Developing the Plasmonic Fractal Nanoantenna for Energy Harvesting and Biosensing Application

In this paper, a Plasmonic arc-shaped nanoantenna is modeled and developed for light trapping and energy enhancement with the multi-Fano response for the mid-infrared spectra in the range of 2000-6000 μm. A symmetric model is suggested to achieve Fano line-shapes and make a hot spot to increase the electric field intensity. Fano response is gained by adding inner parasitic arc elements to the primary Plasmonic ring antenna. Then, the triple jounced ring structure is utilized to improve the electric field intensity. The final nanoantenna depicts that we can improve the electric field with this current nanoantenna with multi-Fano characteristics in comparison to the single Fano response. The maximum electric field efficiency is obtained 450 times which shows more than 300% enhancement in comparison to a simple ring nanoantenna. The efficiency of 650 times obtained with slant polarization.  The sensitivity of the external biological material is checked for the single and multi-Fano elements. The maximum value of sensitivity for the final nanoantenna is 1458 nm/RIU. The multi-Fano has advantages for trapping energy in wider bandwidth and limiting the energy losses in the Plasmonic and Fano resonance.