We show that higher-order nonlinear indices (${n}_{4}$, ${n}_{6}$, ${n}_{8}$, ${n}_{10}$) provide the main defocusing contribution to self-channeling of ultrashort laser pulses in air and argon at 800 nm, contrast with previously accepted mechanism filamentation where plasma was considered as dominant process. Their consideration allows us reproduce experimentally observed intensities densities self-guided filaments.

We demonstrate a simple scheme to generate 0.4 mJ 11.5 fs laser pulses at 1.8 μm. Optical parametrically amplified are spectrally broadened by nonlinear propagation in an argon-filled hollow-core fiber and subsequently compressed 1.9 optical cycles linear through bulk material the anomalous dispersion regime. This pulse compression is confirmed numerical simulations.

While filaments are generally interpreted as a dynamic balance between Kerr focusing and plasma defocusing, the role of higher-order effect (HOKE) is actively debated potentially dominant defocusing contribution to filament stabilization. In pump-probe experiment supported by numerical simulations, we demonstrate transition two distinct filamentation regimes at 800 nm. For long pulses (1.2 ps), substantially contributes filamentation, while this vanishes for short (70 fs). These results...

We report the first (to our knowledge) experimental results and numerical simulations on mid-IR femtosecond pulse filamentation in argon using 0.1 TW peak-power, 80 fs, 3.9 μm pulses. A broadband supercontinuum spanning spectral range from 350 nm to 5 is generated, whereby about 4% of energy converted into 350-1700 region. These mid-IR-visible coherent continua offer a new, unique tool for time-resolved spectroscopy based laser source.

We observed the filamentation of mid-infrared ultrashort laser pulses (3.9 μm, 80 fs) in molecular gases. It efficiently generates a broadband supercontinuum over two octaves 2.5-6 μm spectral range, with red-shift up to 500 nm due Raman effect, which dominates blue shift induced by self-steepening and gas ionization. As result, conversion efficiency into Stokes region (4.3-6 μm) 65% is demonstrated.

We demonstrate the fabrication of arsenic- and antimony-free chalcogenide glasses compatible with glass fiber processing. Optical fibers distinct index profiles are presented characterized, namely, single-material or without a suspended core standard step-index varying diameter. In addition, we evidence their potential for nonlinear photonic devices in mid-infrared spectral region by means supercontinuum generation experiments femtosecond regime. Spectral broadenings extend on several...

We demonstrate 1.7–18 µm mid-infrared coherent supercontinuum generation by means of the full transmission window a unique dispersion-engineered step-index Ge-Se-Te fiber. Our study thus opens entire molecular fingerprint region to future chalcogenide fiber platforms.

Multimode optical fibers are essential in bridging the gap between nonlinear optics bulk media and single-mode fibers. The understanding of transition two fields remains complex due to intermodal processes spatiotemporal couplings, e.g., some striking phenomena observed with ultrashort pulses have not yet been unveiled such waveguides. Here we generalize concept conical waves described towards structured media, as multimode fibers, which only a discrete finite number modes can propagate....

Propagation-invariant or nondiffracting optical beams have received considerable attention during the last two decades. However, pulsed nature of light waves and structured property media like waveguides are often overlooked. We here present a four-dimensional spatiotemporal approach that extends unifies both concepts conical helicon beams, mainly studied in bulk media. By taking advantage tight correlations between spatial modes, topological charges, frequencies embedded an field, we reveal...

We provide a complete analysis, from theory to experiment, of the spontaneous emergence discretized conical wave X-type (i.e., localized 2D+1 space-time wavepacket) when an intense ultrashort pulse nonlinearly propagates in multimode fiber. In particular, we reveal that this spatiotemporal phenomenon corresponds broadband intermodal dispersive emission unsteady structure formed during nonlinear propagation. Theoretical phase-matching predictions are experimentally and numerically confirmed...

A phase-matching-free ultrashort pulse retrieval based on the defocusing of a laser-induced plasma is presented. In this technique, pump ionizes rare gas providing lens whose creation time ultrafast. probe propagating through experiences switch its divergence. The spectrum diverging part, isolated by coronograph, measured as function pump-probe delay, spectrogram that allows for comprehensive characterization temporal properties pulse. method, called PI-FROSt "plasma-induced...

