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.

The Interference Pattern of Plasmonic and Photonic Modes Manipulated by Slit Width

“…The plasmonic mode and photonic mode can be correspondingly excited when they are illuminated by TM (red arrow) and TE (black arrow) polarized light [33][34][35]. The features of these two modes, including amplitude and phase, strongly depend on the slit width [28,33,34]. With commercial software FDTD solutions, the plasmonic mode and photonic mode generated by slits with different widths are analyzed.…”

“…The manipulation of the plasmonic field is an important subject in up-to-date plasmonic optics. To control the plasmonic field, the shapes, widths, and orientations of slits are the elements to control the launched wavelets [18,[24][25][26][27], and the interferences of the wavelets form the wave field patterns [8][9][10][11][12][28][29][30]. The interferences can be described intuitively by the Huygens-Fresnel principle for subwavelength metal slits [31,32], and the principle has facilitated the manipulations of the plasmonic field.…”

“…The two modes have been used in the design of nanoslit lenses with polarization-selective [33]. Generally, the component quantities of excitation efficiencies, the initial phases, and the equivalent wavevectors of the two modes depend highly on the slit widths [28,33,34], and the differences in the quantities would apparently influence the wave field. This dependence and the interference of the wavelets are the foundation for the formation of wavefield patterns.…”

Spin-Independent Plasmonic Lens

“…Surface plasmon polaritons (SPPs) which are hybrid modes of phonons and electronic oscillations propagating along the two dimensional (2D) metal/dielectric interface can be an effective tool to overcome the above limitations [11–17]. With the subwavelength feature, SPPs can be easily focused to a subwavelength spot [18–21]. As the counterpart of the optical lens in the 3D space, semicircular slit plasmonic lens cannot only focus SPP fields but also perform SPP FT with a much faster speed in a 2D plane [4].…”

Dynamical Manipulation of Surface Plasmon Polaritons

“…Particularly, for circularly polarized light, the SPPs generated by subwavelength slits are imprinted with a spin-dependent Pancharatnam-Berry (PB) phase which can be tuned by changing the orientation angle of the slits [46,47]. Polarization-controlled dynamical SPP excitation [48][49][50][51][52][53][54][55][56], SPP focusing [46,[57][58][59][60][61][62][63][64][65][66], SPP vortex [21,44,[67][68][69][70][71][72][73], SPP nondiffracting beams [74][75][76], and SPP holography [77,78] have been 2 of 17 realized. Besides, the other degrees of freedom of light-including the wavelength, topological charge, and the spatial frequency-can be taken advantage of to actively control the SPP field [79][80][81][82][83][84][85][86] as well.…”