双开口劈裂方环/方形环中磁法诺共振的调控

基于有限元法,从理论上研究了双开口劈裂方环/方形环纳米结构(double split ringsquare ring,DSR-SR)中的等离子体共振和局域电磁场增强等光学特性.由于方形内环的亮模式和双开口劈裂环的暗模式的相互干涉,在该结构中产生了磁法诺共振现象,通过改变该结构的几何参数,可以实现对共振峰位置和强度的有效调控.计算结果表明,该结构中的共振峰对周围介质折射率变化敏感,品质因子最高可达到25.3,并且各共振峰处的局域电场和局域磁场都有很大增强.基于该结构的这些性质,它可以应用于传感器、多光谱表面增强光谱学、低损耗的磁性等离激元的传播和其他基于磁性法诺的光学器件.

Manipulation of magnetic Fano resonance in the double split ring-square ring

The optical properties of plasmon resonances and localized magnetic field enhancement in the double split ring-square ring are investigated by using the finite element method. Magnetic Fano resonances appear in the nanostructure due to the couplings between the bright modes of the square ring couple and the dark modes of the double split ring. The position and intensity of Fano resonances can be tuned by changing the parameters of the nanostructure. The simulated result shows that the resonance peaks of the nanostructure are sensitive to the refractive index of the surrounding environment,and the maximum figure of merit( FOM) reaches 25. 3. In addition,the localized electric and magnetic field of resonance peaks is enhanced. According to the optical properties of the nanostructure,it has great potential application in bio-sensors,multi-wavelength surface-enhanced spectroscopy,the plasmonic propagation with low magnetic loss and other advanced devices based on magnetic Fano resonances.