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Concept

Orbital angular momentum multiplexing

Publications associées (29)

Single-shot Kramers-Kronig complex orbital angular momentum spectrum retrieval

Camille Sophie Brès, Jianqi Hu

Orbital angular momentum (OAM) spectrum diagnosis is a fundamental building block for diverse OAM-based systems. Among others, the simple on-axis interferometric measurement can retrieve the amplitude and phase information of complex OAM spectra in a few s ...

SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS2023

Topological MIMO Optical Signal Processing

Romain Christophe Rémy Fleury, Farzad Zangeneh Nejad

An important advantage of optical signal processing is the possibility of performing various operations in parallel. Among the techniques proposed for parallel optical signal processing, frequency division multiplexing (FDM) is a well-known approach, in wh ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2023

Hierarchy of quasisymmetries and degeneracies in the CoSi family of chiral crystal materials

Philip Johannes Walter Moll, Yi-Chiang Sun, Chunyu Guo

In materials, certain approximated symmetry operations can exist in a lower-order approximation of the effective model but are good enough to influence the physical responses of the system, and these approximated symmetries were recently dubbed "quasisymme ...

AMER PHYSICAL SOC2023

Generation of OAM-carrying space-time wave packets with time-dependent beam radii using a coherent combination of multiple LG modes on multiple frequencies

Tobias Kippenberg, Maxim Karpov, Zhe Zhao

Space-time (ST) wave packets, in which spatial and temporal characteristics are coupled, have gained attention due to their unique propagation characteristics, such as propagation invariance and tunable group velocity in addition to their potential ability ...

Optica Publishing Group2022

Hard X-ray helical dichroism of disordered molecular media

Majed Chergui, Giulia Fulvia Mancini, Malte Oppermann, Oliviero Cannelli, Dominik Kinschel, Camila Bacellar Cases Da Silveira

Chirality is a structural property of molecules lacking mirror symmetry that has strong implications in diverse fields, ranging from life sciences to materials science. Chirality-sensitive spectroscopic methods, such as circular dichroism, exhibit weak sig ...

Nature Publishing Group2022

Active Ferromagnetic Metasurface with Topologically Protected Spin Texture for Spectral Filters

Dirk Grundler, Haiming Yu

Electromagnetic metasurfaces modulate a material's response to electromagnetic waves by specifically arranged elements with dimensions below the wavelength. They have opened new fields of research, including flat optics and nanophotonics on a chip. Ferroma ...

2022

Experimental demonstration of dynamic spatiotemporal structured beams that simultaneously exhibit two orbital angular momenta by combining multiple frequency lines, each carrying multiple Laguerre-Gaussian modes

Tobias Kippenberg, Maxim Karpov, Zhe Zhao

In general, there are different, relatively independent forms of orbital angular momenta at a given propagation distance, which might exhibit different dynamic spatial characteristics. One type involves a beam with a helical phase-front that rotates around ...

Optica Publishing Group2022

Spectral self-imaging of optical orbital angular momentum modes

Camille Sophie Brès, Jianqi Hu

The Talbot self-imaging effect is mostly present in the forms of space or time, or in the frequency domain by the Fourier duality. Here, we disclose a new spectral Talbot effect arising in optical orbital angular momentum (OAM) modes. The effect occurs in ...

AIP Publishing2021

Versatile shaping of optical frequency combs and applications

Jianqi Hu

Optical frequency combs are a series of phase-locked and equidistant laser lines in the spectral domain. In the time domain, they correspond to periodic pulse trains by the Fourier relation. The ability to shape optical combs and pulse trains is pivotal to ...

EPFL2021

Quasi-Global Momentum: Accelerating Decentralized Deep Learning on Heterogeneous Data

Martin Jaggi, Sebastian Urban Stich, Tao Lin, Sai Praneeth Reddy Karimireddy

Decentralized training of deep learning models is a key element for enabling data privacy and on-device learning over networks. In realistic learning scenarios, the presence of heterogeneity across different clients' local datasets poses an optimization ch ...

