Research And Application On Fiber Optic Interferometer Loop

The rapid development of optical communication technology makes the fiber-optic cables get a large area applications and laying. As the infrastructure of the communication, the fiber-optic cable would cause the interruption of communication directly if it was destroyed. So in face of such large number of fiber-optic cable resources, the maintenance and management of the fiber-optic cable has become an important task. But during the construction, the incomplete or inaccurate information of the buried fiber-optic cables make workers can’t find the right positon of the fiber-optic cable, which make the fiber-optic cables easily be destroyed and cause the communication be interrupted. In order to solve this existing problem, this paper studies the fiber optic interferometer loop, takes advantage of the optical fiber sensing technology, such as high sensitivity, anti-electromagnetic interference, large dynamic range, etc, combines the fiber optic interferometry technique with fiber optic distributed sensing technology, proposes a system, fiber optic pathway probing system, which can be used to get the buried fiber-optic cables position information. The system solves the electromagnetic interference problem which is the conventional problem of the electrical sensors. In a specific area, the system can reduce the sound and intensity of the signal which applied to the fiber optic cable with high accuracy and fast response, and get the position information of fiber-optic cables. In the field of maintenance and management of fiber-optic cables, this system has a good prospect.Based on the study of the fiber optic interferometer loop, this paper introduces the fiber optic interferometer loop into the field of fiber optic pathway probing, and constructs the structure of fiber optic pathway probing system. This paper analyses the feasibility of the system from the theoretical level, then makes detailed design of the system. The system consists of an optical transmitter module, an optical element module, an optical receiving module, a signal processing module and a user module. The optical transmitter module provides an optical signal as the information carrier. The optical element module constitutes the fiber optic interferometer loop as the signal transmission medium. The optical receiving module receives and detects the optical signal, and completes the photoelectric conversion. The signal processing module takes control of the entire system and completes the signal processing. The user module provides users with the audio of the signal, the intensity display of the signal, and wireless communication. The entire system can operate simply, in the detection region, the user only need to exert interference signal, such as hammering, and obtain the audio signal and display signal by the user module of the system if the knocking point directly lie above the cable. In this way, users can obtain information about the fiber optic cables pathway.In this paper, FPGA is the hardware platform of the fiber optic pathway probing system. I use the Altium Designer to complete the hardware design of the system, use the Quartus II software to complete the software design of the system, use the C language to control MCU to complete the wireless communication module design, use the Matlab to achieve signal display by serial communication, and build a test environment for each unit module and the entire system to do the performance testing. The experimental results show that the system meets the design requirements, by using the system people can obtain information of the fiber optical cable pathway accurately, so the fiber optic pathway probing system is significant for the maintenance and management of fiber-optic cables. At the end of this paper, I summarizes the design of the entire system, proposes further research direction of the fiber optic pathway probing system.