Unidirectional large-scale waveguide grating with uniform radiation for optical phased array

Two novel waveguide gratings for optical phased array transmitters are investigated. By offsetting the grating structures along the waveguide on the upper and lower surfaces of the silicon nitride (Si3N4) waveguide, the dual-level chain and dual-level fishbone structures can achieve 95% of unidirectional radiation with a single Si3N4 layer by design. With apodized perturbation along the gratings, both structures can achieve uniform radiation without compromising the unidirectional radiation performance. In experiment, both demonstrate similar to 80-90% unidirectionality. With further analysis, it is found that the dual-level fishbone structure is more feasible and robust to process variations in unitirrn radiation. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Two novel waveguide gratings for optical phased array transmitters have been studied, with the dual-level chain and dual-level fishbone structures achieving high unidirectional radiation performance through design, and with apodized perturbation allowing for uniform radiation without compromising performance. Experimental results show both structures reaching 80-90% unidirectionality, with further analysis indicating that the dual-level fishbone structure is more feasible and robust to process variations in achieving uniform radiation.