Sub wavelength plasmonic nano-antenna with modified SRR structure for Fano resonance

The optical electric field enhancement in the normal direction is noticed for Plasmonic and Fano mode at Nano antenna, therefore, we have modeled four various designs for Sub-wavelength Plasmonic and Nano-antenna with modified Split Ring Resonator (SRR) by adding new capacitors and SRR element to achieve the Fano resonance mode in various incident wave angles. Here, for all structures, the E-field enhancements at resonances are compared and design parameters effect on Fano resonance is debated. The incident wave direction is studied for making multi Fano resonance in all prototype structures and the extinction cross section comparison for 0°, 45° and 90° is revealed that the FANO resonances are related to the polarization angle of the incident wave and size of the gaps in Nano particles. SiN Substrate is selected with refractive index of 1.98 and silver with Johnson optical characteristic has been used for modeling of the metal layer. It has been observed that the |E2|/|Eint2| increased to 200 000 at Fano resonances and the parametric studies showed that the gap size controls the Fano resonance frequency.