Fano Resonances Of Nanostructures And Applications In Tuning Optical Properties Of Monolayer MoS₂

Metallic nanostructures can be excited by incident electromagnetic waves to cause free electrons on the metal surface to oscillate to form localized surface plasmons.Notably,the specific optical properties of metal nanostructures are decided by the shape,size,material,and the state of the incident light.Therefore,more and more optoelectronic devices with specific functionalities have been demonstrated through tuning the optical properties of metallic nanostructures,such as,chiral nanostructures for natural chiral molecule discrimination,and high-refractive index biosensors based on Fano resonances.Especially,Fano resonance,an unique phenomenon only exist in quantum area,has been achieved in metallic nanostructures through plasmonic couplings and find wide applications in biosensors,nanoelectronics,and displays.Two-dimensional materials have attracted much more attention for their unique excellent properties in heat,force,electricity and optics.However,the luminescence characteristics of single-layer MoS₂ are relatively weak which prevent their wide applications in next generation of optoelectronic devices.Therefore,enhancement and manipulation of luminescence of single-layer MoS₂ is a hot research topic.Here,Fano resonances of metallic nanostructures was used to tune the optical properties of single-layer MoS₂.Firstly,Two types of metallic nanostructures with Fano resonance were designed in this paper.The FDTD solution methods was employed to simulate the optical properties of the nanostructures with Fano resonances and to investigate the underlying physics of the Fano resoannces.The plasmonic coupling hybrid model was used to analyze the plasmon coupling mode between different metal nanostructures.Then the morphology parameters of the nanostructures were changed to study the relationship between Fano resonances properties and nanostructure parameters.The advantages and disadvantages of these two metallic nanostructures with respect the Fano resonance,spectral FWHM?Full Width At Half Maximum?,and the intensities of near-field electric fields were compared.Finally,the metallic nanostructures with simple structure and easy tuning were selected to manipulate the optical properties of monolayer MoS₂.Then this paper combined a single-layer MoS₂ with the selected metallic nanostructures and investigated the interaction between Fano resonances and monolayer MoS₂,including the enhancement of photon absorption of MoS₂ and Rabi splitting of Fano resonances.Weak plasmon-exciton coupling was proved and explained the mechanism of photoluminescence enhancement of monolayer MoS₂,This interaction between the metallic nanostructures and MoS₂ can enhance the Fano resonances of the metalicl nanostructure and increase the absorbance of the MoS₂.The thesis is helpful to develop ultrathin,flexible,and high-emissive optoelectronic devices.