Optical fiber sensor, preparation method thereof, detection system and detection method

The invention relates to an optical fiber sensor, a preparation method thereof, a detection system and a detection method. The optical fiber sensor includes: an optical fiber core; a first coating layer which coats the periphery of the optical fiber core; a second coating layer which coats the periphery of the first coating layer, wherein the second coating layer can react with an element to be detected to generate a reaction product, and the interface refractive index of the second coating layer and the first coating layer changes along with the change of the generation amount of the reaction product and/or the change of the type of the reaction product. The interface refractive index directly affects the peak energy intensity of the reflection spectrum of the optical fiber sensor, so that the rapid measurement and calibration of different types or different element concentrations are realized by comparing the difference of the peak intensity of the reflection spectrum of the optical fiber sensor and the pea