Publications by Karim Achouri | EPFL Graph Search

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We present a frequency-domain modeling technique for second-order nonlinear metasurfaces. The technique is derived from the generalized sheet transition conditions (GSTCs), which have been so far mostly used for modeling linear metasurfaces. In this work, ...

This paper theoretically proposes a multichannel nonlocal metasurface computer characterized by generalized sheet transition conditions (GSTCs) and surface susceptibility tensors. The study explores polarization- and angle-multiplexed metasurfaces enabling ...

We study the angular scattering behavior of bianisotropic metasurfaces and deduce relationships between the corresponding symmetrical angular scattering properties and the structural symmetries of their scattering particles. This may be of practical intere ...

Metasurfaces are efficient and versatile electromagnetic structures that have already enabled the implementation of a wide range of microwave and photonic wave shaping applications. Despite the extensive research into metasurfaces, a rigorous and comprehen ...

Resonant optical response is one of the key effects in nanophotonic structures. The characterization of the fundamental resonance metrics, quality factor, electric or magnetic field localization, polarization, and chirality, is often built on a multipolar ...

It has been observed that achiral nanoparticles, such as flat helices, may be subjected to an optical torque even when illuminated by normally incident linearly polarized light. However, the origin of this fascinating phenomenon has so far remained mostly ...

We present our recent progress pertaining to the synthesis and analysis of bianisotropic linear and nonlinear metasurfaces. These developments are based on the generalized sheet transition conditions (GSTCs), which provide a very complete and general metho ...

We analyze the superposition of Cartesian multipoles to reveal the mechanisms underlying the origin of optical forces. We show that a multipolar decomposition approach significantly simplifies the analysis of this problem and leads to a very intuitive expl ...

The design of wavefront-shaping devices is conventionally approached using real-frequency modeling. However, since these devices interact with light through radiative channels, they are by default non-Hermitian objects having complex eigenvalues (poles and ...

We demonstrate a nonlinear plasmonic metasurface that exhibits strongly asymmetric second-harmonic generation: nonlinear scattering is efficient upon excitation in one direction, and it is substantially suppressed when the excitation direction is reversed, ...

In this article, we investigate the possibility to model a metasurface, defined as a zero-thickness sheet of surface polarization currents and described by generalized sheet transition conditions (GSTCs), by a thin slab with a subwavelength thickness and u ...

There is today a growing need to accurately model the angular scattering response of metasurfaces for optical analog processing applications. However, the current metasurface modeling techniques are not well suited for such a task since they are limited to ...

We propose a surface-wave dispersion retrieval method and synthesis technique that applies to bianisotropic metasurfaces that are embedded in symmetric or asymmetric environments. Specifically, we use general zero-thickness sheet transition conditions to r ...

Analog computing has emerged as a promising candidate for real-time and parallel continuous data processing. This paper presents a reciprocal way for realizing asymmetric optical transfer functions (OTFs) in the reflection side of the on-axis processing ch ...

We present an initial study of the angular spectrum of a bianisotropic refractive metasurface at an interface between two dielectric media. In this study, we report on the existence of three distinct angular regions: a) a rotated transmission cone, b) a mo ...

We present a nonlinear metasurface modelling frame- work based on the generalized sheet transition conditions (GSTC). It may be used to synthesize or analyse the scat- tering behavior of second- and third-order metasurfaces. We specifically study second-ha ...

Being able to understand how optical forces emerge from the interaction of light with matter is paramount for controlling the motion of nanoparticles as well as powering nanomotors. The purpose of this work is to uncover the physical mechanisms at the orig ...

We demonstrate the possibility of achieving an optical pulling force without complex beam-shaping techniques. By using optical pulses detuned from the resonant frequency of the structure, we create conditions in which the spectral maxima of the excited cur ...

Karim Achouri

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Modeling of second-order nonlinear metasurfaces

Generalized Optical Signal Processing Based on Multioperator Metasurfaces Synthesized by Susceptibility Tensors

Symmetries and Angular Scattering Properties of Metasurfaces

Angle-invariant scattering in metasurfaces

Optimal Poloidal Multipole Expansion Centres

Multipolar Pseudochirality-Induced Optical Torque

Synthesis and Analysis of Linear and Nonlinear Bianisotropic Metasurfaces

Multipole interplay controls optical forces and ultra-directional scattering

Asymmetric phase modulation of light with parity-symmetry broken metasurfaces

Demonstration of a Plasmonic Nonlinear Pseudodiode

Limitations of the Metasurface Diluted-Slab Model

Multipolar Modeling of Spatially Dispersive Metasurfaces

Surface-wave dispersion retrieval method and synthesis technique for bianisotropic metasurfaces

Reciprocal Metasurfaces for On-axis Reflective Optical Computing

Study of the Angular Spectrum of a Bianisotropic Refractive Metasurface at a Dielectric Interface

Modelling of nonlinear metasurfaces: Second-harmonic generation and Kerr effect

Explanation of Optical Force and Torque on Nanomotors as the Interplay of Huygens Sources

Designing the magnetic second harmonic emission from plasmonic nanostructures

Pulling force enabled by unlocking the optical phase

Tailoring upconversion luminescence with multi-resonant antennas