A5063937312- Photonic Crystal and Fiber Optics
- Advanced Fiber Laser Technologies
- Optical Network Technologies
- Advanced Fiber Optic Sensors
- Solid State Laser Technologies
- Italian Literature and Culture
- Semiconductor Lasers and Optical Devices
- Laser-Matter Interactions and Applications
- Atmospheric aerosols and clouds
- Laser Design and Applications
- Optical Wireless Communication Technologies
- Advanced Optical Sensing Technologies
- Photorefractive and Nonlinear Optics
- Adaptive optics and wavefront sensing
- Historical and Literary Analyses
- Italian Fascism and Post-war Society
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Linguistics and Discourse Analysis
- Translation Studies and Practices
- Linguistic Studies and Language Acquisition
- Atmospheric and Environmental Gas Dynamics
- Educational and Social Studies
- Optical Systems and Laser Technology
- Meteorological Phenomena and Simulations
Office National d'Études et de Recherches Aérospatiales
2014-2024
Université Paris-Saclay
2018-2024
CEA LETI
2023
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2023
CEA Grenoble
2023
Université Paris Cité
2021
Laboratoire d'Optique Appliquée
2007-2019
Université Paris Nanterre
2010-2014
Infection et inflammation
2001-2014
Université d'Avignon et des Pays de Vaucluse
2001-2014
We report experimental results and theoretical analysis of coherent beam combining with active phase control fiber shaping. An original optical configuration for target-in-the-loop single-mode amplifier through turbulence is presented, a lambda/15 residual error. The demonstrate that detection subsystem aperture reduction paramount to lower sensitivity backward when using detector in the laser emitter plane. In this configuration, achieved on remote scattering surface sole compensation...
Active coherent beam combination using a 7-non-coupled core, polarization maintaining, air-clad, Yb-doped fiber is demonstrated as monolithic and compact power-scaling concept for ultrafast lasers. A microlens array matched to the multicore an active phase controller composed of spatial light modulator applying stochastic parallel gradient descent algorithm are utilized perform combining in tiled aperture geometry. The mitigation nonlinear effects at pulse energy 8.9 µJ duration 860 fs...
We report on a coherent wind lidar built with two coherently-beam-combined fiber amplifiers. The performances of the combined-amplifier and single-amplifier are compared using criterions: carrier-to-noise ratio speed noise floor. In both cases, not degraded combined source close to theoretical optimum. Combined sources well suited improve accuracy, range, integration time.
This work compares several Yb-doped large mode area (LMA) fiber amplifiers operating in the ∼50 ns regime at 1030 nm designed for airborne wind lidar application. The sinusoidal phase modulation applied to signal enhances SBS threshold by a factor 8.8 compared single frequency operation while still complying with receiver spectral requirements. By combining this short, highly doped LMA fibers, more than 10 kW output peak power has been reached 50 pulses 40 kHz repetition rate.
We propose a beam cleanup setup to convert multimode into single-mode by use of the Brillouin effect in gradient-index (GI) fiber. Phase conjugation and regimes highly fibers are discussed, self-aligned GI fiber cavity is presented. report preliminary conversion from an M2=6.5 M2=1.3 with 31% efficiency.
The influence of air turbulence on femtosecond laser filamentation is studied experimentally and numerically for powers a few critical powers. Air in the path beam prior to induces large pointing formation instability attributed an increase self-focusing distance higher modulational presence turbulence. By contrast, previously formed filaments are robust both terms accuracy survival when crossing turbulent air.
Lidar
We report a high power, single frequency, linearly polarized master oscillator power amplifier emitting 110 ns, 1 kW peak pulses at 2050 nm. A 20% slope efficiency and beam quality of M2=1.21 are achieved with three-stage double-clad Tm(3+)-doped fiber architecture. Various pump schemes compared leading to the conclusion that 793 nm wavelength is most efficient for amplification Based on numerical simulations, Brillouin gain coefficient around 2 μm in Tm(3+) highly doped silica estimated...
In the framework of space-borne CO2 lidar development, transmitter is a critical unit. We report on development and assessment performances 2-μm single-frequency thulium fiber laser pumped Q-switched Ho:YLF laser. To fulfill requirements space-based operation, master oscillator power amplifier architecture has been chosen, works in double-pulse operation. The can generate single-mode dual wavelength emission "ON" "OFF" around R30e line 20013←00001 band CO212. It delivers pair OFF-ON pulses...
Two important enabling technologies for pulsed coherent detection wind lidar are the laser and real-time signal processing. In particular, fiber is limited in peak power by nonlinear effects, such as stimulated Brillouin scattering (SBS). We report on various that have been developed to mitigate SBS increase 1.5-μm lasers, special large mode area designs or strain management. Range-resolved profiles up a record range of 16 km within 0.1-s averaging time obtained thanks those high-peak...
