Freestanding bilayer plasmonic waveguide coupling mechanism for ultranarrow electromagnetic-induced transparency band generation

Li Yu,Yuzhang Liang,Qiao Wang,Shuwen Chu,Huixuan Gao,Wei Peng

doi:10.1038/s41598-021-81118-6

Li Yu, Yuzhang Liang + Show 4 more

Open Access

https://doi.org/10.1038/s41598-021-81118-6

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Abstract

Strong electromagnetic coupling among plasmonic nanostructures paves a new route toward efficient manipulation of photons. Particularly, plasmon-waveguide systems exhibit remarkable optical properties by simply tailoring the interaction among elementary elements. In this paper, we propose and demonstrate a freestanding bilayer plasmonic-waveguide structure exhibiting an extremely narrow transmission peak with efficiency up to 92%, the linewidth of only 0.14 nm and an excellent out of band rejection. The unexpected optical behavior considering metal loss is consistent with that of electromagnetic induced transparency, arising from the destructive interference of super-radiative nanowire dipolar mode and transversal magnetic waveguide mode. Furthermore, for slow light application, the designed plasmonic-waveguide structure has a high group index of approximately 1.2 × 105 at the maximum of the transmission band. In sensing application, its lowest sensing figure of merit is achieved up to 8500 due to the ultra-narrow linewidth of the transmission band. This work provides a valuable photonics design for developing high performance nano-photonic devices.

Highlights

Strong electromagnetic coupling among plasmonic nanostructures paves a new route toward efficient manipulation of photons
Another prominent example is the combination of periodic gold nanowires with a slab waveguide structure for generating the electromagnetic-induced transparency (EIT) transmission p eak[19,20,21], which is attributed to the coherent coupling of nanowire plasmonic mode and optical waveguide mode
The narrow transmission band arises from the excitation of the waveguide mode through the scattering of localized plasmonic mode in the metal nanowire pairs

Summary

Introduction

Strong electromagnetic coupling among plasmonic nanostructures paves a new route toward efficient manipulation of photons. We provide an extremely narrow EIT transmission band by coupling optical waveguide mode to the broad low-transmission spectrum of plasmonic nanowire pairs in a free-standing bilayer plasmonic waveguide structure.

Results

Conclusion