Cascaded Angle-of-Arrival Detection for Wide-Field Optical Phased Array PAT Systems

Integrated optical phased array (OPA) chips enable high-speed beam steering via electronic phase control, providing a promising solution for compact pointing, acquisition, and tracking (PAT) systems. However, OPA-PAT systems must simultaneously achieve wide-field-of-view (FOV) coverage and high-precision angle-of-arrival (AOA) detection. To address this challenge, a cascaded AOA detection method based on a multi-sensor collaborative architecture is proposed. This approach utilizes a distributed detector array (DA) for coarse incident angle estimation over a wide-FOV, which then guides a two-dimensional (2D) galvanometer to steer the beam into a quadrant detector (QD) for fine measurement within a narrow-FOV. A prototype system is developed to validate the proposed cascaded algorithm. Experimental results show that within a ±20° FOV, the proposed system achieves root-mean-square errors (RMSEs) of 0.007° in azimuth and 0.01° in elevation. When integrated into an OPA-PAT terminal, static 2D closed-loop tracking is maintained with an overall tracking error better than 0.016° (RMSE). These results demonstrate that the proposed cascaded detection method can simultaneously provide wide-FOV coverage and high-precision AOA measurement, offering a practical solution for wide-FOV OPA-PAT systems.