Research on Coherent Detection Technology of Four Quadrant Photodetectors Based on Monte Carlo Method

Space gravitational wave detection reflects the optical path changes between satellites by sensing small changes in phase information, thereby inverting gravitational wave signals. The gravitational wave detection system places high demands on the four quadrant photodetector as a photoelectric conversion device. The position detection accuracy of the four quadrant detector will greatly affect the perception of phase and optical path information. In order to improve the position detection accuracy of the detector for receiving light spots, this article first builds a mathematical model for spot position detection based on the principle of four-quadrant detector position detection and the Gaussian distribution characteristics of light spots in space laser communication. Secondly, based on the Monte Carlo method, a four quadrant detector coherent detection simulation system is constructed by characterizing the spot power information with random points. Analyze the impact of spot radius, system signal-to-noise ratio, and spot centroid position on position detection accuracy. The simulation results show that increasing the system signal-to-noise ratio, appropriately reducing the spot radius, and placing the spot centroid position close to the detector origin can effectively improve the detector position detection accuracy. And the simulation results are consistent with the theoretical results of the mathematical model, which has certain guiding significance for engineering applications.