Research On Fano Resonance In Total Internal Reflection Structure And Its Application In Sensing

Fano resonance has become a research focus of new resonance effects since it was found to have asymmetric resonance lines.Farno resonance originates from the coupling between the super-radiation bright mode in the continuous state and the sub radiation dark mode in the discrete state supported in the structure.Due to its advantages of extremely narrow resonance peak-to-dip spacing,strong near-field enhancement,ultra-high sensitivity and quality factor,Fano resonance has great potential application value in biosensing,surface-enhanced Raman scattering,nonlinear optics and other fields.In this paper,two simple and flexible optical structures are designed to realize Farno resonance or multiple Farno resonances with ultra-high quality factor by using the principle of total internal reflection.The corresponding optical response spectra are calculated numerically,and the physical mechanism of Farno resonance is analyzed.Modulation effects of geometric parameters of designed microstructures,polarization state of incident light,and wavelength of incident light on the optical response of the structure are systematically studied.The main research contents of this paper are as follows:1.Two-dimensional materials coupled optical waveguide in total inernal reflection structure:Two waveguide modes are excited inthis structure by using prim's total internal reflection.By introducing molybdenum disulfide and graphene respectively,the two waveguide modes exhibit a broad and a narrow resonance respectively,so that the excitation of Fano resonance characterized by narrow and asymmetric spectral line shape can be realized after their coupling.The origin of Fano resonance is explained and demonstrated by numerical calculation.In addition,the modulation on Fano resonance is realized by changing the structural parameters.We finally analyze the two most important parameters of the structure in sensing application,sensitivity and quality factor,and obtain an ultra-high quality factor with molybdenum disulfide and graphene,9630 RIU^-1and 8264 RIU^-1respectively.This structure is a new structure which achieves super high quality factor Fano resonance by coupling the same electromagnetically mode with two-dimensional materials.2.1D-Ph Cs coupled plasmon system in total inernal reflection structure:Multiple Fano resonences can be achieved in this structure by combing plasmon system with a periodic all-dielectric waveguide.By employing semiconductor-based surface plasma material,the excited multiple Fano resonances canbe tuned to near-infrared band.We calculate the electromagnetic field distribution in this structure under each resonance angle to demonstrate and analyze the origin of multiple Fano resonances.In addition,the dynamic tuning on multiple Fano resonances simultaneously is realized via changing structural parameters.Finally,we extend this structure to the whole near-infrared wide band,and achieve the excitation of multiple Fano resonances in a wide angle range at any wavelength in near-infrared wide band.In this structure,nontraditional plasma material?ITO?is used to realize the excitation of multiple Fano resonances in near infrared band.