Research On Signal Demodulation And Remote Monitoring Of Reflected Bragg Wavelength

Fiber Bragg grating sensors can make up the optical fiber sensing network to take multi parameter and multiple point monitoring for the large-scale and complex structure environment through WDM, SDM, TDM and other various multiplexing technology, etc. However, if the number of monitoring object and fiber Bragg grating sensors increase, the key of the whole sensing system is how to accurate addressing the sensing FBG and demodulating the center wavelength of sensing FBG. Meanwhile with the development of Internet technology, combined fiber optical Bragg grating sensing technology and the Internet technology can realize remote monitoring. In this article, by using the demodulation technology of imaging spectrometry to design the quasi distributed demodulation system of fiber Bragg grating, at the same time develop the fiber grating remote monitoring system based on B/S mode, that could realize the remote access to the signal was collected by fiber Bragg grating demodulation system. The main content of this paper is as follows:(1) The demodulation technology of imaging spectrometry based on the Volume Phase Holographic Grating and the InGaAs array detector, which is combined the SDM and WDM to design the quasi distributed demodulation system of fiber Bragg grating with 16 channels. This paper has done the detailed design the structure of this demodulation system. Through choosing the demodulation module, broadband light source, optical switch module and related devices. And also analysis these optical device interface, design the hardware circuit of the demodulation system(the hardware circuit included the power conversion module, optical switch control module, communication module). Finally, the demodulation system is realized by building, this system can realize the multiport communicating with PC between RS-232 and USB.(2) PC software of demodulation system was developed by using Microsoft Visual Studio 2008 and Measurement Studio software. At the same time, multithreading technology was used. The PC software has the function of collecting data of demodulation module, controlling of optical switch, describing and displaying of data, storing the data.(3) Development of a fiber grating remote monitoring system was based on B/S mode, also the data communication of this system was designed. By accessing the Web network and using Java Database Connectivity (JDBC) to establish a connection with the database of remote monitoring system which is on the Web server. The detection data of different channels and different fiber Bragg grating sensors was displayed in the browser interface, which was collected by fiber Bragg grating demodulation system. And realized the remote monitoring of different monitoring objects and monitoring points. By querying the sequence diagram of the remote monitoring system, the state of a monitoring object for a specified period of time can be analyzed.