We experimentally observed optical rogue wave statistics during high power femtosecond pulse filamentation in air. characterized wavelength-dependent intensity fluctuations across 300 nm broadband filament spectra generated by pulses with several times the critical for filamentation. show how vary from a near-Gaussian distribution vicinity of pump to long tailed "L-shaped" at short wavelength and edges. The results are interpreted terms noise transfer via self-phase modulation.

The exact quantum time-dependent optical response of hydrogen under strong-field near-infrared excitation is investigated and compared to the perturbative model widely used for describing effective atomic polarization induced by intense laser fields. By solving full 3D Schr\"odinger equation, we exhibit a supplementary, quasi-instantaneous defocusing contribution missing in weak-field polarization. We show that this effect far from being negligible, particular when closures ionization...

Space–time light structuring has emerged as a very powerful tool for controlling the propagation dynamics of pulsed beams. The ability to manipulate and generate space–time distributions been remarkably enhanced in past few years, letting us envision applications across entire spectrum optics. invariant optical wavepackets manipulated up now are usually two-dimensional objects (one space dimension time) whose mode-resolved spectra lie conical section. Using simple symmetry invariance...

A physical system is considered chiral when it can be distinguished from its mirror image, regardless of the applied translation and rotation. An electromagnetic wave through two essential forms angular momenta: spin orbital. Although interaction between momentum light matter now well known, way possessing an orbital interacts with a topic growing interest. In particular, specific signatures light–matter that depend on sign remain elusive. We demonstrate here chirality takes place as soon...

We numerically investigate the pulse compression mechanism in infrared spectral range based on successive action of nonlinear propagation a hollow-core fiber followed by linear through bulk material. found an excellent agreement simulated properties with experimental results at 1.8 $\ensuremath{\mu}$m two-optical-cycle regime close to Fourier limit. In particular, phase asymmetry attributable self-steepening combined self-phase modulation is necessary prerequisite for subsequent compensation...

As a contribution to the ongoing controversy about role of higher-order Kerr effect (HOKE) in laser filamentation, we first provide thorough details protocol that has been employed infer HOKE indices from experiment. Next, discuss potential sources artifact experimental measurements these terms and show neither value observed birefringence, nor its inversion, intensity at which it is observed, appear be flawed. Furthermore, argue that, independently on our values, principle including...

We demonstrate a polarized all-normal dispersion supercontinuum generated in birefringent silica microstructured fiber spanning beyond 2.5 µm. To our knowledge, this is the spectra reaching furthest mid-infrared ever normal fibers. The generation process was studied experimentally and numerically with 70 fs pump pulses operating at different wavelengths on short propagation distances of 48 mm 122 mm. operation limited by zero-dispersion wavelength 2.56 µm spectral broadening stopped OH...

In this paper, we present an efficient numerical model able to solve the vectorial nonlinear pulse propagation equation in circularly symmetric multimode waveguides. The algorithm takes advantage of conservation total angular momentum light upon and into account nature propagating modes, making it particularly relevant for studies ring-core fibers. While conventional solvers exhibit a computational complexity scaling as N mode 4 , where is number considered solver scales 3/2 . As first...

The authors demonstrate optimal control of the propagation ultrashort, ultraintense (multiterawatt) laser pulses in air over distances up to 36m a closed-loop scheme. They optimized three spectral ranges within white-light continuum as well ionization efficiency. Optimization results signal enhancements by typical factors 2 and 1.4 for target parameters. optimization shorter reducing their chirp case generation, while they correct pulse from its defects set filamentation onset near detector...

In this article, we derive the general exact solution of modulation instability gain. The described here is valid for 1-D, 2-D, and 3-D cases considering any temporal response function medium with possible higher order Kerr nonlinearities. particular, show that gain induced by initial condition dependent, while usual calculations do not lead to such a dependence. Applications current high-interest nonlinear propagation problems, as 1-D optical fiber delayed Raman 2-D filamentation in gases,...

We demonstrate that filaments generated by ultrashort laser pulses can induce a remarkably large birefringence in Argon over its whole length, resulting an ultrafast "half-wave plate" for copropagating probe beam. This originates from the difference between nonlinear refractive indices induced filament on axes parallel and orthogonal to polarization. An angle of 45 degrees polarizations allows realization Kerr-gates, with switching time ultimately limited duration filamenting pulse.