arXiv subjects

Riad Haidar

Publications and source records attributed to Riad Haidar.

3 recordsLinked to original sources

arXiv2021

Hybrid modes in a single thermally excited asymmetric dimer antenna

The study of hybrid modes in a single dimer of neighboring antennas is an essential step to optimize the far-field electromagnetic (EM) response of large-scale metasurfaces or any complex antenna structure made up of subwavelength building blocks. Here we present far-field infrared spatial modulation spectroscopy (IR-SMS) measurements of a single thermally excited asymmetric dimer of square metal-insulator-metal (MIM) antennas separated by a nanometric gap. Through thermal fluctuations, all the EM modes of the antennas are excited and hybrid bonding and antibonding modes can be observed simultaneously. We study the latter within a plasmon hybridization model, and analyse their effect on the far-field response.

physics.optics↗

arXiv2020

Dark-modes excitation in coupled nano Fabry-Perot structure induced by symmetry breaking

Absorbing metamaterials have attracted a widespread interest but suffer from the metallic ohmic losses that limits their Q-factor to values around 10. In this paper, we report the engineering and experimental characterization of a high Q dark-mode in a metasurface resulting from the coupling of several individual nano-Fabry-Perot structures supporting low-contrast resonances. The resulting resonance has a Q-factor above 20 and a nearly total absorption. Moreover, we also demonstrate that several dark-mode resonances can be excited simultaneously, by exploiting the coupling of various pairs of nano Fabry-Perot resonators within the same subwavelength period. Finally, the resonance's Q-factor depends monotonously on the thickness of the metasurface and can reach values up to 85.

physics.optics↗

arXiv2014

Giant field enhancement by funneling effect into sub-wavelength slit-box resonators

Inspired by the acoustic Helmholtz resonator, we propose a slit-box electromagnetic nanoantenna able to concentrate the energy of an incident beam into surfaces a thousand times smaller than with a classical lens. This design gives birth to giant field intensity enhancement in hot volume, throughout the slit. It reaches $10^4$ in the visible up to $10^8$ in the THz range even with focused beams thanks to an omnidirectional reception. These properties could target applications requiring extreme light concentration, such as SEIRA, non-linear optics and biophotonics.

physics.optics↗