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Cid B. de Araújo

Publications and source records attributed to Cid B. de Araújo.

15 recordsLinked to original sources
arXiv2026

Replica Symmetry Breaking in the Quasi Mode Locked Regime of Titanium Sapphire Lasers

Recent observations of replica symmetry breaking (RSB) in ytterbium-based mode-locked fiber lasers have revealed glassy behavior in the quasi-mode-locked (QML) regime. Here, we investigate whether this behavior is restricted to a specific laser implementation or represents a more general feature of mode-locked systems. By analyzing statistical correlations of spectral intensity fluctuations through the Parisi overlap and Pearson correlation parameters, we study two Titanium:sapphire laser systems: a homemade cavity and a commercial laser. In both cases, clear signatures of RSB are observed in the QML regime, while replica-symmetric behavior is recovered in the amplified spontaneous emission (ASE) and standard mode-locked (SML) regimes. These results demonstrate the occurrence of RSB in Titanium:sapphire lasers and support the interpretation of the QML regime as a photonic glassy phase. Together with previous observations in ytterbium-based fiber lasers, these findings suggest that the connection between QML dynamics and RSB may be a general feature of mode-locked laser systems.

physics.optics↗
arXiv2026

Observation of Replica Symmetry Breaking in Filamentation and Multifilamentation

We report the experimental observation and characterization of Replica Symmetry Breaking (RSB) manifestation while analyzing the transverse intensity profile of pulses in filamentation experiments using sapphire crystal and distilled water, excited by a femtosecond laser centered at 800 nm. The RSB arises from the competition between self-focusing and plasma defocusing, subject to local fluctuations in the nonlinear refractive index generated by plasma via multiphoton excitation, which subsequently promotes frustration among modes. Our results confirm the existence of glassy-like photonic states not only in multifilamentation, as previously reported [W. Ettoumi, J. Kasparian, and J. Wolf, "Spin-glass model governs laser multiple filamentation," Phys. Rev. Lett., vol. 115, no. 3, pp. 033902, 2015], but also in the generation of a single filament and in filamentation accompanied by conical emission. These findings improve the understanding of statistical nonlinear optics by establishing connections with magnetism and highlighting the glassy-like behavior of light in the context of ultrafast optical phenomena.

physics.optics↗
arXiv2025

Multiple Temporal Compression as a method to control the generation of bright and dark solitons

Recently published works have shown that the Multiple Temporal Compression (MTC) method is a more efficient approach for generation of multiple bright solitons in stacked waveguides, in comparison to the traditional soliton-fission technique. In the present paper, we performed systematic computer simulations of the appropriate generalized nonlinear Schrödinger equation to extend the MTC method for generation of dark solitons through controlled interactions of bright solitons in waveguiding systems with the normal group-velocity dispersion. Further, the generated dark solitons are demonstrated to be useful for accurately governing the dynamics of bright solitons generation in complex systems based on stacked waveguides. Therefore, we report scenarios that provide mitigation or switching of the energy transfer during bright-soliton collisions, along with the ability of the cascaded MTC processes to increase the number of the generated solitons. These results underscore the potential of the MTC as a versatile method for managing the propagation dynamics of multiple temporal bright and dark solitons produced by a single input pulse, with possible applications for the design of optical devices.

physics.optics↗
arXiv2023

Generation of robust temporal soliton trains by the multiple-temporal-compression (MTC) method

We report results of systematic numerical analysis for multiple soliton generation by means of the recently reported multiple temporal compression (MTC) method, and compare its efficiency with conventional methods based on the use of photonic crystal fibers (PCFs) and fused silica waveguides (FSWs). The results show that the MTC method is more efficient to control the soliton fission, giving rise to a larger number of fundamental solitons with high powers, that remain nearly constant over long propagation distances. The high efficiency of the MTC method is demonstrated, in particular, in terms of multiple soliton collisions and the Newton's-cradle phenomenology.

physics.optics↗
arXiv2023

Generation of multiple ultrashort solitons in a third-order nonlinear composite medium with self-focusing and self-defocusing nonlinearities

