Figure 1

Deep-subwavelength focusing with an aperiodic metallic waveguide array. (a) The device geometry: a plane wave ($1\mu \mathrm{m}$ wavelength) incident upon an aperiodic array of coupled metallic waveguides of varying width (from the side to the center: 46, 54, 62, 70, 78, 84, 90, 94, 98, 100 nm) and constant gold spacing (36 nm). (b) Contour plot of the dispersion relation $k_z(x,k_x)$ throughout the structure; the $k_x$ axis is rescaled (with $P(x)$, the local period) so that for every position $x$ only the first Brillouin zone is shown. (c) Ray tracing inside the structure using Hamiltonian optics. The thick (red) contour and ray are discussed in the main text. FDFD-simulated electric field intensity of the focusing pattern for an incident plane wave (d) and a narrow Gaussian beam (e).Reuse & Permissions

Figure 2

Focusing in an aperiodic metallic waveguide array at longer wavelengths. FDFD simulations (a)–(c), Hamiltonian optics (d)–(f).Reuse & Permissions

Figure 3

Lateral nanosteering with an aperiodic metallic waveguide array. FDFD simulations (a)–(c), Hamiltonian optics (d)–(f).Reuse & Permissions

Figure 4

Focusing with the aperiodic metallic waveguide array from Fig. 1 at shorter and visible wavelengths.Reuse & Permissions