Optical Fishnets Based on Plasmonic Resonance

This work focuses on a theoretical and rigorous investigation of a particular category of metamaterial structures known as fishnets. Fishnets are composed of alternating layers of metal and dielectric materials, with subwavelength holes arranged in a periodic manner. We aimed to cover the principles of physics and enhance the fishnet structure by modifying its geometric characteristics to get an optimized response, specifically in terms of negative refraction indices inside specific spectrum bands. The optical fishnet structure presented here acts as a mesh-like device that concentrates the electric field within the Nano-etching area, having both width (n) and length (v). The inquiry is proposed using the COMSOL Multiphysics program. The proposed construction was tested within a simulation frequency range of 100--900 THz. The resulting enhancement factors (EFs) displayed different values depending on the various dimensions of the fishnet. Multiple research studies are carried out to figure out the EF of specific structures. The dimensions ranged from 20 to 50 nm, and these dimensions corresponded to EFs ranging from 10 ⁶ to 10 ¹⁰. The more we reduce the dimensions, EFs are enlarged with very high values. This conclusion is presented in detail in this work. The presented structure can be used in many different areas such as surface enhanced Raman spectroscopy, any wave focusing application depending on plasmonic effects.