title: Metal slit array Fresnel lens for wavelength-scale optical coupling to nanophotonic waveguides.
abstract: We propose a novel metal slit array Fresnel lens for wavelength-scale optical coupling into a nanophotonic waveguide. Using the plasmonic waveguide structure in Fresnel lens form, a much wider beam acceptance angle and wavelength-scale working distance of the lens was realized compared to a conventional dielectric Fresnel lens. By applying the plasmon waveguide dispersion relation to a phased antenna array model, we also develop and analyze design rules and parameters for the suggested metal slit Fresnel lens. Numerical assessment of the suggested structure shows excellent coupling efficiency (up to 59%) of the 10 mum free-space Gaussian beam to the 0.36 mum Si waveguide within a working distance of a few mum.
authors.affiliation: Photonic Systems Laboratory, School of EECS, Seoul National University, Seoul 151-744, Korea.
authors.forename: Young Jin
authors.initials: YJ
authors.lastname: Jung
authors.forename: Dongwon
authors.initials: D
authors.lastname: Park
authors.forename: Sukmo
authors.initials: S
authors.lastname: Koo
authors.forename: Sunkyu
authors.initials: S
authors.lastname: Yu
authors.forename: Namkyoo
authors.initials: N
authors.lastname: Park