Superfocusing modes of surface plasmon polaritons in
conical geometry based on the quasi-separation of
variables approach

Kazuyoshi Kurihara, Akira Otomo, Atsushi Syouji, Junichi Takahara,
Koji Suzuki, Shiyoshi Yokoyama

Abstract
Analytic solutions to the superfocusing modes of surface plasmon polaritons in a conical geometry are theoretically studied using an ingenious method called the quasi-separation of variables. This method can be used to look for fundamental solutions to thewave equation for a field that must satisfy boundary conditions at all points on the continuous surface of tapered geometries. The set of differential equations exclusively separated from the wave equation can be consistently solved in combination with perturbation methods. This paper presents the zeroth-order perturbation solution of conical superfocusing modes with azimuthal symmetry and graphically represents them in electric field-line patterns.

PACS numbers: 02.30.Mv, 41.20.Gz, 78.20.-e, 78.20.Bh

doi:10.1088/1751-8113/40/41/015