Theoretical consideration of the propagation of femtosecond-Gaussian pulses in a 1D composite medium, consisting of alternating self-focusing (SF) and self-defocusing (SDF) waveguide segments with normal group-velocity dispersion predicts the generation of trains of bright solitons when an optical pulse first propagates in the SF segment, followed by the SDF one. The multiple temporal compression (MTC) process, based on this setting, offers a method for controllable generation of multiple ultrashort temporal solitons. Numerical solutions of the generalized nonlinear Schrödinger equation modeling this system demonstrate that the intrapulse Raman scattering plays a major role in the temporal and spectral dynamics. Collisions between ultrashort solitons with different central wavelengths are addressed too. The paper provides, for the first time, a procedure for producing controllable trains of ultrashort temporal solitons by incident optical pulses propagating in a composite medium.

physics.optics↗
arXiv2020

Observation and analysis of creation, decay, and regeneration of annular soliton clusters in a lossy cubic-quintic optical medium

We observe and analyze formation, decay, and subsequent regeneration of ring-shaped clusters of (2+1)-dimensional spatial solitons (filaments) in a medium with the cubic-quintic (focusing-defocusing) self-interaction and strong dissipative nonlinearity. The cluster of filaments, that remains stable over ~17.5 Rayleigh lengths, is produced by the azimuthal modulational instability from a parent ring-shaped beam with embedded vorticity l = 1. In the course of still longer propagation, the stability of the soliton cluster is lost under the action of nonlinear losses. The annular cluster is then spontaneously regenerated due to power transfer from the reservoir provided by the unsplit part of the parent vortex ring. A (secondary) interval of the robust propagation of the regenerated cluster is identified. The experiments use a laser beam (at wavelength 800 nm), built of pulses with temporal duration 150 fs, at the repetition rate of 1 kHz, propagating in a cell filled by liquid carbon disulfide. Numerical calculations, based on a modified nonlinear Schrödinger equation which includes the cubic-quintic refractive terms and nonlinear losses, provide results in close agreement with the experimental findings.

nlin.PS↗
arXiv2016

Photonic ferromagnetic-like spontaneous mode-locking phase transition with replica symmetry breaking in multimode Nd:YAG laser

The recent reports of the replica symmetry breaking (RSB) phenomenon in photonic experiments [1-5] boosted the understanding of the role of disorder in multimode lasers, as well as helped to settle enlightening connections [6-13] with the statistical physics of complex systems. RSB manifests when identically-prepared system replicas reach distinct states, yielding different measures of observable quantities [14]. Here we demonstrate the RSB in the spontaneous mode-locking regime of a conventional multimode Nd:YAG laser in a closed cavity. The underlying mechanism is quite distinct from that of the RSB spinglass phase in cavityless random lasers with incoherently-oscillating modes. Here, a specific nonuniform distribution of the gain takes place in each pulse, and frustration is induced since the coherent oscillation of a given subset of longitudinal modes dominates and simultaneously inhibits the others. Nevertheless, when high losses are introduced only the replica-symmetric amplified stimulation emission is observed. We therefore suggest that the RSB transition can be used as an identifier of the threshold in standard multimode lasers, as recently proposed and demonstrated for random lasers [1,2].

physics.optics↗
arXiv2016

Observation of Replica Symmetry Breaking in the 1D Anderson Localization Regime in an Erbium-Doped Random Fiber Laser

The analogue of the paramagnetic to spin-glass phase transition in disordered magnetic systems, leading to the phenomenon of replica symmetry breaking, has been recently demonstrated in a two-dimensional random laser consisting of an organic-based amorphous solid-state thin film. We report here the first demonstration of replica symmetry breaking in a one-dimensional photonic system consisting of an erbium-doped random fiber laser operating in the continuous-wave regime based on a unique random fiber grating system, which plays the role of the random scatterers and operates in the Anderson localization regime. The clear transition from a photonic paramagnetic to a photonic spin glass phase, characterized by the probability distribution function of the Parisi overlap, was verified and characterized. In this unique system, the radiation field interacts only with the gain medium, and the fiber grating, which provides the disordered feedback mechanism, does not interfere with the pump.

