All-optical supercontinuum switching

Efficient all-optical switching is a challenging task as photons are bosons and cannot immediately interact with each other. Consequently, one has to resort to nonlinear optical interactions, with the Kerr gate being the classical example. However, the latter requires strong pulses to switch weaker ones. Numerous approaches have been investigated to overcome the resulting lack of fan-out capability of all-optical switches, most of which relied on types of resonant enhancement of light-matter interaction. Here we experimentally demonstrate a novel approach that utilizes switching between different portions of soliton fission induced supercontinua, exploiting an optical event horizon. This concept enables a high switching efficiency and contrast in a dissipation free setting. Our approach enables fan-out, does not require critical biasing, and is at least partially cascadable. Controlling complex soliton dynamics paves the way towards building all-optical logic gates with advanced functionalities. © 2020, The Author(s)

Third and fifth order nonlinear susceptibilities in thin HfO2 layers

Third harmonic generation (THG) from dielectric layers is investigated. By forming a thin gradient of HfO2 with continuously increasing thickness, we are able to study this process in detail. This technique allows us to elucidate the influence of the substrate and to quantify the layered materials third χ(3)(3ω: ω, ω, ω) and even fifth order χ(5)(3ω: ω, ω, ω, ω, − ω) nonlinear susceptibility at the fundamental wavelength of 1030 nm. This is to the best of our knowledge the first measurement of the fifth order nonlinear susceptibility in thin dielectric layers

Space-time coupling of shaped ultrafast ultraviolet pulses from an acousto-optic programmable dispersive filter

A comprehensive experimental analysis of spatio-temporal coupling effects inherent to the acousto-optic programmable dispersive filter (AOPDF) is presented. Phase and amplitude measurements of the AOPDF transfer function are performed using spatially and spectrally resolved interferometry. Spatio-temporal and spatio-spectral coupling effects are presented for a range of shaped pulses that are commonly used in quantum control experiments. These effects are shown to be attributable to a single mechanism: a group-delay--dependent displacement of the shaped pulse. The physical mechanism is explained and excellent quantitative agreement between the measured and calculated coupling speed is obtained. The implications for quantum control experiments are discussed.Comment: 8 pages, 6 figures; accepted for publication within JOSA

Génération et caractérisation d'impulsions façonnées - Application au contrôle spatio-temporel de la lumière diffusée

This PhD thesis concerns a range of technological studies and physical applications within the fields of ultrafast science and coherent control. From the technological point of view, we have performed a comprehensive study of space-time coupling within the 'Dazzler' AOPDF pulse shaper using interferometric techniques. For a while such limitations of '4f' zero-dispersion line pulse shapers have been widely documented; our results were the first to demonstrate, quantify and explain a parallel effect in this alternative device. From a control perspective, we have demonstrated exciting results about temporal refocusing of a broadband pulse that has been strongly distorted by a random, multiply scattering medium (i.e. the temporal analogue of the spatial speckle pattern). For this purpose a spatially resolved measurement of the spectral phase of the distorted pulse followed by open-loop feedback to a pulse shaper were implemented: as a result of the linearity of the scattering process, this pre-compensation has led to a spatially localized flat output spectral phase and hence a short pulse. This has already stimulated much interest amongst colleagues for diverse applications such as biological imaging or quantum optics studies.Cette thèse porte sur une série d'études technologiques et d'applications physiques dans les domaines de la dynamique ultrarapide et contrôle cohérent. Du point de vue technologique, nous avons effectué une étude approfondie de couplage spatio-temporel induit par l'interaction de l'onde optique avec une onde acoustique au sein d'un cristal non linéaire pour le façonnage de l'impulsion laser ultra courte. Cette étude a été menée en utilisant des techniques interférométriques. Ces effets bien connus dans les façonneurs d'impulsions utilisant une ligne 4f n'avaient jamais été mesurés dans ce type façonneur. Nos résultats ont été les premiers à les démontrer, les quantifier et les expliquer. Du point de vue du contrôle, nous avons mis en évidence des résultats très intéressants concernant la refocalisation temporelle d'une impulsion large bande fortement perturbée par un milieu multi-diffusif (i.e. l'analogue temporel de speckle spatiale). Pour cela nous avons d'eveloppé une mesure résolue spatialement de la phase spectrale de l'impulsion déformée suivie par une rétroaction en boucle ouverte permettant la correction en temps réelle de la phase grâce à un façonneur d'impulsions: en raison de la linéarité du processus de diffusion, cette compensation a permis de réaliser la recompression d'une impulsion laser en sortie de l''echantillon en un point donné (localisation spatiale) . Cela a suscité beaucoup d'intérêts parmi les collègues pour diverses applications telles que l'imagerie biologique ou pour des développements utilisant l'optique quantique

Generation and characterization of shaped femtosecond pulses and their application in spatio-temporal control of speckle pattern

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Simple route toward efficient frequency conversion for generation of fully coherent supercontinua in the mid-IR and UV range

Fiber supercontinua represent light sources of pivotal importance for a wide range of applications, ranging from optical communications to frequency metrology. Although spectra encompassing more than three octaves can be produced, the applicability of such spectra is strongly hampered due to coherence degradation during spectral broadening. Assuming pulse parameters at the cutting edge of currently available laser technology, we demonstrate the possibility of strongly coherent supercontinuum generation. In a fiber with two zero-dispersion wavelengths a higher-order soliton experiences a temporal breakdown, without any compression or splitting behavior, which leads to nearly complete conversion of input solitonic radiation into resonant nonsolitonic radiation in the dispersive wave regime. As the process is completely deterministic and shows little sensitivity to input noise, the resulting pulses appear to be compressible down to the sub-cycle level and may thus hold a new opportunity for direct generation of attosecond pulses in the visible to near ultraviolet wavelength range

Writing 3D Waveguides With Femtosecond Pulses in Polymers

We present novel waveguide writing concepts in bulk PMMA. The writing relies on laser induced modification tracks that are completely surrounding a waveguide core. We found the optimal parameters to construct highly reproducible, single-mode waveguides with minimal propagation losses down to 0.6 dB cm -1 . Employing the best geometry, we demonstrate 2D and 3D Y-splitters that are the building blocks for creating complex optical networks such as sensors or lab-on-chip devices in polymer materials

Path to high energy, high repetition rate tunable femtosecond ultraviolet pulse generation

We show that a combination of OPCPA and cascaded SFM can efficiently generate 100 μJ, MHz repetition rate, 50 fs, tunable pulses from 279 nm to 317 nm for seeding superconducting X-ray free electron lasers