Subwavelength plasmonic nanoantenna as a Plasmonic Induced Polarization Rotator (PI-PR)

Qaisar Hayat,Khizar Hayat,Chong He,Ronghong Jin,Junping Geng,Xianling Liang

doi:10.1038/s41598-020-59621-z

Qaisar Hayat, Khizar Hayat + Show 4 more

Open Access

https://doi.org/10.1038/s41598-020-59621-z

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Abstract

This article reports the finding of the plasmonic induced polarization rotation and propagation rotation when the plane EM wave radiates the adjacent active coated nano particle and large dielectric sphere at resonant frequency. The results investigate that the incident electromagnetic planewave excites the TM21 mode in the large size dielectric sphere at first, which affects the TM11 mode field from the coated nano particle. Consequently, when the combined active coated nano particle and large dielectric sphere are in resonant, the main E–field polarization direction becomes parallel to the propagation direction of the original planewave and main beam of the pattern becomes omnidirectional i.e. both rotates by 90°. Furthermore, the polarization and propagation rotation angle varies with different size of the dielectric sphere. Likewise, the structure of dielectric sphere clamped by two active nanoparticles is also showing plasmonic induced polarization and propagation rotation along with TM11 mode from each coated nano particle (CNP) having 180° phase difference. In addition to this, the induced polarization rotation was also verified by the Electric Hertzian Dipole (EHD). The integration of this simpler geometry with other optical devices has possible applications in polarization manipulation, nano-sensors and detectors on nanoscale.

Highlights

Surface plasmon resonance has attracted more attentions in previous decade due to its wide range of applications in terahertz frequency regime like sensors, amplifiers, information technology, biomedicine, imaging and spectroscopy[1,2,3,4,5,6,7]
The basic resonating model of spherical active Coated Nano Particle (CNP) comprise of silver in shell and the silica doped with Er3+ fills the core material
A single coated nano particle (CNP) attached to a dielectric SiO2 constructs the single CNP Plasmonic Induced Polarization Rotator (PI-power ratio (PR))

Summary

Introduction

Surface plasmon resonance has attracted more attentions in previous decade due to its wide range of applications in terahertz frequency regime like sensors, amplifiers, information technology, biomedicine, imaging and spectroscopy[1,2,3,4,5,6,7]. The problem facing by these polarization rotators is their definite thickness restrictions and relatively bulky configurations. Incorporating these polarization controllers in an ultra-thin device will be of great concern to associate linear and circular polarization with nano-photonic devices and nano sensors[13]. We are proposing a subwavelength size plasmonic nanoantenna capable of manipulating polarization as well as propagation of optical light by 90°. The plasmonic induced polarization rotation in spherical active CNP model is observable in case when this model is placed in the vicinity of a size optimized resonating dielectric sphere. The proposed model i.e. the combination of spherical active CNP attached to the resonating dielectric is termed as plasmonic induced polarization rotator (PI-PR) model

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