title: High efficiency Silicon-on-Insulator grating coupler based on a poly-Silicon overlay.
abstract: A high efficiency broadband grating coupler for Silicon-On-Insulator waveguides was designed. The grating coupler is defined by locally adding a poly-Silicon layer on top of the existing waveguide layer structure prior to grating etching. Adding this poly-Silicon layer reshapes the grating structure which changes its diffraction properties. Coupling efficiencies as high as 78% at a wavelength of 1.55 mum are calculated and the optical 3dB bandwidth of the device is about 85 nm. The device layout is compatible with standard CMOS technology processing.
authors.forename: Günther
authors.initials: G
authors.lastname: Roelkens
authors.forename: Dries
authors.initials: D
authors.lastname: Van Thourhout
authors.forename: Roel
authors.initials: R
authors.lastname: Baets