We present a novel interferometric technique dedicated to the measurement of relative phase differences (pistons) and tilts periodically segmented wavefront. Potential applications include co-phasing mirrors Keck-like telescopes as well coherent laser beam combining. The setup only requires holes mask selecting center part each element, diffracting component, camera. Recorded interferogram is made many subareas with sinusoidal fringe pattern. From pattern, piston extracted from shift...
A laser testbed based on active coherent beam combination (CBC) of seven 1.5 µm, 3 W fiber amplifiers was developed for applications requiring high power such as density deposition targets or free space communication. For the first time to our knowledge, frequency-tagging locking optical coherence by single-detector electronic-frequency tagging technique implemented in field real atmospheric turbulence conditions a target-in-the-loop configuration. Successful achieved after horizontal...
New architectures for telescopes or powerful lasers require segmented wave front metrology. This paper deals with a new interferometric sensing technique called PISTIL (PISton and TILt), able to recover both piston tilts of segment beams. The main advantages the are absence reference arm an access tilt information. An explanation principle, as well experimental implementation use active mirror, presented. Measurement errors λ/200 40 µrad have been achieved, beyond performances requested...
Active phase locking of a multicore erbium-doped fiber amplifier is demonstrated for 180 ns narrow-linewidth pulses at 1545 nm. A spatial light modulator used the input to control optical 7 beams injected in hexagonally-arranged cores, ensuring efficient combining through SPGD algorithm. At output, performed using diffractive element. This experiment establishes amplifiers as promising way scale energy Brillouin-limited pulsed LIDAR applications. We also present simple lensless technique...
Coherent beam combining of fiber amplifier arrays is a promising way to increase power lasers, and overcome the physical limitations laser scaling. We performed coherent using active control phase each amplifier. The fluctuations in amplifiers have been measured their effect on process stability evaluated. extended technique perform wavefront shaping, order deliver high brightness after turbulent atmospheric propagation. present experimental results exhibiting capability modulation...
We demonstrate spectral coherent beam combining of two femtosecond fiber chirped-pulse amplifiers seeded by a common oscillator. Using active phase stabilization based on an electro-optic modulator, average power 10 W before compression and high gain factor 30 dB are obtained. At this value, 130 fs pulses with width 19 nm can be generated, highlighting the strong potential pulse synthesis for reduction minimum duration ultrashort in amplifiers.
Atmospheric gravity waves and turbulence generate small-scale fluctuations of wind, pressure, density, temperature in the atmosphere. These represent a real hazard for commercial aircraft are known by generic name clear-air (CAT). Numerical weather prediction models do not resolve CAT therefore provide only probability occurrence. A ground-based Rayleigh lidar was designed implemented to remotely detect characterize atmospheric variability induced vertical scales between 40 m few hundred...
We experimentally investigate the impact of spectral phase mismatch on coherent beam combining two femtosecond fiber chirped-pulse amplifiers. By measuring differential phase, both linear and nonlinear contributions are identified. An accumulated as high 6 rad has been measured, for which a combination efficiency 91% can be obtained by symmetrizing pump injection powers. This also allows us to quantitatively separate spatial temporal nonperfect efficiency.
The multimode and depolarized output beam of a highly diode-pumped Yb-doped fiber amplifier is converted to diffraction-limited, linearly polarized by self-referencing two-wave-mixing process in an infrared-sensitive photorefractive crystal (Rh:BaTiO3). As much as 11.6 W single-mode achieved with 78% multimode-to-single-mode conversion efficiency.
Multifilament core (MFC) fibers are a new type of microstructured fiber recently introduced. We investigate their properties using finite element modeling and show that the equivalent step index based on moments theory does not provide similar properties. propose an effective fundamental space filling mode which allows to predict MFC semi-analytical modeling. Good resistance bending is thus attributed increased due high filaments.
We report on single-frequency all-fiber amplifiers based Er-Yb doped P2O5-Al2O3-SiO2 fibers. Peak power up to 1120 W at 1545 nm for 108 ns pulse duration has been obtained with 18 % slope-efficiency. Continuous-wave operation generated 14 W.
This paper reports the main characteristics of Stokes spectra for typical pumped and unpumped Erbium-Ytterbium doped fibers. Doped fibers show shorter Brillouin shifts their are up to 1.6 times broader than undoped Those composed several peaks originating from longitudinal acoustic modes. The effective gain secondary modes can be as large 20% peak gain. They merge into a more complex structure largest cores. Simulations allow relate these influence codoping index profile inhomogeneity. An...