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

Abstract

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 (δθ) 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.