Development of a Specialized Phased Array Photodetector Chip for Grating Encoders Using Phase Difference Filtering

This paper proposes a phased array photodetector chip scheme based on phase difference filtering for grating encoders, aiming to address the bottleneck of traditional grating encoders in balancing precision and miniaturization. The core innovation of the proposed method lies in its optimized signal processing and structural design. The method further subdivides each field in the four-field column method into multiple row combinations with different phases, and weakens high-order harmonic components through the phase arrangement relationship between row combinations, thereby improving the quality of Moiré fringe signals. It meets the demand for a compact array layout while ensuring good photoelectric conversion efficiency. To ensure the scheme’s feasibility and integration, the research adopts a cross-disciplinary integrated approach that combines optics, mechanics, and electronics. It integrates technologies such as phase difference filtering and optoelectronic integration into the development of photodetectors, and designs a dedicated integrated optoelectronic chip based on the developed detector. The research verifies the scheme through a rigorous three-step process: theoretical modeling, structural innovation (to design the folded-line array layout for compactness), and process verification (to ensure compatibility with standard semiconductor manufacturing processes). Simulation results confirm that the developed folded-line array photodetector exhibits excellent orthogonality in photoelectric signal conversion, a key indicator of measurement accuracy. Meanwhile, the chip’s compact array layout reduces its overall volume by approximately 30% compared to traditional discrete detector modules, while maintaining a high photoelectric conversion efficiency of over 85%.