The Control And Application Of Fano Resonances In Surface Plasmonic Polaritons System

In recent decades,the Fano resonance in the surface plasmon polaritons system has become a very important research aspect in plasmonic optics due to its minimum distance between the resonance peak and the resonance dip.Surface plasmon polaritons systems which produce one or more Fano resonances have been designed in recent years.Multi-Fano resonance systems are becoming increasingly important and gain more attention due to the advantages in biochemical sensing,spectroscopy and multicolor nonlinear processes.However,it is difficult to control the multiple Fano resonances independently due to the collective effects of the plasmonic structure,which brings great difficulty to the design of the multi-Fano resonance structure.In this paper,several multi-Fano resonance structures that can be independently modulated are designed based on the specific controlling methods of Fano resonance.The main contents are as follows.First,we design an independently tunable double-Fano resonances system which has good applications in the sensing.The resonator system is made up of a cross rectangular cavity on two metal-insulator-metal(MIM)waveguides separated by a metal baffle.The positions of double-Fano resonances in the transmission spectrum can be manipulated independently by changing the size of the horizontal rectangular cavity.We also calculate the refractive index sensitivity and quality factor,which are two important parameters in the sensing.The results show that Maximum refractive index sensitivity and quality factor can be up to 1040nm/RIU and 198.9.Second,we design a four-Fano resonances system,and analyze the controlling characteristics of each Fano resonance.We add another cross rectangular cavity based on the double Fano resonances system.Four resonances appear in the transmission spectrum.This system can be achieved by independent modulation of three Fano resonances.At the same time,we find that we can achieve a specific multi-band sensor or molecular detection device by filling medium with different refractive index in the upper and lower cross rectangular cavity.Third,we design a band-stop filter which can be freely controlled in a certain wavelength range.We add a side-coupled rectangular resonator below the single-sided double-toothed filter,which can also produce a Fano resonance on the left side of the filter window.The Fano resonance on the left and right can be controlled independently by changing the length of the rectangular cavity and the length of the slot resonator.We can further freely modulate the center wavelength and filter bandwidth of the filter within a certain wavelength range.Meanwhile,we can also control the positions of the Fano resonance by changing the filling medium with different refractive index in the rectangular cavity,which brings great convenience to our precise design of the specific wavelength r-ange band-stop filter.