title: Gradient-index antireflective subwavelength structures for planar waveguide facets.
abstract: We demonstrate the use of subwavelength gratings etched into the facets of silicon-on-insulator ridge waveguides as a means of reducing facet reflectivity by the gradient-index effect. Reflectivities as low as 2.0% and 2.4% for the fundamental TE and TM modes, respectively, are demonstrated experimentally for light of 1.55 microm wavelength, in agreement with both effective medium theory and finite-difference time domain calculations. Simulations show that facet reflectivites can be further reduced to less than 1% by increasing the grating modulation depth.
authors.affiliation: Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. jens.schmid@nrc-cnrc.gc.ca
authors.forename: J H
authors.initials: JH
authors.lastname: Schmid
authors.forename: P
authors.initials: P
authors.lastname: Cheben
authors.forename: S
authors.initials: S
authors.lastname: Janz
authors.forename: J
authors.initials: J
authors.lastname: Lapointe
authors.forename: E
authors.initials: E
authors.lastname: Post
authors.forename: D-X
authors.initials: DX
authors.lastname: Xu