A Novel Analysis for Light Patterns in Nano Structures

Abstract

Nano antennas have a significant role in photonic nanodevices due to the ability of concentrating radiation in a small space region. The confined fields present a high sensitivity to the used materials in that regions. The electromagnetic wave models of nanoantennas usually operate in the frequency domain. However, electromagnetic wave models in the time domain are just as important and more advantageous, for example, in light pulses propagation. In this article, a new stochastic method based on the ray model of light in absorbing media is presented and light patterns on a target near a nanoantenna are obtained. The optical properties of the materials are described by their complex refractive index. When dealing with photons in the time domain, this formulation allows the calculation of the probability of a given photon movement. Different patterns, obtained with the new method, are compared with a Finite Element Tool ones, leading to model validation. The simulated structure included an aperture nanoantenna. With this method, the results show the light confinement and the extraordinary optical transmission phenomenon, meaning some photons on the target are refracted and re-transmitted by the metal. Thus, the output beam is more intense than the transmitted directly by the apertures.

Exploiting Extraordinary Optical Transmission in Plasmonic Slit Nanoantennas for Sensor Applications

“…Thus, not all the radiation is reflected. Moreover, if the device has dimensions of the order of these nanometres of penetration distance, then the radiation can reach another interface, enabling transmission through the metal [5], [7].…”

Nanostructures for Solar Energy Harvesting

“…An optical antenna, also called a nanoantenna, can enhance photo-physical phenomenons, for example, photodetection, where a photon gives rise to an electron and a hole, which is the underlying phenomenon responsible for the functioning of photovoltaic (PV) cells, thus nanoantennas can be used to enhance or improve the absorption of light into a given semiconductor [ 5 , 6 , 7 , 8 , 9 , 10 ].…”

“…The displacement currents flowing along the metal have smaller wavelengths than free-space due to field penetration in the metal, appearing as plasmonic effects [ 5 ]. Additionally, the electron gas within metals can couple with light in the form of a surface wave called surface plasmon polariton (SPP) [ 6 , 7 , 8 , 11 ].…”