Figure 2
From: On-chip photonic Fourier transform with surface plasmon polaritons
(a) SEM micrograph of the plasmonic nanostructure in the angular spectrum of a PWB (a = 40), consisting of slits (240 nm in width) perforated into a 300 nm thick silver film and fabricated by FIB (Zeiss, 30 kV). The radial spatial shift with respect to reference arc (radius of 15 μm) determines the relative phase in the angular spectrum. The incident beam (λ = 632.8 nm) is z-polarized and illuminates the nanostructure from the substrate side. (b) NSOM measurement and (c) FDTD calculations results of electric field intensity distributions, showing excellent agreement in-between. The snapshots of the beam profiles at various propagation distances from 0 to 5 µm in a step of 1 µm obtained from theory, NSOM, and FDTD are shown in (d), (e), and (f), respectively. (g) Comparison of the normalized intensity distribution in the focal line (z = 0) in the cases of theory, NSOM, and FDTD.
