To meet the requirements of non-mechanical beam scanning and acquisition in space laser communication, this study proposes a two-dimensional scanning and acquisition method based on a silicon-based optical phased array (OPA). The OPA utilizes thermo-optic phase modulation to achieve horizontal beam pointing, while vertical beam pointing is controlled by wavelength tuning. By combining the OPA with a rectangular spiral scanning strategy, non-mechanical scanning is realized and beam acquisition experiments are carried out. Experimental results demonstrate that for an 8° step signal, the horizontal and vertical rise times are 156.8 μs and 214.76 ms, respectively. A full scan of 440 points covering a ±4° field of view is completed in 8.119 s. Acquisition experiments were conducted assuming a Gaussian-distributed uncertainty region (standard deviation $\sigma =1°$). Out of 106 independent trials, a success rate of 97.17% was achieved with an average acquisition time of 0.41 s. This work experimentally applies a rectangular spiral scanning strategy to an OPA-based acquisition system, addressing a capability that has been largely missing in previous studies. These results verify that the OPA technology has good scanning efficiency and acquisition robustness in space laser communication applications.

To meet the miniaturization and lightweight requirements of inter-satellite laser communication, this study investigates the servo control system of a silicon-based optical phased array (OPA). Based on the far-field radiation model for beam steering of the silicon-based OPA, combined with thermo-optic phase modulation technology and time domain response, the transfer function of the silicon-based OPA is established. To address noise and disturbances encountered during actual tracking, a silicon-based OPA beam tracking method for satellite platform vibration is proposed. The control algorithm employs a Kalman filter-based Model Predictive Control (KF-MPC) strategy. The advantages of the designed control algorithm were verified through simulations and experiments. Step response simulation results show that compared with the traditional PID control algorithm, the proposed algorithm reduces overshoot by 15.1% and shortens the response time by 76.4%. Sinusoidal tracking simulation results indicate a 27.15% improvement in tracking accuracy over the traditional PID algorithm. Experimental results demonstrate that the tracking accuracy of the servo control system with the proposed algorithm is 155.45 μrad, while that using the PID algorithm is 210.97 μrad, representing a 26.31% improvement in tracking accuracy. This research provides a valuable reference for the application of silicon-based OPA in inter-satellite laser communication.