|Principle of fiber Bragg grating|
|Update time：2017-04-13 14:16:00|
Fiber Bragg grating (FBG) is a kind of reflective fiber passive device, which is formed by the change of the refractive index of the doped fiber, and the refractive index of the fiber core is changed by a special process. When the broad band light passes through the fiber grating, the incident light which satisfies the Bragg condition is strongly reflected, and returns along the original transmission fiber. In the past the other transmission wavelength of fiber grating array can continue to transmit to the other with different wavelength, the center wavelength of the corresponding series of narrow-band light will be reflected one by one, all along the transmission fiber return, thereby realizing a plurality of optical fiber grating sensors of WDM, realize quasi distributed measurement. The light is reflected back the centre wavelength of fiber grating with the value of the environment temperature and stress change, and has a good linear relationship, the optical wavelength absolute encoding information of temperature, and the variation of light intensity of the light wave signal is not sensitive, therefore, the optical fiber grating as the temperature sensitive element can be obtained a high precision, and has a good reliability and stability. Based on this, the real-time temperature monitoring system based on Fiber Bragg grating sensing technology is very popular in the field of temperature and strain measurement.