Plasmonic channel waveguides in random arrays of metallic nanoparticles

Abstract

We report detailed characterization of surface plasmon-polariton guiding along 1-, 1.5- and 2-μm-wide channels in high-density (~75 μm^-2) random arrays of gold 70-nm-high and 50-nm-wide nanoparticles fabricated on a 70-nm-thin gold film supported by a 170-μm-thick silica substrate. The mode propagation losses, effective index dispersion, and scattering parameters are characterized using leakage-radiation microscopy, in direct and Fourier planes, in the wavelength range of 740-840 nm. It is found that the mode supported by 2-μm-wide channels propagates over > 10 μm in straight waveguides, with the corresponding S-bends and Y-splitters functioning reasonably well. The results show that the SPP waves can efficiently be guided by narrow scattering-free channels cut through randomly corrugated surface regions. The potential of this waveguiding mechanism is yet to be fully explored by tuning the scattering mean-free path and localization length via the density and size of random nanoparticles. Nevertheless, the results obtained are encouraging and promising diverse applications of these waveguide components in plasmonic circuitry.

Metasurface-Based Polarimeters

“…Metasurfaces composed of disordered structure have been demonstrated to realize various functions, such as diffusing light [29], absorbing light [83], waveguiding [84], wavefront shaping [85][86][87], and polarimetry [88]. In Reference [88], a unique on-chip spectropolarimeter, by fingerprinting with a random gold nanoparticle (NP) array, in the near-infrared range is presented.…”

Metasurfaces: Physics and Applications

“…At microwave frequencies, multi-layered unit cells have been reported to achieve high efficiency [82,83]. The scatterers and their composite metasurfaces are usually simulated by numerical simulation software, such as finite element method and finite integration technique-based CST Microwave Studio [84][85][86][87][88][89], finite element method-based HFSS, finite-difference time-domain method-based Lumerical [90], and COMSEL. Some of them can be analytically modelled [87] or simulated by approximate models [84,89].…”

“…The scatterers and their composite metasurfaces are usually simulated by numerical simulation software, such as finite element method and finite integration technique-based CST Microwave Studio [84][85][86][87][88][89], finite element method-based HFSS, finite-difference time-domain method-based Lumerical [90], and COMSEL. Some of them can be analytically modelled [87] or simulated by approximate models [84,89]. Lately, an efficient modelling is applied to integral equation solvers to accelerate the simulation of metasurfaces in multiscale [91].…”

Plasmonic directional couplers using channel waveguides in random arrays of metal nanoparticles

“…In this work, we consider a completely new alternative for the PDC design, which is based on two channel waveguides embedded in random arrays of metal nanoparticles (NPs) separated by a stripe filled also with NPs. The proof of concept for this type of waveguides was investigated in the previous work with straight waveguides, bends and splitters being designed and experimentally characterized [24]. The fundamental idea behind such structures is that the NP-free channels support plasmonic guided modes, while the SPP propagation through random and strongly interacting NPs is prohibited due to the SPP elastic multiple scattering resulting in the SPP localization [25][26][27][28].…”