Nonlocal effects in a hybrid plasmonic waveguide for nanoscale confinement

Abstract

The effect of nonlocal optical response is studied for a novel silicon hybrid plasmonic waveguide (HPW). Finite element method is used to implement the hydrodynamic model and the propagation mode is analyzed for a hybrid plasmonic waveguide of arbitrary cross section. The waveguide has an inverted metal nano-rib over a silicon-on-insulator (SOI) structure. An extremely small mode area of~10⁻⁶λ² is achieved together with several microns long propagation distance at the telecom wavelength of 1.55 μm. The figure of merit (FoM) is also improved in the same time, compared to the pervious hybrid plasmonic waveguide. We demonstrate the validity of our method by comparing our simulating results with some analytical results for a metal cylindrical waveguide and a metal slab waveguide in a wide wavelength range. For the HPW, we find that the nonlocal effects can give less loss and better confinement. In particular, we explore the influence of the radius of the rib's tip on the loss and the confinement. We show that the nonlocal effects give some new fundamental limitation on the confinement, leaving the mode area finite even for geometries with infinitely sharp tips.

Hybrid Dielectric-loaded Nanoridge Plasmonic Waveguide for Low-Loss Light Transmission at the Subwavelength Scale

“…At these conditions, our proposed HDLNRPW features not only a much higher FoM but also a larger propagation distance as compared to its conventional hybrid waveguiding counterpart (see Supplementary Information for details). While compared to modified hybrid structures incorporating inverse metallic nanostructures5859, our proposed waveguide enables much lower loss with subwavelengh field confinement. The propagation distance of HDLNRPW, ranging from tens to hundreds of microns, is more than one orders of magnitude greater than that reported in 58.…”

Silicon hybrid nanoplasmonics for ultra-dense photonic integration

“…In addition to the popular structures of silicon hybrid nanoplasmonic waveguides shown in Table 1, various novel designs have been presented more recently for realizing hybrid plasmonic waveguides with e.g., an additional semiconductor strip [28], multiple layers [29-31], angled sidewalls [32][33][34], a trench [35] and a silver nanowire [36]. Some extremely compact silicon hybrid nanoplasmonic waveguides have also been presented [37][38][39]. In Ref.…”

“…In Ref. [38], the model with the nonlocal effect is used in the analysis for an ultrasmall small hybrid plasmonic waveguide.…”

Nonlocal effects on second harmonic generation in nanofilm plasmonic structure

“…less than 10 nm approximately, local solutions to the macroscopic Maxwell's equations can no longer describe their electromagnetic properties accurately whereas the nonlocal optical response of metal should be taken into account [8]. The failure of the local picture originates from the emergence of strong electron-electron interactions in the dielectric response of metals.…”

“…Therefore, the theoretical investigation of plasmonic phenomena in this subnanometer regime requires the implementation of the nonlocal (spatially dispersive) permittivities to model the dielectric characteristics of plasmonic nanostructures, and ultimately a quantum mechanical treatment [10]. Recently, there have been several reports on theoretical analysis of nonlocal effects in plasmonic structures, such as propagation modes in plasmonic guides [8], optical properties of metallic nanowires [9], nanofocusing performance of plasmonic tips [10], etc. All these studies describe electron-electron interactions through the so-called hydrodynamical model, which introduces a pressure term in the Drude-like equation of motion of the electron density [10].…”