基于模间干涉原理,将单模-多模-单模(SMS)光纤结构运用于光纤安防系统中。以多模光纤为传感光纤,结合小波变换处理,实现对外界振动入侵事件的探测。理论分析了多模光纤的模间干涉原理,并分别将两路传感光纤置于围栏和铺设在地面上,对几种振动入侵事件进行实验分析。研究结果表明:该结构型传感器能够快速有效地探测到振动入侵信号,在光纤安防领域中具有较好的可行性。该结构型传感系统由于其结构简单、成本低廉等优点,在光纤安防系统中具有重要意义。

Based on the principle of inter mode interference, we apply the single mode-multimode-single mode (SMS) optical fiber structure to the optical fiber security system. In the system, multimode optical fiber is used as sensing fiber, and wavelet transform is used to realize the detection of external vibration signals. The theory of intermodal interference of multimode optical fiber is analyzed. The sensing optical fiber is arranged in the fence and laid on the ground, respectively. Several vibration invasive events are analyzed in experiment. The experimental results show that the sensing system of this structure can detect the vibration invasive signal quickly and effectively, and it has good feasibility in the field of security in optical fiber. The structure sensing system maintains the advantages of simple structure, low-cost, which has very important significance in optical fiber security systems.