arXiv subjects

A. Kudlinski

Publications and source records attributed to A. Kudlinski.

16 recordsLinked to original sources

arXiv2026

Picosecond Supercontinuum Generation in All-Normal Dispersion Optical Fibers Enabled by Polarization Instabilities

Supercontinuum generation in all-normal-dispersion optical fibers has so far been predominantly explored under femtosecond pumping conditions. Here, we demonstrate that efficient and broadband supercontinuum generation can also be achieved in the long picosecond regime by pumping a highly birefringent all-normal-dispersion silica-based photonic crystal fiber at 1064 nm. The observed spectral broadening results from the combined action of polarization modulation instability and cascaded Raman scattering, enabling octave-spanning spectra extending from 600 nm to 1650 nm. These results establish a distinct operating regime for supercontinuum generation and open new perspectives for robust, high-power broadband fiber sources.

physics.optics↗

arXiv2025

Two-photon microscopy using picosecond pulses from four-wave mixing in a Yb-doped photonic crystal fiber

Two-photon microscopy (TPM) enables deep tissue imaging but requires excitation pulses that have a large product of average and peak power, typically supplied by femtosecond solid-state lasers. However, these lasers are bulky and femtosecond pulses require careful dispersion management to avoid pulse broadening, particularly when delivery fibers are used. Here we present a compact, fiber-based picosecond laser source operating at 790 nm for TPM using a ytterbium-doped photonic crystal fiber (Yb-doped PCF). The Yb-doped PCF simultaneously amplifies 1064 nm input pulses and efficiently converts them to 790 nm via four-wave mixing, generating pulses with a peak power of up to ~3.8 kW. The source has a variable repetition rate (1.48 MHz-14.78 MHz), enabling the two-photon excitation fluorescence signal to be maximized in the presence of excitation saturation. We benchmark our picosecond laser source against a femtosecond Ti:Sapphire laser for TPM of stained Convallaria majalis samples and demonstrate comparable fluorescence signal when the two-photon excitation conditions are matched.

physics.optics↗

arXiv2024

A hollow-core fiber based stand-alone multimodal (2-photon, 3-photon, SHG, THG) nonlinear flexible imaging endoscope

Multimodal nonlinear endoscopes have been a topic of intense research over the past two decades, enabling sub-cellular and label-free imaging in areas not reachable with table-top microscopes. They are sophisticated systems that can be implemented on an optical table in a lab environment, but they cannot be easily moved within or out of the lab. We present here a multimodal and flexible nonlinear endoscope system able to perform two photon excited fluorescence and second harmonic generation imaging with a stand-alone and moveable kart integrating a compact ultrashort laser source. In addition, the system can perform three photon excited fluorescence and third harmonic generation thanks to a delivery optical fiber used to deliver ultrashort pulses from massive and not movable laser systems into the stand-alone kart. The endoscopic fiber probes and delivery optical fibers are based on functionalized negative curvature hollow core fibers. The endoscope distal head has a diameter <2.2mm and can perform nonlinear imaging at max 10 frames/s over a field of view up to 600 $μ$m with a ~1 $μ$m spatial resolution.

physics.optics↗

arXiv2021

Modulational instability in optical fibers with randomly-kicked normal dispersion

We study modulational instability (MI) in optical fibers with random group velocity dispersion (GVD) generated by sharply localized perturbations of a normal GVD fiber that are either randomly or periodically placed along the fiber and that have random strength. This perturbation leads to the appearance of low frequency MI side lobes that grow with the strength of the perturbations, whereas they are faded by randomness in their position. If the random perturbations exhibit a finite average value, they can be compared with periodically perturbed fibers, where Arnold tongues appear. In that case, increased randomness in the strengths of the variations tends to affect the Arnold tongues less than increased randomness in their positions.

physics.optics↗

arXiv2018

Collision between a dark soliton and a linear wave in an optical fiber

We report an experimental observation of the collision between a linear wave propagating in the anomalous dispersion region of an optical fiber and a dark soliton located in the normal dispersion region. This interaction results in the emission of a new frequency component whose wavelength can be predicted using phase-matching arguments. The measured efficiency of this process shows a strong dependency with the soliton grayness and the linear wave wavelength, and is in a good agreement with theory and numerical simulations.

physics.optics↗

arXiv2018

Two-dimensional nonlinear modes and frequency combs in bottle microresonators

We investigate theoretically frequency comb generation in a bottle microresonator accounting for the azimuthal and axial degrees of freedom. We first identify a discrete set of the axial nonlinear modes of a bottle microresonator that appear as tilted resonances bifurcating from the spectrum of linear axial modes. We then study azimuthal modulational instability of these modes and show that families of 2D soliton states localized both azimuthally and axially bifurcate from them at critical pump frequencies. Depending on detuning, 2D solitons can be either stable, or form persistent breathers, chaotic spatio-temporal patterns, or exhibit collapse-like evolution.

physics.optics↗

arXiv2017

Emission of dispersive waves from solitons in axially-varying optical fibers

The possibility of tailoring the guidance properties of optical fibers along the same direction as the evolution of the optical field allows to explore new directions in nonlinear fiber optics. The new degree of freedom offered by axially-varying optical fibers enables to revisit well-established nonlinear phenomena, and even to discover novel short pulse nonlinear dynamics. Here we study the impact of meter-scale longitudinal variations of group velocity dispersion on the propagation of bright solitons and on their associated dispersive waves. We show that the longitudinal tailoring of fiber properties allows to observe experimentally unique dispersive waves dynamics, such as the emission of cascaded, multiple or polychromatic dispersive waves.

nlin.PS↗

arXiv2017

Spectral wings of the fiber supercontinuum and the dark-bright soliton interaction

