Publication

A nonlinear, non-reciprocal (?) metasurface

2024

Abstract

We demonstrate experimentally a metasurface built from Ag and Al meta-atoms, which exhibits a very peculiar nonlinear response: upon illumination from one side, it produces a very strong second harmonic response, while this is not at all the case for illumination from the other side. I will discuss the underlying mechanisms that lead to this effect, especially the role of bi-anisotropy both at the fundamental and second harmonic frequencies. The linear and non-linear susceptibilities of the system can be retrieved from numerical simulations. I will also discuss whether this device is reciprocal or not.

Official source

https://infoscience.epfl.ch/entities/publication/69d5ed0b-15cd-46d3-afbd-a7c5c0cb40d3

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2024

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/69d5ed0b-15cd-46d3-afbd-a7c5c0cb40d3

About this result

Related concepts (32)

Fundamental frequency

The fundamental frequency, often referred to simply as the fundamental, is defined as the lowest frequency of a periodic waveform. In music, the fundamental is the musical pitch of a note that is perceived as the lowest partial present. In terms of a superposition of sinusoids, the fundamental frequency is the lowest frequency sinusoidal in the sum of harmonically related frequencies, or the frequency of the difference between adjacent frequencies. In some contexts, the fundamental is usually abbreviated as 0, indicating the lowest frequency counting from zero.

Nonlinear optics

Nonlinear optics (NLO) is the branch of optics that describes the behaviour of light in nonlinear media, that is, media in which the polarization density P responds non-linearly to the electric field E of the light. The non-linearity is typically observed only at very high light intensities (when the electric field of the light is >108 V/m and thus comparable to the atomic electric field of ~1011 V/m) such as those provided by lasers. Above the Schwinger limit, the vacuum itself is expected to become nonlinear.

High harmonic generation

High harmonic generation (HHG) is a non-linear process during which a target (gas, plasma, solid or liquid sample) is illuminated by an intense laser pulse. Under such conditions, the sample will emit the high harmonics of the generation beam (above the fifth harmonic). Due to the coherent nature of the process, high harmonics generation is a prerequisite of attosecond physics. Perturbative harmonic generation is a process whereby laser light of frequency ω and photon energy ħω can be used to generate new frequencies of light.

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A nonlinear, non-reciprocal (?) metasurface

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