Publications associées à Divergence de faisceau

Photothermal spectroscopy on-chip sensor for the measurement of a PMMA film using a silicon nitride micro-ring resonator and an external cavity quantum cascade laser

Laser-based mid-infrared (mid-IR) photothermal spectroscopy (PTS) represents a selective, fast, and sensitive analytical technique. Recent developments in laser design permits the coverage of wider spectral regions in combination with higher power, enablin ...

Walter De Gruyter Gmbh2024

Mode-Specific Coupling of Nanoparticle-on-Mirror Cavities with Cylindrical Vector Beams

Christophe Marcel Georges Galland, Valeria Vento, Sachin Suresh Verlekar, Philippe Andreas Rölli

Nanocavities formed by ultrathin metallic gaps permitthe reproducibleengineering and enhancement of light-matter interaction, withmode volumes reaching the smallest values allowed by quantum mechanics.While the enhanced vacuum field in metallic nanogaps ha ...

2023

Transfer learning application of self-supervised learning in ARPES

Gabriel Aeppli

There is a growing recognition that electronic band structure is a local property of materials and devices, and there is steep growth in capabilities to collect the relevant data. New photon sources, from small-laboratory-based lasers to free electron lase ...

IOP Publishing Ltd2023

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, Hao Song, Xinzhou Su

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

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, Hao Song, Xinzhou Su

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

Study of Negative Ion Beamlets Produced in SPIDER by Beam Emission Spectroscopy

Riccardo Agnello

Among the beam diagnostics routinely employed in source for production of ion of deuterium (SPIDER), beam emission spectroscopy (BES) provides valuable information for beam characterization, thus driving source optimization methods. In particular, this tec ...

2022

Structured light engineering using a photonic nanojet

Toralf Scharf, Maryam Yousefi, Daniel Necesal

In this Letter, we present the photonic nanojet as a phenomenon in a structured light generator system that is implemented to modify the source focal spot size and emission angle. The optical system comprises a microlens array that is illuminated by a focu ...

OPTICAL SOC AMER2021

Laser treatment systems and methods for in-situ laser shock peening (lsp) treatment of parts during production thereof by a selective laser sintering or melting (sls/slm) process, and additive manufacturing systems and methods implementing the same

Roland Logé, Nikola Kalentics

There is described, in accordance with a first aspect of the invention, a laser treatment system and method for, in particular, imparting beneficial residual stresses into a desired part (P) during production thereof by a Selective Laser Sintering or Melti ...

2021

Rapid melting and revitrification as an approach to microsecond time-resolved cryo-electron microscopy

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss, Oliver Florian Harder

Proteins typically undergo dynamics on the microsecond to millisecond timescale, which is much faster than the time resolution of cryo-electron microscopy. Here, we propose a novel approach for microsecond time-resolved cryo-electron microscopy that involv ...

Elsevier2021

Structured light generation by refractive-diffractive micro optical array illuminators

Maryam Yousefi

Structured light generation having broad applications in different optical fields, is the topic of this thesis. Our structured light generation strategy is based on applying periodic microoptical elements at the refraction-diffraction limit, under a focuse ...

EPFL2021

Design and Thermal-Structural Analyses of Ancillary Components for the Optical Steering Mirror (M4) for the ITER ECH Upper Launcher

Timothy Goodman, René Chavan, Matteo Vagnoni, Avelino Mas Sanchez

Each of the four ITER Electron Cyclotron Heating Upper Launcher (ECHUL) features eight transmission lines (TLs) that are used to inject 170-GHz microwave power into the plasma at a level of up to 1.31 MW (at the TL diamond window) per line. The millimeter ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2020

Beam duct for the 1 MW neutral beam injector on TCV

Basil Duval, Stefano Coda, Yves Martin, Alexander Karpushov, Matthieu Toussaint, Frédéric Dolizy, Roberto Maurizio

The 1MW power of the neutral beam injector (NBI) enters the plasma of the Tokamak a Configuration Variable (TCV) through a duct. The original beam propagation model predicted a maximal heat flux on the internal faces of the duct below 350 kW/m(2), leading ...

2020

Update of ion-optical system of neutral beam of Tokamak a Configuration Variable

Alexander Karpushov

An injector of fast deuterium atoms for plasma heating was designed and installed at the Tokamak a Configuration Variable (TCV). The neutral beam can deliver 1 MW power to the plasma in 2 s pulses. An ion beam of the injector is formed by a triode multisli ...

AMER INST PHYSICS2020

Elastic properties of self-organized nanogratings produced by femtosecond laser exposure of fused silica

Yves Bellouard, Pieter Vlugter

Under certain exposure conditions, a femtosecond laser beam focused in the bulk of fused silica leads to the formation of self-organized structures consisting of a series of “nanolayers,” parallel to one another. Remarkably, this laser-induced nanoscale an ...

2020

Nanosecond pulsed laser-processing of CVD diamond

Patrik Willi Hoffmann, Marco Cantoni, Sébastien Equis

This work considers the resulting material structural effects of laser-processing chemical vapor deposited (CVD) diamond. The utilized 532 nm wavelength laser had a pulse duration of 40 ns together with a spot diameter of ca. 40 mu m. The effect of cutting ...

ELSEVIER SCI LTD2020

Dot pattern generation using thick sinusoidal phase grating under Gaussian beam illumination

Toralf Scharf, Maryam Yousefi

Far-field dot pattern generation is analyzed for a Gaussian beam source that illuminates a sinusoidal phase grating which is placed at a certain distance behind the beam waist. We obtain a bigger field of view with more numbers of points using a Gaussian b ...

SPIE-INT SOC OPTICAL ENGINEERING2019

A Compact Laser-Steering End-Effector for Transoral Robotic Surgery

Laryngeal cancer treatments, while curative, often lead to voice impairment. Minimally invasive surgical methods that facilitate greater preservation of healthy tissue have recently emerged, but they are still limited in important ways. In this work, we de ...

IEEE2019

Resonant Waveguide Gratings for Color-Selective Diffraction

Giorgio Quaranta

Resonant waveguide gratings (RWGs), also known as guided mode resonant (GMR) gratings or waveguide-mode resonant gratings, are dielectric structures where these resonant diffractive elements benefit from lateral leaky guided modes and can operate from UV t ...

EPFL2019

Multi-slit triode ion optical system with ballistic beam focusing

Alexander Karpushov, Anton Smirnov

Multi-slit triode ion-optical systems with spherical electrodes are of interest for formation of intense focused neutral beams for plasma heating. At present, two versions of focusing multi-slit triode ion optical system are developed. The first ion optica ...

Amer Inst Physics2016

Spatial multistability induced by cross interactions of confined polariton modes

Benoît Marie Joseph Deveaud, Daniel Oberli, François Morier-Genoud, Marcia Portella Oberli, Claudéric Ouellet-Plamondon, Grégory Chilpéric Sallen

We demonstrate the occurrence of spatial multistability using laterally confined microcavity exciton-polaritons. By coherently exciting with a blue detuned laser a series of confined polariton modes, we investigate the effects of multistability on the tran ...

Amer Physical Soc2016