A Positioning Method Based on Large-Area Four-Quadrant Photodetector

Four-quadrant (4Q) photodetectors are widely utilized in quick light tracking and positioning through differential signal processing. However, it is a challenge to track light in a large dynamic space with high speed and simple signal processing. In this letter, a positioning method is proposed based on a back-to-back n ⁺ -p ⁻ -p ⁺ -p ⁻ -n ⁺ structure formed by two adjacent quadrants. It is found the turn-on voltage of this particular structure is sensitive to the light incident position when a light spot is located inside a single quadrant. A 1 mm positioning resolution is achieved for a 4Q photodetector with a diameter of 11.3 mm. This method provides a supplementary positioning scheme for a large-area 4Q photodetector that exhibits the advantages of high positioning accuracy and simple signal processing with high speed.