The Study Of New Demodulating Technology Of FBG Sensor

Signal demodulating technology of Fiber Bragg Grating (FBG) sensing system is one of critical factors which limit the development of FBG sensing technology. In this paper, progress of FBG sensing system demodulating technology in recent years was reviewed, problems exist in this field were analyzed, according to actual requirement of FBG sensing system, existing signal demodulating technology of FBG sensing system were classified combined with FBG sensing technology, on the basis of this, demodulating technology using amplified spontaneous emission (ASE) light source linear sidebands and it's operational principle were introduced, temperature and strain sensing experiments were made based on the technology. Demodulating schemes which apply Allayed Waveguide Grating (AWG) to FBG sensing system and use Coarse Wavelength Division Mutiplexing (CWDM) linear sidebands filter to demodulate FBG sensing system signals were put forward on the basis of aggregate analysis of advantages and disadvantages of existing demodulating technology.Owing to powerful multiplexing/demultiplexing ability, AWG has great superiorities in the field of FBG sensing technology. In this paper, structure and operational principle of AWG was elaborated. Distributed FBG temperature alarming system based on AWG demodulating was set up in order to use AWG to realize FBG signal demodulation, and it's was realized by VC++ program simulation.Due to so many advantages such as high sensitivity, low cost, the ability to realize static and dynamic sensing, use CWDM linear sidebands filtering to demodulate FBG sensing system signals has a good applying future. In this paper, operational principle of CWDM linear sidebands filtering demodulation was elaborated and, experimental verification was made. Experiments were divided into static sensing experiments and dynamic sensing experiments. Use amplified spontaneous emission light source combined with CWDM linear sidebands demodulation to demodulated strain signals which generated by changing magnetic field acted on Giant Magnetostrictive Material (GMM) consequently acted on FBG refer to characteristics of magnetostrictive material. In static sensing experiments, direct current signals were input in GMM strain model, and alternate current signals in dynamic sensing experiment. Finally, experiment data was processed by MATLAB and sensitivities were calculated, and feasibility of this scheme was demonstrated.Meaningful, fundamental and experimental research has been done on AWG demodulating technology and CWDM linear sidebands demodulating technology in this paper, a new and valuable reference was offered to demodulating technology of Fiber Bragg Grating sensor.