Plasmonic Nano-Gap Tilings: Light-Concentrating Surfaces for Low-Loss Photonic Integration

TL;DR

This paper introduces tunable low-loss plasmonic nano-gap tilings that concentrate light on chip, enabling efficient energy transfer with high field enhancement and long propagation lengths for integrated photonic devices.

Contribution

It presents a novel class of low-loss, tunable metasurfaces with dense nano-gap arrangements that optimize light localization and energy transfer on photonic chips.

Findings

Product of field enhancement, propagation length, and element size is nearly constant.

Different operational regimes identified based on element size.

High field enhancements achieved with large propagation lengths.

Abstract

Owing to their ability to concentrate light on nanometer scales, plasmonic surface structures are ideally suited for on-chip functionalization with nonlinear or gain materials. However, achieving a high effective quantum yield across a surface not only requires strong light localization but also control over losses. Here, we report on a particular class of tunable low-loss metasurfaces featuring dense arrangements of nanometer sized focal points on a photonic chip with an underlying waveguide channel. Guided within the plane, the photonic wave evanescently couples to the nano-gaps, concentrating light in a lattice of hot-spots. In studying the energy transfer between photonic and plasmonic channels of single trimer molecules and triangular nano-gap tilings in dependence on element size, we identify different regimes of operation. We show that the product of field enhancement, propagation length and element size is close-to-constant in both the radiative and subwavelength regimes, opening pathways for device designs that combine high field enhancements with large propagation lengths.