Transformational Plasmon Optics

TL;DR

This paper applies transformation optics to control surface plasmon polaritons (SPPs), enabling tailored confinement and propagation on curved surfaces without altering metal properties, leading to novel near-field optical devices.

Contribution

It introduces a method to manipulate SPPs using transformation optics by controlling dielectric properties, facilitating practical, broad-wavelength, and curved surface applications.

Findings

Managed SPP confinement and propagation via dielectric control

Designed plasmonic waveguide bend and Luneburg lens

Achieved broad-band, low-loss SPP guidance on curved surfaces

Abstract

Transformation optics has recently attracted extensive interest, since it provides a novel design methodology for manipulating light at will. Although transformation optics in principle embraces all forms of electromagnetic phenomena on all length scales, so far, much less efforts have been devoted to near-field optical waves, such as surface plasmon polaritons (SPPs). Due to the tight confinement and strong field enhancement, SPPs are widely used for various purposes at the subwavelength scale. Taking advantage of transformation optics, here we demonstrate that the confinement as well as propagation of SPPs can be managed in a prescribed manner by careful control of the dielectric material properties adjacent to a metal. Since the metal properties are completely unaltered, it provides a straightforward way for practical realizations. We show that our approach can assist to tightly bound SPPs over a broad wavelength band at uneven and curved surfaces, where SPPs would normally suffer significant scattering losses. In addition, a plasmonic waveguide bend and a plasmonic Luneburg lens with practical designs are proposed. It is expected that merging the unprecedented design flexibility based on transformation optics with the unique optical properties of surface modes will lead to a host of fascinating near-field optical phenomena and devices.