Double-groove rectangular gratings for high-efficiency wideband vertical coupling in planar-integrated optical systems

A planar-integrated optical system(PIOS)represents powerful optical imaging and information processing techniques and is a potential candidate for the realization of a three-dimensional(3D)integrated optoelectronic intelligent system.Coupling the optical wave carrying information into a planar transparent substrate(typically fused silica)is an essential prerequisite for the realization of such a PIOS.Unlike conventional grating couplers for nano-waveguides on the silicon-on-insulator platform,the grating couplers for PIOS enable to obtain a higher design freedom and to achieve much higher coupling efficiency.By combining the rigorous coupled wave algorithm and simulated annealing optimization algorithm,a highefficiency asymmetric double-groove grating coupler is designed for PIOS.It is indicated that,under the condition of the normal incidence of TE polarization,the diffraction efficiency of the-1st order is over 95%,and its average value is 97.3%and 92.8%in the C and C+L bands.The simulation results indicate that this type of grating coupler has good tolerance and is expected to be applied in optical interconnections,waveguide-based augmented reality glasses,and planar-integrated 3D interconnection optical computing systems.