Manipulation of Multiple Fano Resonances Based on a Novel Chip-Scale MDM Structure

Zhengfeng Li,Yuwen Qin,Dongyue Zhou,Liang Lei,Yihong Fang,Kunhua Wen,Li Chen,Jinyun Zhou

doi:10.1109/access.2020.2973417

Abstract

A novel chip-scale metal-dielectric-metal (MDM) refractive-index sensor is proposed and investigated in this paper by using finite-difference time-domain (FDTD) method and multimode interference coupled-mode theory (MICMT), respectively. A slot cavity with an embedded tooth-shape cavity and a side-coupled semi-ring cavity are inserted between the input and output MDM waveguides. According to the simulation results, dual ultra-sharp and asymmetrical Fano peaks emerge in transmission spectrum with high performances. Besides, the transmission responses for the primary parameters of this structure are also investigated. To focus on developing integrated photonic devices, the original structure is successfully expanded by two additional semi-ring cavities through an innovative coupling approach, generating up to eight Fano peaks with outstanding characteristics. It is believed that this novel MDM structure will be a guideline for designing the chip-scale plasmonic devices.

Highlights

Fano resonance, which is caused by the coherent interference between a discrete excited state and a continuum in the same energy level [1]–[4], has attracted much attention in the plasmonic fields due to its extensive application prospect in recent years
It is remarkably performing in the optical communication and optical sensing areas owing to its unique characteristics of high sensitivity (S) and high figure of merit (FOM) [5]
By employing finite-difference time-domain (FDTD) method and multimode interference coupled mode theory (MICMT) for the proposed structure, we have investigated dual ultra-sharp and asymmetrical Fano peaks, which are attributed to the mode interactions, and these Fano peaks possess high sensitivities and high FOMs

Summary

INTRODUCTION

Fano resonance, which is caused by the coherent interference between a discrete excited state and a continuum in the same energy level [1]–[4], has attracted much attention in the plasmonic fields due to its extensive application prospect in recent years. Due to the potential applications of Fano resonances, such as enhanced biochemical sensing [2], [19], fast light or slow light devices [3] and optical switching [20], [21], one should expect to make full use of the parallel processing capabilities of multiple Fano resonances, for developing highly integration of photonics In this case, researchers have proposed several MDM structures to generate about three or four Fano resonances in the side-coupled systems [22], [23] or the end-coupled systems [24]. By employing finite-difference time-domain (FDTD) method and multimode interference coupled mode theory (MICMT) for the proposed structure, we have investigated dual ultra-sharp and asymmetrical Fano peaks, which are attributed to the mode interactions, and these Fano peaks possess high sensitivities and high FOMs. multi-channel Fano resonances are successfully achieved by arranging two additional semi-ring cavities to side couple to the waveguides. We believe that this hybrid coupled system will be a typical example for designing multi-Fano resonators in highly integrated photonic circuits

STRUCTURAL MODEL AND SIMULATION ANALYSIS

CONCLUSION