title: Stratified waveguide grating coupler for normal fiber incidence.
abstract: We propose a new stratified waveguide grating coupler (SWGC) to couple light from a fiber at normal incidence into a planar waveguide. SWGCs are designed to operate in the strong coupling regime without intermediate optics between the fiber and the waveguide. Two-dimensional finite-difference time-domain simulation in conjunction with microgenetic algorithm optimization shows that approximately 72% coupling efficiency is possible for fiber (core size of 8.3 microm and delta=0.36%) to slab waveguide (1.2-microm core and delta=3.1%) coupling. We show that the phase-matching and Bragg conditions are simultaneously satisfied through the fundamental leaky mode.
authors.affiliation: Nano and Micro Devices Center, University of Alabama in Huntsville, Huntsville, Alabama 35899, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Jianhua
authors.initials: J
authors.lastname: Jiang
authors.forename: Diana M
authors.initials: DM
authors.lastname: Chambers
authors.forename: Jingbo
authors.initials: J
authors.lastname: Cai
authors.forename: Gregory P
authors.initials: GP
authors.lastname: Nordin