JMLR-JOURNAL MACHINE LEARNING RESEARCH2021

Spatial wave control using a self-biased nonlinear metasurface at microwave frequencies

Ali Momeni

Recently, investigation of metasurfaces has been extended to wave control through exploiting nonlinearity. Among all of the ways to achieve tunable metasurfaces with multiplexed performances, nonlinearity is one of the promising choices. Although several p ...

2020

Parallel Optical Spatial Signal Processing Based on 2x2 MIMO Computational Metasurface

Romain Christophe Rémy Fleury, Ali Momeni

We introduce a novel concept of Multi-Input Multi-Output (MIMO) metasurface processor with asymmetric Optical Transfer Function (OTF) which can perform spatial first-order derivation on two orthogonal distinct input signals for both TM and TE polarizations ...

IEEE2020

Optical Characterization of an Intra-Arterial Light and Drug Delivery System for Photodynamic Therapy of Atherosclerotic Plaque

Hubert van den Bergh, Georges Wagnières, Matthieu Philippe Emmanuel Zellweger, Andreas Pitzschke, Ying Xiao

Although the versatility of photodynamic therapy (PDT) is well established, the technical aspects of light delivery systems vary significantly depending on the targeted organ. This article describes the optical properties of a light and drug delivery syste ...

2020

On design strategies for binary dielectric metasurfaces based on the Fourier modal method

Kévin Müller

Binary dielectric metasurfaces are arrays of sub-wavelength structures that act as a thin layer of artificial material. They are generally lossless and relatively simple to fabricate since only a single structuring step is required. By carefully designing ...

EPFL2020

Momentum space CFT correlators for Hamiltonian truncation

Matthew Thomas Walters

We consider Lorentzian CFT Wightman functions in momentum space. In particular, we derive a set of reference formulas for computing two- and three-point functions, restricting our attention to three-point functions where the middle operator (corresponding ...

Springer Nature2020

Doubly resonant second-harmonic generation of a vortex beam from a bound state in the continuum

Nicolas Grandjean, Romuald Houdré, Jean-François Carlin, Matteo Galli, Momchil Minkov, Marco Clementi, Jun Wang

Second-harmonic generation in nonlinear materials can be greatly enhanced by realizing doubly resonant cavities with high quality factors. However, fulfilling such doubly resonant condition in photonic crystal (PhC) slab cavities is a long-standing challen ...

2020

Insights into image contrast from dislocations in ADF-STEM

Cécile Hébert, Emad Oveisi, Maria Chiara Spadaro

Competitive mechanisms contribute to image contrast from dislocations in annular dark-field scanning transmission electron microscopy (ADF-STEM). A clear theoretical understanding of the mechanisms underlying the ADF-STEM contrast is therefore essential fo ...

ELSEVIER SCIENCE BV2019

Probing Molecular Chirality by Orbital-Angular-Momentum-Carrying X-ray Pulses

Jérémy Raymond Jean Maurice Rouxel

A twisted X-ray beam with orbital angular momentum is employed in a theoretical study to probe molecular chirality. A nonlocal response description of the matter-field coupling is adopted to account for the field short wavelength and the structured spatial ...

AMER CHEMICAL SOC2019

Self-imaging of Azimuthal Intensity Petal Based on Orbital Angular Momentum Beams

Camille Sophie Brès, Jianqi Hu

We demonstrate for the first time azimuthal Talbot effect based on orbital angular momentum beams. The intensity petal is self-imaged in the azimuthal angle. We also draw the analogy between azimuthal and temporal Talbot effect. ...

2018

Generation of acoustic helical wavefronts using metasurfaces

Juan Ramon Mosig, Hervé Lissek, Seyyed Hussein Seyyed Esfahlani

It has been shown that acoustic waves with helical wavefronts can carry angular momentum, which can be transmitted towards a propagating medium. Such a wave field can be achieved by using a planar array of electroacoustic transducers, forming a given spati ...

2017