Fano Resonance in Waveguide Coupled Surface Exciton Polaritons: Theory and Application in Biosensor.

Jiaqi Zhu,Banxian Ruan,Xiaoyu Dai,Leiming Wu,Houzhi Cai,Yuanjiang Xiang,Shuaiwen Gan

doi:10.3390/s18124437

Abstract

Surface exciton polaritons (SEPs) are one of the three major elementary excitations: Phonons, plasmons and excitons. They propagate along the interface of the crystal and dielectric medium. Surface exciton polaritons hold a significant position in the aspect of novel sensor and optical devices. In this article, we have realized a sharp Fano resonance (FR) by coupling the planar waveguide mode (WGM) and SEP mode with Cytop (perfluoro (1-butenyl vinyl ether)) and J-aggregate cyanine dye. After analyzing the coupling mechanism and the localized field enhancement, we then applied our structure to the imaging biosensor. It was shown that the maximum imaging sensitivity of this sensor could be as high as 5858 RIU−1, which is more than three times as much as classical FR based on metal. A biosensor with ultra-high sensitivity, simple manufacturing technique and lower cost with J-aggregate cyanine dye provides us with the most appropriate substitute for the surface plasmon resonance sensors with the noble metals and paves the way for applications in new sensing technology and biological studies.

Highlights

In the past several years, research on polariton has drawn great attention due to the mature development between experiment and theory
The plasmon polaritons have been studied extensively in visible wavelengths, and the phonon polaritons are widely researched in the infrared region [2,3,4,5,6], but the novel biosensors are seldom researched based on exciton polaritons
We propose a multilayer thin film biosensor based on Fano resonance (FR), and, as far as we know, the coupling between surface exciton polariton (SEP) mode and waveguide mode (WGM) has not been studied so far in the visible spectrum

Summary

Introduction

In the past several years, research on polariton has drawn great attention due to the mature development between experiment and theory. The plasmon polaritons have been studied extensively in visible wavelengths, and the phonon polaritons are widely researched in the infrared region [2,3,4,5,6], but the novel biosensors are seldom researched based on exciton polaritons. In 2017, Kentaro Takatori et al proposed novel surface exciton polariton (SEP). Its most notable feature is that J-aggregate cyanine dye is a simple fabrication technique, and, from its polar solution, it can be deposited on the substrate by means of spin-coating and dip-coating at room temperature [7]. As regards TDBC, much research has been done on the strong coupling between TDBC and other modes [8,9,10].

Methods

Results

Conclusion