Optical phased arrays (OPAs) have emerged as a powerful platform for applications spanning light detection and ranging (LiDAR), free-space optical communication, and next-generation wireless networks. Integrated OPAs, in particular, offer the ability to synthesize arbitrary far-field radiation patterns and achieve two-dimensional (2D) beam steering while benefiting from a compact footprint, high mechanical stability, and excellent steering accuracy. Yet, the inherently short wavelength of light imposes stringent constraints on 2D OPA architectures: the integration of electronic phase shifters or routing waveguides within the array aperture complicates dense antenna packing, often introduces parasitic beams, and limits sidelobe performance. Consequently, there is a growing demand for scalable OPAs capable of robust 2D beam steering and high sidelobe suppression without relying on wavelength tuning or randomized antenna placement. In this work, we introduce a deterministic antenna-positioning architecture that enables the design of integrated OPAs with unprecedented sidelobe suppression while preserving scalability. The antennas are sequentially placed across different rows, with their column positions chosen to minimize phase clustering and achieve a phase-equalized distribution for sidelobe suppression while remaining compatible with scalable routing using straight and parallel optical waveguides. As a proof of concept, we realize a 200-channel sparse OPA that achieves 15 dB noise suppression, a beam divergence of 0.16°, size scalability across large apertures, and full 2D sidelobe-free beam steering at a fixed wavelength. These results represent a substantive advance in integrated OPA design and unlock new opportunities for high-performance beamforming in LiDAR, metrology, 5G systems, and free-space optical communication.