We present experimental and numerical data on the supercontinuum generation in an optical fiber pumped in the normal dispersion range where the seeded dark and the spontaneously generated bright solitons contribute to the spectral broadening. We report the dispersive radiation arising from the interaction of the bright and dark solitons. This radiation consists of the two weak dispersing pulses that continuously shift their frequencies and shape the short and long wavelength wings of the supercontinuum spectrum.

physics.optics↗

arXiv2016

Heteroclinic structure of parametric resonance in the nonlinear Schrödinger equation

We show that the nonlinear stage of modulational instability induced by parametric driving in the {\em defocusing} nonlinear Schrödinger equation can be accurately described by combining mode truncation and averaging methods, valid in the strong driving regime. The resulting integrable oscillator reveals a complex hidden heteroclinic structure of the instability. A remarkable consequence, validated by the numerical integration of the original model, is the existence of breather solutions separating different Fermi-Pasta-Ulam recurrent regimes. Our theory also shows that optimal parametric amplification unexpectedly occurs outside the bandwidth of the resonance (or Arnold tongues) arising from the linearised Floquet analysis.

nlin.PS↗

arXiv2016

Emission of dispersive waves from a train of dark solitons in optical fibers

We report the experimental observation of multiple dispersive waves emitted in the anomalous dispersion region of an optical fiber from a train of dark solitons. Each individual dispersive wave can be associated to one particular dark soliton of the train, using phase-matching arguments involving higher-order dispersion and soliton velocity. For a large number of dark solitons (>10), we observe the formation of a continuum associated with the efficient emission of dispersive waves.

nlin.PS↗

arXiv2015

Optimal frequency conversion in the nonlinear stage of modulation instability

We investigate multi-wave mixing associated with the strongly pump depleted regime of induced modulation instability (MI) in optical fibers. For a complete transfer of pump power into the sideband modes, we theoretically and experimentally demonstrate that it is necessary to use a much lower seeding modulation frequency than the peak MI gain value. Our analysis shows that a record 95 % of the input pump power is frequency converted into the comb of sidebands, in good quantitative agreement with analytical predictions based on the simplest exact breather solution of the nonlinear Schrödinger equation.

physics.optics↗

arXiv2015

Modulational instability in dispersion-kicked optical fibers

We study, both theoretically and experimentally, modulational instability in optical fibers that have a longitudinal evolution of their dispersion in the form of a Dirac delta comb. By means of Floquet theory, we obtain an exact expression for the position of the gain bands, and we provide simple analytical estimates of the gain and of the bandwidths of those sidebands. An experimental validation of those results has been realized in several microstructured fibers specifically manufactured for that purpose. The dispersion landscape of those fibers is a comb of Gaussian pulses having widths much shorter than the period, which therefore approximate the ideal Dirac comb. Experimental spontaneous MI spectra recorded under quasi continuous wave excitation are in good agreement with the theory and with numerical simulations based on the generalized nonlinear Schrödinger equation.

physics.optics↗

arXiv2013

Real time noise and wavelength correlations in octave-spanning supercontinuum generation

We use dispersive Fourier transformation to measure shot-to-shot spectral instabilities in femtosecond supercontinuum generation. We study both the onset phase of supercontinuum generation with distinct dispersive wave generation, as well as a highly-unstable supercontinuum regime spanning an octave in bandwidth. Wavelength correlation maps allow interactions between separated spectral components to be identified, even when such interactions are not apparent in shot-to-shot or average measurements. Experimental results are interpreted using numerical simulations. Our results show the clear advantages of dispersive Fourier transformation for studying spectral noise during supercontinuum generation.

physics.optics↗

arXiv2012

Dynamics of the modulation instability spectrum in optical fibers with oscillating dispersion

A simple analytical model is developed to analyze and explain the complex dynamics of the multi-peak modulation instability spectrum observed in dispersion oscillating optical fibers [M. Droques et al., 37, 4832-4834 Opt. Lett., (2012)]. We provide a simple expression for the local parametric gain which shows that each of the multiple spectral components grows thanks to a quasi-phase-matching mechanism due to the periodicity of the waveguide parameters, in good agreement with numerical simulations and experiments. This simplified model is also successfully used to tailor the multi-peak modulation instability spectrum shape. These theoretical predictions are confirmed by experiments.

physics.optics↗

arXiv2012

Real-time full bandwidth measurement of spectral noise in supercontinuum generation

The ability to measure real-time fluctuations of ultrashort pulses propagating in optical fiber has provided significant insights into fundamental dynamical effects such as modulation instability and the formation of frequency-shifting rogue wave solitons. We report here a detailed study of real-time fluctuations across the full bandwidth of a fiber supercontinuum which directly reveals the significant variation in measured noise statistics across the spectrum, and which allows us to study correlations between widely separated spectral components. For two different propagation distances corresponding to the onset phase of spectral broadening and the fully-developed supercontinuum, we measure real time noise across the supercontinuum bandwidth, and we quantify the supercontinuum noise using statistical higher-order moments and a frequency-dependent intensity correlation map. We identify correlated spectral regions within the supercontinuum associated with simultaneous sideband generation, as well as signatures of pump depletion and soliton-like pump dynamics. Experimental results are in excellent agreement with simulations.

physics.optics↗

arXiv2008

Experimental demonstration of multi-watt CW supercontinuum tailoring in photonic crystal fibers

We demonstrate experimentally that the spectral broadening of CW supercontinuum can be controlled by using photonic crystal fibers with two zero-dispersion wavelengths pumped by an Yb fiber laser at 1064 nm. The spectrum is bounded by two dispersive waves whose spectral location depends on the two zero-dispersion wavelengths of the fiber. The bandwidth of the generated spectrum and the spectral power density may thus be tailored for particular applications, such as high-resolution optical coherence tomography or optical spectroscopy.

physics.optics↗