The impact of nanoantennas on ring resonators’ performance

Self Cite

At nano-scale new phenomena have been discovered, allowing devices' miniaturisation, energy harvesting, and power reduction. The Extraordinary Optical Transmission (EOT) phenomenon was reported in 1998 by Ebessen, who stated that the resonant peaks in the response of metallic nano antennas were more intense than predicted by classical diffraction theories. Years later, the main reason for this behaviour was attributed to the Surface Plasmon Polaritons (SPP), at least in ultraviolet and visible regions. In this article, a new method to model the radiation-matter interaction on a dielectric-metal interface is proposed, based on Maxwell's equations and Fresnel Coefficients in absorbing media. Transmission percentage, angle and propagation length are obtained for a rigorous sweep on incident angle and wavelength.The results taken using some noble metals allow us to observe the presence of surface phenomena at expected SPP resonances. First, it is noticeable huge values of transmission in ultraviolet and visible regions, meaning that the metal does not reflect all the radiation. Also, the transmission angle tends to be higher, meaning huge surface components. Furthermore, the transmission length is on orders of 50-100 nm, meaning that phenomena as EOT only occurs at the nano-scale, since waves should arrive at another interface before being absorbed.

Section: A Materials Characterisationmentioning

confidence: 99%

“…is only visible at optical frequencies on nano-structures. The light-matter interaction knowledge is then the key to designing miniaturised and low-power devices [1]- [7].…”

mentioning

confidence: 99%

See 1 more Smart Citation

A New Method to Analyse the Role of Surface Plasmon Polaritons on Dielectric-Metal Interfaces

Lameirinhas¹,

Torres

Baptista³

et al. 2022

Self Cite

“…Then, for specific wavelengths and incident angles, there is some probability of a given photon being transmitted by the metal, leading to an extraordinary transmission in comparison with what is expected by classical theories (Kirchhoff's, Bethe's or Bouwkamp's theories). They assume that metals reflect all incident light, predicting a decrease proportional to (d/λ) 4 [3]- [5]. It is verified that even at large wavelengths there is a certain non-null probability to have a transmitted photon from the metal.…”

Section: B Discussionmentioning

confidence: 99%

“…In 1998, Ebbesen discovered a new optical phenomenon, named extraordinary optical transmission (EOT), which is a resonant phenomenon at a nano scale, which result from the coupling between light and surface waves, such as surface plasmon [3]. Several models, namely on frequency domain, that explain this behaviour have been developed with applications in sensor or filter design [4], [5].…”

Section: Introductionmentioning

confidence: 99%

A Novel Analysis for Light Patterns in Nano Structures

Lameirinhas¹,

Torres

Baptista³

et al. 2022

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

Lameirinhas,

Bernardo,

Torres

et al. 2024

Self Cite

In this article, a plasmonic gold nanoantenna is proposed as a sensor to monitor refractive index variations between 1.30 and 1.35. These values are defined since they are characteristic of, for instance, water-based solutions, DNA, or haemoglobin. To simulate the device a novel model is used, which takes advantage of the wave-particle dualism and the generalised Fresnel coefficients for absorbing media. Although it is a timedomain model, in this research work the model is improved to compute steady state and frequency-domain results. The response to a Dirac excitation is obtained using that novel model. The steady state is reached for a long pulse emission. The long pulse emission is emulated by a Dirac comb and consequently, the optical response of the device for this kind of excitation is obtained considering the sum of several Dirac's responses shifted in time. Then, steady state might be reached as suggested by the presented results. Taking into account the obtained pulse responses, the refractive index sensor for the range 1.30-1.35 is proposed. The obtained results suggest that 350 nm and 450 nm are the best wavelengths to detect these analyte variations. The sensitivity reaches values up to around 110%/RIU, but sensitivities around 80%/RIU are computed within the range 250-500 nm.