Publications associées à Demonstration of efficient spin injection in a CW VECSEL at RT and dynamic control of its polarization state

Domain Imaging and Switching Dynamics in BaTiO3-Based Photonic Integrated Devices

Keeping up with our constantly connected lifestyle of instant messages and video streaming has its repercussions. Data centers have been gobbling up resources becoming a significant share of the energy used worldwide. To keep up with demand and curb the en ...

EPFL2023

Collective behavior and emerging patterns in dense dry aligning active matter

Elena Sesé Sansa

In this thesis, we study systems of active particles interacting via generic torques of different nature. We analyze the phase behavior of these systems, which results from the interplay between self-propulsion, excluded-volume and torques. We tackle the p ...

EPFL2022

Smooth GaN membranes by polarization-assisted electrochemical etching

Jean-François Carlin, Nicolas Grandjean, Joachim Armand Simonne Ciers

III-nitride membranes offer promising perspectives and improved device designs in photonics, electronics, and optomechanics. However, the removal of the growth substrate often leads to a rough membrane surface, which increases scattering losses in optical ...

AMER INST PHYSICS2021

Liouvillian spectral collapse in the Scully-Lamb laser model

Fabrizio Minganti

Phase transitions of thermal systems and the laser threshold were first connected more than forty years ago. Despite the nonequilibrium nature of the laser, the Landau theory of thermal phase transitions, applied directly to the Scully-Lamb laser model (SL ...

AMER PHYSICAL SOC2021

Fundamentals and perspectives of ultrafast photoferroic recording

Anna Pogrebna

The ability to switch ferroics (ferro-, ferri-, antiferromagnets, ferroelectrics, multiferroics) between two stable bit states is one of the keystones of modern data storage technology. Due to many new ideas, originating from fundamental research during th ...

2020

Field-induced reorientation of helimagnetic order in Cu2OSeO3 probed by magnetic force microscopy

Helmuth Berger

Cu2OSeO3 is an insulating skyrmion-host material with a magnetoelectric coupling giving rise to an electric polarization with a characteristic dependence on the magnetic-field (H) over right arrow. We report a magnetic force microscopy imaging of the helic ...

AMER PHYSICAL SOC2020

Fast and ultrafast electron microscopies for skyrmions and plasmonics

Gabriele Berruto

In recent years, topology gained a central role in physics. We learnt that energetics could be often explained better by classes of objects defined by having qualitative differences. In today's jargon, we say they are topologically distinct. The process of ...

EPFL2019

Tunable polarization converter based on one-dimensional graphene metasurfaces

Babak Rahmani

We introduce a new metasurface structure for controlling the polarization of light by leveraging a well-harmonized combination of graphene and dielectric. The proposed metasurface is composed of an array of rectangular pillars laterally sandwiched by ribbo ...

OPTICAL SOC AMER2018

Thermodynamic evidence of a second skyrmion lattice phase and tilted conical phase in Cu2OSeO3

Helmuth Berger

Precision measurements of the magnetization and ac susceptibility of Cu2OSeO3 are reported for magnetic fields along different crystallographic directions, focusing on the border between the conical and the field-polarized state for a magnetic field along ...

2018

Near optimal graphene terahertz non-reciprocal isolator

Juan Ramon Mosig, Julien Perruisseau-Carrier, Mihai Adrian Ionescu, Clara-Fausta Moldovan, Michele Tamagnone

Isolators, or optical diodes, are devices enabling unidirectional light propagation by using non-reciprocal optical materials, namely materials able to break Lorentz reciprocity. The realization of isolators at terahertz frequencies is a very important ope ...

Nature Publishing Group2016

Method and apparatus for measuring the local birefingence along an optical waveguide

Luc Thévenaz, Marcelo Alfonso Soto Hernandez, Xin Lu

This invention relates to a system and method to determine the distributed birefringence profile along an optical fibre. Birefringence manifests as different refractive indices for two orthogonal states of polarization of the light propagating in the optic ...

2016

Effective-surface-energy approach for size effects in ferroics

Nava Setter, Alexander Tagantsev, Jin Wang

We present a simple approach enabling analytical treatments of size effects in ferroelectric samples of complicated shapes for the cases where long-range depolarizing effects are not involved. The key element of the approach is the presentation of the ener ...

American Physical Society2015

Optical properties of waveguide-coupled nanowires for sub-wavelength detection in microspectrometer applications

Alessandro Crespi, Toralf Scharf

In this paper we experimentally investigate optical interactions between gold nanowires and fs-laser written waveguides in a view of applications for stationary-wave integrated Fourier-transform spectrometers in a movable mirror configuration. For this pur ...

European Optical Society2015

Optical Injection and Lasing Dynamics in Long-Wavelength VCSELs With Intracavity Patterning

Benjamin Dwir, Elyahou Kapon, Alexei Sirbu, Vladimir Iakovlev, Alexandru Mereuta, Andrei Caliman, Zlatko Mickovic, Christopher Michael Long, Dalila Ellafi

We present the static and optical injection response of wafer-fused long-wavelength VCSELs with and without intracavity patterning. It is found that the extra optical cavity patterning increases the gain anisotropy between orthogonal polarization modes, in ...

Ieee-Inst Electrical Electronics Engineers Inc2015

Pressure effect on magnetism and multiferroicity in Mn2GeO4

Jonathan White

The effect of high pressure exceeding 6 GPa on magnetism and multiferroicity was investigated for the olivine Mn2GeO4 that shows successive magnetic transitions at ambient pressure and a ferroelectric ground state driven by spin- spiral order. We measured ...

Amer Physical Soc2014

Spin dynamics and magnetoelectric properties of the coupled-spin tetrahedral compound Cu2Te2O5Cl2

Helmuth Berger

We report on the spin dynamics and discovery of magnetoelectricity in the coupled-spin tetrahedral compound Cu2Te2O5Cl2. Te-125 NMR measurements show an anomalous resonance frequency shift and a signal wipe-out phenomenon around the Neel temperature T-N = ...

Amer Physical Soc2014

Optical properties of BiTeBr and BiTeCl

Helmuth Berger, Philippe Bugnon, Arnaud Magrez, Ana Akrap, Dirk Van der Marel

We present a comparative study of the optical properties-reflectance, transmission, and optical conductivity- and Raman spectra of two layered bismuth-tellurohalides BiTeBr and BiTeCl at 300 and 5 K, for light polarized in the a-b planes. Despite different ...

Amer Physical Soc2014

Analysis and Control of Optical Modes in VCSELs and VCSEL-Arrays

Elodie Lamothe

In this thesis, we studied the modal structure and the polarization of the optical field emitted by vertical-cavity surface-emitting lasers (VCSELs) emitting in the short- and long-wavelength domains (0.9-1.3μm). Our study concerns two types of components: ...

EPFL2013

A Simple Reflectarray Cell with 1-bit Phase Control and Polarization Flexibility

Julien Perruisseau-Carrier, Tomislav Debogovic

In this work we present a simple reconfigurable reflectarray (RRA) unit cell general topology and implementation, which allows the independent control of the phase and polarization of the reflected electromagnetic wave. The 1-bit phase control (with 180 de ...

Ieee2013

Multiferroicity in the geometrically frustrated FeTe2O5Cl

Helmuth Berger

The layered FeTe2O5Cl compound was studied by specific-heat, muon-spin relaxation, nuclear magnetic resonance, and dielectric as well as neutron and synchrotron x-ray diffraction measurements, and the results were compared to isostructural FeTe2O5Br. We fi ...

Amer Physical Soc2013