1. Introduction . Since the mass production of FBG, it has become a research hotspot in the field of communication and sensing [ 1 ]. As a new type of optical fiber sensor, FBG has the characteristics of light weight, small size, high sensitivity, corrosion resistance, electromagnetic interference resistance and easy networking compared with traditional sensors, and is widely used in the safety monitoring of aerospace, petrochemical, civil engineering, etc. [ 2 ]. As a wavelength modula...