We investigate a fundamental limitation occurring in vacuum ultraviolet and extreme ultraviolet seeded free electron lasers (FELs). For a given electron beam and undulator configuration, an increase of the FEL output energy at saturation can be obtained via an increase of the seed pulse duration. We put in evidence a complex spatiotemporal deformation of the amplified pulse, leading ultimately to a pulse splitting effect. Numerical studies of the Colson–Bonifacio FEL equations reveal that slippage length and seed laser pulse wings are core ingredients of the dynamics.
Influence of air-filling fraction on forward Raman-like scattering by
transversely trapped acoustic resonances in photonic crystal fibers
A. Brenn,
G. S. Wiederhecker,
M. S. Kang,
H. Hundertmark,
N. Joly,
P. St. J. Russell
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS
26
(8)
1641-1648
(2009)
Raman-like forward scattering by acoustic phonons transversely trapped in birefringent silica-air photonic crystal fibers is studied. As the air-filling fraction increases, core-confined acoustic resonances become increasingly apparent at higher frequencies (> 1.1 GHz), while the number of cladding-confined acoustic modes involved in scattering falls. Two main types of scattering are observed: intramodal (scattering to new frequencies within the same optical mode) and intermodal (frequency-shifted scattering to a different optical mode). It is shown that the twofold symmetric microstructure in a birefringent fiber causes strongly polarization-dependent intramodal scattering. Good agreement is obtained between the experimental measurements and numerical solutions of both the acoustic and electromagnetic wave equations by using a full-vectorial finite-element approach. Phononic bandgaps are found to play a significant role at higher air-filling fractions, leading to the appearance of additional bands in the scattering spectrum. (C) 2009 Optical Society of America
Scientific career
Since 2021: Head of the microstructured optical fibres independent research group at the Max-Planck Institute for the Science of Light in Erlangen, Germany
Since 2009: Associate professor at the Univ. of Erlangen-Nuremberg in Germany
2005 – 2008: Maître de conférences at the Univ. of Lille in France
Education background
2012: Habilitation at the Ecole Normale Supérieure of Cachan (France) Title: Supercontinuum generation using pulses propagating in photonic crystal fibres, Defended in July. 10th 2012. Thesis adviser: Prof. Dr. Joseph Zyss.
2002-2005: Post-doctoral fellow at the University of Bath (UK) in the group of Prof. Philip Russell
1999-2002: PhD with honors (“Félicitations du jury”) at the laboratory of Physics of Lasers, Atoms, and Molecules (PhLAM) at the University of Lille (France) Title: Instabilities in pulsed mode-locked lasers: techniques for observation and control Defended on Sept. 23rd 2002. Thesis adviser: Prof. Dr. Serge Bielawski.
Awards & appointments
Since 2023: Advisor of the Erlangen Optica Student Chapter
Since 2021: Scientific coordinator of the Internation Max Planck School for the Physics of Light (IMPRS-PL)
Since 2020: Senior member of Optical Society of America (OSA)
Since 2019: Fellow of the Max Planck School of Photonics (MPSP) and member of the selection committee
Since 2016: Fellow of the Max Planck Center for Extreme and Quantum Photonics, Ottawa, Canada
1999: MENRT scholarship from the French ministry of Research to perform his doctoral degree at the University of Lille from 1999 to 2002
1998: Awarded a CIME scholarship from AUF (Agence universitaire de la Francophonie) to perform his Master study at Laval University (Québec) in 1998
Professional activities
2024: Member of the Technical Program Committee for the SPIE Photonics Europe in Strasbourg
Since 2022: Associate Editor of Opt. Express
2017: General chair of the 1st Sino-German symposium on fiber photonics for light-matter interaction in Shanghai, China
2017 – 2018: Member of the Technical Program Committee for SPIE UV and higher energy photonic
2013 – 2017: Member of Technical Program Committee for CLEO US (OSA)
2015: co-Chair of the 2nd Siegman International School of Laser (OSA)
Since 2015: Member of the Technical Program Committee for WSOF (OSA) in Hong-Kong (2015), Limasol in Cypris (2017), Adelaide in Australia (2022), and in Prague in Czech Republic (2025)
Since 20214: Member of the Student Commission of the internation Master of Advanced Optics and Technologies (MAOT)
2013: Topical session at PIERS (Progress in Electromagnetics Research Symposium) in Stockholm
2011: International conference on Nonlinear optics and complexity in photonic crystal fibers and nanostructures in Erice, in Sicily
2011: 14th International SAOT workshop on Fiber laser, sensors and materials at Reicheschwand, Germany
Since 2009: External expert for the evaluation of proposals from ANR (National agency of research in France), the Polish Society of Science, DFG (National agency of research in Germany) and ERC (European Research Council)
Since 2009: Supervisor of 13 PhD students, 2 post-docs, 14 MSc students
Ongoing projects
DFG project JO 1090/8-3 – OrbitFlySens [FAU] Orbiting flying particle sensor (with Bernhard Schmauß, FAU) – 2025-2028
BayFrance FK-34-2024 [FAU] Real-time detection of Terahertz signals using ultrashort lasers Mobility allowance – collaboration with University of Lille - 2025
BayFrance FK-35-2024 [FAU] Exploring chiral fibers for new-type of polarization-resolved endoscopy Mobility allowance – collaboration with University of Marseille – 2025
DFG project JO 1090/3-2 – Photon Triplets [FAU] Generation of photon triplets via three-photon parametric down-conversion (with Maria Chekhova) – 2024-2027
QuNet beta [MPL] 2021-2026
Max-Planck-School of Photonics (MPSP) [FAU] 2019-2025
DFG project JO 1090/6-1 -Twin Beams [FAU] Fiber source of entangled photons with giant tunable frequency separation (with Maria Chekhova) - 2021-2024
DFG project JO 1090/4-1 – Rydbergatoms in photonic crystal fibres [FAU] (with Robert Löw, University of Stuttgart) - 2019-2023
BayFrance FK-29-2018 [FAU] Frequency conversion of single-photon quantum sources using gas-filled hollow-core photonic crystal fibres Mobility allowance – collaboration with LKB, Ens Paris, France - 2018
DFG project JO 1090/3-1 – Photon Triplets [FAU] Generation of photon triplets via three-photon parametric down-conversion (with Maria Chekhova) – 2017-2020
BayFrance FK-38-2013 [FAU] Dynamical instabilities in photonic crystal fiber ring cavities synchronously pumped by femtosecond pulses Mobility allowance – collaboration with University of Lille, France - 2013-2014
