We propose and demonstrate a 64-channel SiN-Si dual-layer optical phased array (OPA). By taking advantages of both SiN and Si materials, high-power handling and efficient modulation could be achieved simultaneously. In addition, steering range and emission loss are improved by introducing the non-uniform dual-layer antenna. Thinned array efficiently utilized in microwave phased array is first introduced to the OPA. Design details and the corresponding simulation results are presented, and the proposed OPA is successfully fabricated and experimentally characterized. 2D scanning with a steering range of 120°×13.9° and with a resolution of 0.052°×2.72° is demonstrated and a total loss of 12.66 dB is also measured, making it promising for high-resolution long-distance light detection and ranging (Lidar) applications.