Focusing polarization diversity grating couplers in silicon-on-insulator

Abstract—We report on compact focusing polarization diversity grating couplers in silicon-on-insulator, which can be used to over-come the polarization dependence of nanophotonic integrated cir-cuits. The minimum fiber-to-fiber polarization dependent loss is 0.4 dB and the focusing grating couplers are as performant as stan-dard 2-D-grating couplers without focusing. In addition, the fo-cusing property of the gratings results in an 8-fold length reduc-tion of the coupling structure as compared to standard nonfocusing 2-D-grating versions. Index Terms—Focusing grating, integrated optics, polarization diversity, silicon-on-insulator. I