Second-harmonic generation in subwavelength graphene waveguides

We suggest a novel approach for generating second-harmonic radiation in subwavelength graphene waveguides. We demonstrate that quadratic phase matching between the plasmonic guided modes of different symmetries can be achieved in a planar double-layer geometry when conductivity of one of the layers becomes spatially modulated. We predict theoretically that, owing to graphene nonlocal conductivity, the second-order nonlinear processes can be actualized for interacting plasmonic modes with an effective grating coupler to allow external pumping of the structure and output of the radiation at the double frequency.Comment: 5 pages, 3 figure

Broadband light coupling to dielectric slot waveguides with tapered plasmonic nanoantennas

We propose and theoretically verify an efficient mechanism of broadband coupling between incident light and on-chip dielectric slot waveguide by employing a tapered plasmonic nanoantenna. Nanoantenna receives free space radiation and couples it to a dielectric slot waveguide with the efficiency of up to 20% in a broad spectral range, having a small footprint as compared with the currently used narrowband dielectric grating couplers. We argue that the frequency selective properties of such nanoantennas also allow for using them as ultrasmall on-chip multiplexer/demultiplexer devices

Localization of Two-Component Bose-Einstein Condensates in Optical Lattices

We reveal underlying principles of nonlinear localization of a two-component Bose-Einstein condensate loaded into a one-dimensional optical lattice. Our theory shows that spin-dependent optical lattices can be used to manipulate both the type and magnitude of nonlinear interaction between the ultracold atomic species and to observe nontrivial two-componentnlocalized states of a condensate in both bands and gaps of the matter-wave band-gap structure.Comment: 4 pages, 4 figure

Self-trapping of light and nonlinear localized modes in 2D photonic crystals and waveguides

We overview our recent results on the nonlinear localized modes in two-dimensional (2D) photonic crystals and photonic-crystal waveguides. Employing the technique based on the Green function, we describe the existence domains for nonlinear guided modes in photonic crystal waveguides and study their unique properties including bistability. We also show that low-amplitude nonlinear modes near the band edge of a reduced-symmetry 2D square-lattice photonic crystals, which are usually unstable, can be stabilized due to effective long-range linear and nonlinear interactions.Comment: 20 pages (LaTeX) with 12 figures (EPS

Beaming effect from increased-index photonic crystal waveguides

We study the beaming effect of light for the case of increased-index photonic crystal (PhC) waveguides, formed through the omission of low-dielectric media in the waveguide region. We employ the finite-difference time-domain numerical method for characterizing the beaming effect and determining the mechanisms of loss and the overall efficiency of the directional emission. We find that, while this type of PhC waveguides is capable of producing a highly collimated emission as was demonstrated experimentally, the inherent characteristics of the structure result in a restrictively low efficiency in the coupling of light into the collimated beam of light.Comment: 4 pages, 5 figures, submitted to Applied Physics