Guided Plasmon Modes of Elliptical Cross Section Silver Nanoridges

TL;DR

This paper investigates how elliptical cross section silver nanoridges can support and optimize plasmon modes, achieving better confinement and longer propagation distances compared to flat-top nanoridges.

Contribution

It introduces the design of elliptical cross section nanoridges for improved plasmon mode confinement and propagation, identifying the optimal semicircular cross section.

Findings

Elliptical nanoridges can support well-confined plasmon modes with enhanced figures-of-merit.

Optimal waveguide cross section is semicircular, maximizing propagation distance.

High curvature nanoridges resemble wedge plasmon modes.

Abstract

Propagating two-dimensional plasmon modes guided by elliptical cross section silver nanoridges are investigated in this paper. Mode field profiles, dispersion curves, propagation distances, and figure-of-merits of the plasmon ridge modes are calculated for various elliptical cross sections. It is found that an elliptical cross section metal nanoridge, if designed properly, can support a well-confined plasmon mode with a longer propagation distance and a higher figure-of-merit than the flat-top nanoridge plasmon waveguide of the same width. The optimal ridge waveguide cross section is obtained when the elliptical ridge top has a semicircular cross section. When the curvature of the elliptical nanoridge is large, the mode approaches the tightly confined wedge plasmon mode.