Near-field focus steering along arbitrary trajectory via multi-lined distributed nanoslits

Abstract

The modulation of near-field signals has recently attracted considerable interest because of demands for the development of nano-scale optical devices that are capable of overcoming the diffraction limit of light. In this paper, we propose a new type of tuneable plasmonic lens that permits the foci of surface plasmon polariton (SPP) signals to be continuously steered by adjusting the input polarization state. The proposed structure consists of multi-lined nanoslit arrays, in which each array is tilted at a different angle to provide polarization sensitivity and the nanoslit size is adjusted to balance the relative amplitudes of the excited SPPs from each line. The nanoslits of each line are designed to focus SPPs at different positions; hence, the SPP focal length can be tuned by modifying the incident polarization state. Unlike in previously reported studies, our method enables plasmonic foci to be continuously varied with a smooth change in the incident linear polarization state. The proposed structures provide a novel degree of freedom in the multiplexing of near fields. Such characteristics are expected to enable the realization of active SPP modulation that can be applied in near-field imaging, optical tweezing systems, and integrated nano-devices.

Tunable Multiple Surface Plasmonic Bending Beams into Single One by Changing Incident Light Wavelength

“…Various SPBs, including focused SPPs [15], Airy beams [16][17][18], Arbitrary bending beams [4,19,20], Weber beams, and Mathieu beams [21], have been realized by various artificial microstructures (such as hole array [4,17,22], grains array [19], two-dimensional binary phase mask gratings [4,19], and polymethyl methacrylate microsphere [23,24]). Dynamic focusing SPPs [25,26] were also realized by circular vertical slit array [27] and circular cross slit array [28]. These nanostructures, as polarization-sensitive nanostructures, were designed by utilizing phase modulation method [20], and can independently control phase and amplitude of SPPs by controlling parameters, size, and arrangement of structures [23][24][25][26][27][28][29].…”

“…Dynamic focusing SPPs [25,26] were also realized by circular vertical slit array [27] and circular cross slit array [28]. These nanostructures, as polarization-sensitive nanostructures, were designed by utilizing phase modulation method [20], and can independently control phase and amplitude of SPPs by controlling parameters, size, and arrangement of structures [23][24][25][26][27][28][29]. However, their size is very small, and it is still a challenge to simultaneously generate the randomly multiplexed polarization states.…”

Progresses in the practical metasurface for holography and lens

“…Mostly, this nature has been utilized in abrupt phase discontinuities, generation of desired surface wave, sweeping polarization states with intensity, and creation of desired dispersive properties [18][19][20][21][22][23][24][25][26][27][28]. The metasurfaces first were exploited a lot for the desired wavefront control for the substitution of optic components with high-performance and ultrathin counterparts, such as hologram generation, lensing, and beam router [6,[29][30][31][32][33][34][35][36][37][38]. These properties have developed to go beyond the conventional device, such as polarization multiplexing, on-chip plasmonic polarimetry, multiwavelength functionality, and dispersion engineering [19,22,[39][40][41][42][43][44].…”

Controllable multiple plasmonic bending beams via polarization of incident waves

“…Controlling plasmonic complex fields by polarization-sensitive nanostructure arrays are important for enriching the components of nanophotonic devices to analyze the polarization [29,30]. Various polarization-sensitive nanostructure arrays, such as aperture arrays [29], Fshaped nanoslits [30], Δ-shaped nanoantennas [31], and double-lined distribution nanoslits arrays [32,33], were designed to manipulate propagation directional of SPP waves. Multilined distributed nanoslits arrays were designed to achieve focused SPPs [32][33][34].…”

“…Various polarization-sensitive nanostructure arrays, such as aperture arrays [29], Fshaped nanoslits [30], Δ-shaped nanoantennas [31], and double-lined distribution nanoslits arrays [32,33], were designed to manipulate propagation directional of SPP waves. Multilined distributed nanoslits arrays were designed to achieve focused SPPs [32][33][34]. Crossshaped nanoantennas were designed to generate double focused SPPs [35].…”