title: Highly efficient nonuniform grating coupler for silicon-on-insulator nanophotonic circuits.
abstract: We present design, fabrication, and characterization of a silicon-on-insulator grating coupler of high efficiency for coupling between a silicon nanophotonic waveguide and a single mode fiber. By utilizing the lag effect of the dry etching process, a grating coupler consisting of nonuniform grooves with different widths and depths is designed and fabricated to maximize the overlapping between the upward wave and the fiber mode. The measured waveguide-to-fiber coupling efficiency of 64% (-1.9 dB) for the transverse electric polarization is achieved by the present nonuniform grating coupler directly defined on a regular silicon-on-insulator wafer.
authors.affiliation: Joint Research Center of Photonics of the Royal Institute of Technology, Sweden. yongbo@kth.se
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Tang
authors.forename: Zhechao
authors.initials: Z
authors.lastname: Wang
authors.forename: Lech
authors.initials: L
authors.lastname: Wosinski
authors.forename: Urban
authors.initials: U
authors.lastname: Westergren
authors.forename: Sailing
authors.initials: S
authors.lastname: He