Abstract : Among the various categories of fiber optic sensors, fiber optic phase sensors (i.e., various fiber optic interferometers) have the highest sensitivity. This paper studies a fiber optic sensing system based on a Mach-Zehnder interferometer loop interferometer. This system achieves long-distance, fully distributed positioning detection through techniques such as spectral analysis. The sensing system mainly consists of four parts: an optical plate, a polarization control module, a data processing module, and a user interface. The optical plate, used to generate and receive optical signals, is the main focus of this paper. In this paper, we first analyze various noise sources in the optical receiving section and their causes, and calculate the mathematical approximate results of the noise performance of ordinary receivers, balanced receivers, and self-balancing receivers. Furthermore, we use mathematical simulation tools to analyze and compare the signal-to-noise ratio of the three receivers. Finally, we select the self-balancing receiver scheme for the optical plate. Secondly, we design the circuit schematic of the self-balancing receiver and use the simulation tool Multisim2001 to simulate and analyze the designed circuit, confirming that the circuit can achieve the desired effect. Keywords : Fiber optic sensor; Mach-Zehnder interferometer; self-balancing receiver; thermal noise; shot noise; signal-to-noise ratio 1. Introduction A sensor is a device or apparatus that senses a specified measurand and converts it into a useful signal according to a certain rule. With the development of sensors towards greater sensitivity, precision, adaptability, intelligence, and networking, fiber optic sensors, as a new member of the sensor family, are increasingly favored due to their superior performance. Among the various classifications of fiber optic sensors, fiber optic phase sensors (i.e., various fiber optic interferometers) have the highest sensitivity. This thesis studies a fiber optic sensing system based on a Mach-Zehnder interferometer loop interferometer. This system achieves long-distance, fully distributed positioning detection through techniques such as spectral analysis. The sensing system mainly consists of four parts: an optical plate, a polarization control module, a data processing module, and a user interface. The optical plate is used to generate and receive optical signals and is the main focus of this thesis. [Full text download of the research on the optical plate receiver in the interferometric fiber optic sensing system]