Enhanced emitting aperture in optical phased arrays with weak-coupled grating antennas via large critical dimensions

We propose what we believe to be a novel strategy to design optical phased arrays (OPAs) antennas by inserting a narrow waveguide between the bus waveguide and grating teeth. When the minimum critical dimension (CD) is 200 nm and the grating length is 1.5 mm, we achieve a quite small divergence angle of 0.05°, a reduction from 0.11° using the conventional method with the same CD. This design is compatible with 248 nm deep ultraviolet lithography, offering a more accessible fabrication process. By the gap’s increase from 180 nm to 410 nm rather than minimizing grating tooth dimensions, the divergence angles ( δ θ ) have been demonstrated to be reduced from 0.28° to 0.05°. Furthermore, the designed OPA exhibits well divergence angles consistency, with a low standard deviation of 0.35% across wavelengths ranging from 1500 nm to 1560 nm. This innovation simplifies OPA fabrication, paving the way for cost-effective, high-resolution light detection and ranging (LiDAR) systems with extended detection capabilities.