, because the optical fiber sensor has wavelength selectivity, can only make the specific wavelength of light reflected, and then through the demodulation instrument or spectrometer to measure the wavelength change of reflected light.

The strain and temperature of the measured structure can be measured. The change of period and effective refractive index of optical fiber sensor will affect the reflection spectrum of optical fiber sensor. Any physical process that changes these two parameters will cause the Bouguer wavelength shift.

The sensing process based on optical fiber sensor is caused by the influence of external physical parameters on the period or effective refractive index of optical fiber sensor, which causes the central wavelength of the emitted light to drift.

Compared with traditional electrical sensors, optical fiber sensor sensors have the following advantages:

(1) The sensor probe has simple structure, small size and light weight, and can measure the strain and structural damage of the structure.

(2) There is natural compatibility with optical fiber, no electromagnetic interference, easy to connect with optical fiber, low loss, good spectral characteristics, high reliability.

(3) It is non-conductive, has little impact on the measured medium, and has the characteristics of anti-corrosion and anti-electromagnetic interference, suitable for working in harsh environments.

(4) Light and soft, it can write multiple gratings in one fiber to form a sensing array.

(5) The multiplexing of optical fiber sensors, as a unique technology of optical fiber sensors, can realize the measurement of distributed fields along the optical fiber laying path.