Fiber Bragg Grating Demodulation System Based On Matched Filtering

Fiber Bragg Grating (FBG) has wide application in the fiber sensing, optical fiber communication and other photonics field. Because Fiber Sensing has many advantages, it has become the mainstream direction of the development of sensing technology and developed rapidly in the past 20 years. Reflecting wavelength can be converted to sensing information by FBG, high-precision Optical Spectrum Analyzer (OSA) can be used to achieve reflecting wavelength of precision small displacement detection. However, OSA which in huge size and expensive is difficult for the actual project. So a high precision and low-cost FBG demodulator is one of the key issues for the industrialization of FBG sensor.This paper presents a Bragg demodulation device based on matching fiber grating of transmitting style with the analysis on the literature at home and abroad. A high precision displacement set controlled by the microcontroller was used to move the free end of the cantilever beam to stretch or compress, which implemented the measurement of matched grating and the purpose of temperature or strain signal demodulation. MCU AT89C52 was adopted as the core of under-machine system of the demodulation device, Keil C language was used to program, which completed functions of control high precision displacement set and serial communication. The photoelectric conversion, amplifier and control circuit was design and produced, a multi-channel data acquisition card was used to acquire photoelectric signal. Upper computer programme is written with VC++. The function it achieves are as follows: achieving the running direction, distance, and the subdivision control by serial port; accomplishing data acquisition and real-time rendering of the photoelectric signal acquisition by the curves, as well as the preservation of images and data; realizing the purpose of demodulation of slow sensing signal with the whole scanning method and the method of combining three points.