Distributed Fiber Optic Sensor For The Detection Of Dynamic Signals Based On Broadband Light Source

Due to the distributed optical fiber sensor’s compact structure with low fares and high-quality, remote measurement, electromagnetic resistance, corrosion resistance, easy to transport the advantages of large capacity, it has been widely attention and research, and has obtained certain achievement in the fields of sensing monitoring.Especially the interferometric sensor based on white light provides a favorable signal absolute measurement of solution, wavelength as the unit of measurement, high sensitivity to the parameter, which is the sensor cannot achieve by coherent light source.But with the rapid development of sensing technology, the demand for detectable signal has from the static, semi dynamic gradually extended to the dynamic and rapidly changing aspects, etc., such as chemical reaction, molecular switch and other transient phenomenon, so fast real-time signal detection is a great challenge. In addition, although interference sensing scheme based on white light has been optimized a lot, such as the development of high performance, high rate of mechanical scanning technology and electronic scanning technology, it is difficult to solve the problem of mutual restriction of scan rate and resolution. So to explore a kind of dynamic interference of signal detection sensor is very meaningful.First, according to the theory of interferometric sensor, this paper builds the interferometric experiments based on Michelson interferometer with ASE source, single wavelength laser common interferometer. However, its performance is severely limited by mechanical scanning components, which is not only at a low scanning speed, but also with poor stability.To improve the interferometric sensor for dynamic rate and stability of the problems of signal detection, this paper presents a kind of scanning method using the dispersion of the fiber, in which the waveform is broadened. The resulting interference occurs when the chirp signal and the original signal match in the coupler. More importantly, the dispersion of the fiber can replace the traditional mechanical scanning device, greatly simplifies the system, so that we can achieve fast and real time testing of the signals. In addition, according to the dispersive scanning, we can demodulate the wavelength of the signal, so it also could be used in wave division multiplexing system and gets the job done with good high testing efficiency, which is of practical value.Finally, by using optisystem, a kind of optical simulation software, this paper proposes a design of scanning system based on the dispersion, discusses and analyzes the four groups of the interference patterns with coherent light source and in-coherent light sources. Then, the results verify the methods proposed in this paper using the dispersive scanning is OK, and proved the correctness and feasibility of the design.