A new asymptotic analysis of the equations for a mode-locked laser exhibiting a Q-switching instability is proposed. We determine the Hopf bifurcation point responsible for this instability and discuss its behavior in terms of the laser parameters. Our analysis is valid for all class B lasers exhibiting slowly damped relaxation oscillations which include solid state and semiconductor lasers. In the limit of weak nonlinearities, we recover Haus stability conditions. In the case of strongly nonlinear losses, as for the usual picosecond and femtosecond laser devices, we determine the stability conditions.
Polarization modulation instability in photonic crystal fibers
R. J. Kruhlak,
G. K. Wong,
J. S. Chen,
S. G. Murdoch,
R. Leonhardt,
J. D. Harvey,
N. Y. Joly,
J. C. Knight
Polarization modulation instability (PMI) in birefringent photonic crystal fibers has been observed in the normal dispersion regime with a frequency shift of 64 THz between the generated frequencies and the pump frequency. The generated sidebands are orthogonally polarized to the pump. From the observed PMI frequency shift and the measured dispersion, we determined the phase birefringence to be 5.3×10−5 at a pump wavelength of 647.1 nm. This birefringence was used to estimate the PMI gain as a function of pump wavelength. Four-wave mixing experiments in both the normal and the anomalous dispersion regimes generated PMI frequency shifts that show good agreement with the predicted values over a 70 THz range. These results could lead to amplifiers and oscillators based on PMI.
Cross-phase modulation instability in photonic crystal fibers
J. S. Chen,
G. K. Wong,
S. G. Murdoch,
R. J. Kruhlak,
R. Leonhardt,
J. D. Harvey,
N. Y. Joly,
J. C. Knight
We report on the observation of cross-phase modulation instability in a highly nonlinear photonic crystal fiber. In such fibers the presence of higher orders of dispersion results in a complex phase-matching curve. We are able to observe this behavior experimentally and obtain excellent agreement between the measured and predicted shifts.
Raman-like light scattering from acoustic phonons in photonic crystal
fiber
P Dainese,
PSJ Russell,
GS Wiederhecker,
N Joly,
HL Fragnito,
V Laude,
A Khelif
Raman and Brillouin scattering are normally quite distinct processes that take place when light is resonantly scattered by, respectively, optical and acoustic phonons. We show how few-GHz acoustic phonons acquire many of the same characteristics as optical phonons when they are tightly trapped, transversely and close to modal cut-off, inside the wavelength-scale core of an air-glass photonic crystal fiber (PCF). The result is an optical scattering effect that closely resembles Raman scattering, though at much lower frequencies. We use photoacoustic techniques to probe the effect experimentally and finite element modelling to explain the results. We also show by numerical modelling that the cladding structure supports two phononic band gaps that contribute to the confinement of sound in the core. (c) 2006 Optical Society of America
Stimulated Brillouin scattering from multi-GHz-guided acoustic phonons
in nanostructured photonic crystal fibres
P. Dainese,
P. St. J. Russell,
N. Joly,
J. C. Knight,
G. S. Wiederhecker,
H. L. Fragnito,
V. Laude,
A. Khelif
Wavelength-scale periodic microstructuring dramatically alters the optical properties of materials. An example is glass photonic crystal fibre(1) ( PCF), which guides light by means of a lattice of hollow micro/nanochannels running axially along its length. In this letter, we explore stimulated Brillouin scattering in PCFs with subwavelength-scale solid silica glass cores. The large refractive-index difference between air and glass allows much tighter confinement of light than is possible in all-solid single-mode glass optical fibres made using conventional techniques. When the silica-air PCF has a core diameter of around 70% of the vacuum wavelength of the launched laser light, we find that the spontaneous Brillouin signal develops a highly unusual multi-peaked spectrum with Stokes frequency shifts in the 10-GHz range. We attribute these peaks to several families of guided acoustic modes each with different proportions of longitudinal and shear strain, strongly localized to the core(2,3). At the same time, the threshold power for stimulated Brillouin scattering(4) increases fivefold. The results show that Brillouin scattering is strongly affected by nanoscale microstructuring, opening new opportunities for controlling light-sound interactions in optical fibres.
Spectrally smooth supercontinuum from 350 nm to 3 mu m in sub-centimeter
lengths of soft-glass photonic crystal fibers.
FG Omenetto,
NA Wolchover,
MR Wehner,
M Ross,
A Efimov,
AJ Taylor,
VVRK Kumar,
AK George,
JC Knight, et al.
The conversion of light fields in photonic crystal fibers ( PCFs) capitalizes on the dramatic enhancement of several optical nonlinearities. We present here spectrally smooth, highly broadband supercontinuum radiation in a short piece of high-nonlinearity soft-glass PCF. This supercontinuum spans several optical octaves, with a spectral range extending from 350 nm to beyond 3000 nm. The selection of an appropriate propagation-length determines the spectral quality of the supercontinuum generated. Experimentally, we clearly identify two regimes of nonlinear pulse transformation: when the fiber length is much shorter than the dispersion length, soliton propagation is not important and a symmetric supercontinuum spectrum arises from almost pure self-phase modulation. For longer fiber lengths the supercontinuum is formed by the breakup of multiple Raman-shifting solitons. In both regions very broad supercontinuum radiation is produced. (c) 2006 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
