Study of the interaction of surface waves with a metallic nano-slit via the finite-difference time-domain method

Liste des illustrations

• Fig. 1 Position of the E and H fields inside a Cubic unit cell of the Yee space lattice
• Fig. 2 Schematic of the Total field / Scattered field regions in the 2D main grid
• Fig. 3 Field components positions in the main and auxiliary grids for the TE_z mode with plane wave generated at the left TF/SF interface. Where i0, i1, j0 and j1 denotes the i and j coordinates of the boundaries of the four TF/SF interfaces.
• Fig. 4 Temporal amplitude (a) and spectrum (b) of the pulse (λ ₀ = 800nm, T _FWHM = 10fs)
• Fig. 5 Light intensity patterns after the pulse (λ ₀ = 800nm, T _FWHM = 10fs) has travelled through the phase mask located at the top of the grid
• Fig. 6 Plane wave originating in medium A incident upon a lossy half-space B
• Fig. 7 Computation grid surrounded by PML absorbing boundary conditions
• Fig. 8 Absolute values of the Real and Imaginary parts of the dielectric function of silver as a function of excitation frequency. Circles: experimental data values taken from Ref. [15]. Solid line: dielectric function given by the Drude model. Dotted line: dielectric function given by the Lorentz-Drude model.
• Fig. 9 Half-space configuration for the surface plasmon polariton calculation. The dielectric in medium 1 occupies z > 0; while the metal is in medium 2, z < 0.
• Fig. 10 Dispersion relations of the bulk plasmon polariton (dotted) and surface plasmon polariton (solid) for Ag/vacuum interface. The photon line (dashed) and the surface plasmon line (dash-dotted) are also plotted. This normalized graph is valid for any Drude metal described by Eq. (3.1).
• Fig. 11 Expanded scale plot of Fig 10. Dispersion relation of the surface plasmon polariton (solid) for silver/vacuum interface, photon line (dashed) and surface plasmon line (dash-dotted).
• Fig. 12 Various metallic nanostructures: (a) hole arrays [3]; (b) slit/hole flanked by corrugations [25]; (c) double-slit and [4] (d) groove-slit.
• Fig. 13 Transmission measurement using single-cell probes
• Fig. 14 Light intensity distribution through a 50nm aperture in a 380nm thick aluminum film with input corrugations of 500nm period, mark space ratio 0.5 and grooves’ depth 50nm for (a) λ ₀ = 480nm, (b) λ ₀ = 560nm
• Fig. 15 Transmission measurement using a semi-circular detector at the exit and a plane detector at the entrance
• Fig. 16 Discretization of the semi-circular detector using square cells. No radially radiating field component is computed twice
• Fig. 17 Model schematic (a). Slit transmission T_s (b) with a single beam incident on the groove, as a function of SPP propagation distance L.
• Fig. 18 Module of E _x , E _y , and H _z when a single SPP is incident on slit (a) width a=500nm at resonance; (b) a =380nm out of resonance; (c) a=250nm at resonance. (d): Phase distribution for a= 250nm. In all figures: slit thickness t=300nm and SPP propagation distance L=520nm.
• Fig. 19 Poynting S (blue arrows) and surface current density vectors J (red arrows) for (a) single normal incident beam and (b) single incident SPP illuminations. The length of arrows is proportional to the amplitude. Signs +/– indicate polarities of accumulated electric charges, which are related to the gradient of J . Slit width a=250nm, thickness t=300nm.
• Fig. 20 Variation of (a) squared transmitted intensity normalized with slit width a for various slit widths a and thicknesses t for a sole incident SPP. Standing-wave fringes inside the slit in (b) vertical F-P modes (a=120nm, t=1μm) and (c) horizontal F-P modes (a=1μm, t=310nm).
• Fig. 21 Slit transmittance T _s (normalized on the transmission of a single normal beam on the slit) as a function of the slit-groove distance L.