Slit width oriented polarized wavefields transition involving plasmonic and photonic modes

Abstract

Wavefield manipulation of surface plasmon polaritons (SPPs) is one of the fundamental subjects in nanophtonics. In this paper, based on the analyses of the plasmonic and photonic modes of the L-shaped slit samples with different widths, the dependence of the wavevector, amplitude and phase of the scattered wavefields on the slit width are experimentally determined. The excited plasmonic mode and photonic mode wavelets by arbitrary slit element is analyzed theoretically. Au ring-slits with different widths are also experimented as general slit structure to show the polarized patterns originated from the superimposition of the two modes, and the evolution of total and polarized intensity patterns with the ring-slit widths is studied systematically. The wavefield patterns of the polarization components are also calculated with the obtained components of wavefields and Huygens–Fresnel principle, and results of calculations and experiments are coincident. In addition, the results are validated by performing finite-difference time-domain simulations. The work may enhance the efficiency of slit engineering for SPP pattern manipulations and can be a helpful reference for the fabrication of nano-optics devices.

Keywords

• surface plasmons
• polarization
• interference
• scattering