Compact antenna for efficient and unidirectional launching and decoupling of surface plasmons

TL;DR

This paper presents a compact, efficient, and unidirectional surface plasmon launcher using subwavelength grooves, achieving over 52% efficiency and enabling conversion of SPPs into a highly directive light beam.

Contribution

The authors design and experimentally demonstrate a novel compact plasmonic device with high unidirectional launching efficiency and SPP-to-light conversion capabilities.

Findings

Achieves at least 52% unidirectional SPP launching efficiency.

Device length is smaller than 8 micrometers.

Enables efficient conversion of SPPs into a directive light beam.

Abstract

Controlling the launching efficiencies and the directionality of surface plasmon polaritons (SPPs) and their decoupling to freely propagating light is a major goal for the development of plasmonic devices and systems. Here, we report on the design and experimental observation of a highly efficient unidirectional surface plasmon launcher composed of eleven subwavelength grooves, each with a distinct depth and width. Our observations show that, under normal illumination by a focused Gaussian beam, unidirectional SPP launching with an efficiency of at least 52% is achieved experimentally with a compact device of total length smaller than 8 \mu m. Reciprocally, we report that the same device can efficiently convert SPPs into a highly directive light beam emanating perpendicularly to the sample.