physics.optics↗
arXiv2016

Robust self-trapping of vortex beams in a saturable optical medium

We report the first observation of robust self-trapping of vortex beams propagating in a uniform condensed medium featuring local saturable self-focusing nonlinearity. Optical vortices with topological charge m=1, that remain self-trapped over ~ 5 Rayleigh lengths, are excited in carbon disulfide using a helical light beam at 532 nm and intensities from 8 to 10 GW/cm^2. At larger intensities, the vortex beams lose their stability, spontaneously breaking into two fragments. Numerical simulations based on the nonlinear Schrödinger equation including the three-photon absorption and nonpolynomial saturation of the refractive nonlinearity demonstrate close agreement with the experimental findings.

physics.optics↗
arXiv2015

Random lasers, Lévy statistics and spin glasses: Synergy between photonics and complex systems

Random lasers have been recently approached as a photonic platform for disordered complex systems, such as spin glasses. In this work, using a Nd$^{3+}$:YBO$_3$ random laser system operating in the nonresonant (diffusive) feedback regime, we measured the distinct statistics of intensity fluctuations and show the physical origin of the complex interplay between the Lévy regime and the replica-symmetry-breaking transition to the photonic spin-glass phase. A novel result is reported: the unsaturated spin-glass behavior for high excitation pulse energies, not observed for systems with coherent feedback. Our experimental findings are corroborated by the present theoretical analysis. The results herein presented universalize the recent observation consistent with replica symmetry breaking in random lasers with coherent feedback, and also advance on the characterization of the fluctuation statistics of the photonic spin-glass phase, supported by recent theoretical works on the nonlinear optics of complex photonic systems.

physics.optics↗
arXiv2015

Optical vortices: the concept of topological potential and analogies with two-dimensional electrostatics

We show how the phase profile of a distribution of topological charges (TC) of an optical vortex (OV) can be described by a potential analogous to the Coulomb's potential for a distribution of electric charges in two-dimensional electrostatics. From what we call the Topological Potential (TP), the properties of TC multipoles and a 2D radial distribution were analyzed. The TC multipoles have a transverse profile that is topologically stable under propagation and may be exploited in optical communications; on the other hand, the 2D distributions can be used to tune the transverse forces in optical tweezers. Considering the analogies with the electrostatics formalism, it is also expected that the TP allows the tailoring of OV for specific applications.

physics.optics↗
arXiv2014

Nonlinearity management of photonic composites and observation of spatial-modulation instability due to quintic nonlinearity

We present a procedure for nonlinearity management of metal-dielectric composites. Varying the volume fraction occupied by silver nanoparticles suspended in acetone we could cancel the refractive index related to the third-order susceptibility, $χ_{eff}^{(3)}$, and the nonlinear refraction behavior was due to the fifth-order susceptibility, $χ_{eff}^{(5)}$. Hence, in a cross-phase modulation experiment, we demonstrated for the first time the effect of spatial-modulation- instability due to $χ_{eff}^{(5)}$. The results are corroborated with numerical calculations based on a generalized Maxwell-Garnet model.

physics.optics↗
arXiv2014

Distinguishing orbital angular momenta and topological charge in optical vortex beams

In this work we discuss how the classical orbital angular momentum (OAM) and topological charge (TC) of optical beams with arbitrary spatial phase profiles are related to the local winding density. An analysis for optical vortices (OV) with non-cylindrical symmetry is presented and it is experimentally shown for the first time that OAM and TC may have different values. The new approach also provides a systematic way to determine the uncertainties in measurements of TC and OAM of arbitrary OV.

physics.optics↗
arXiv2007

Random Fiber Laser

We investigate the effects of two dimensional confinement on the lasing properties of a classical random laser system operating in the incoherent feedback (diffusive) regime. A suspension of 250nm rutile (TiO2) particles in a Rhodamine 6G solution was inserted into the hollow core of a photonic crystal fiber (PCF) generating the first random fiber laser and a novel quasi-one-dimensional RL geometry. Comparison with similar systems in bulk format shows that the random fiber laser presents an efficiency that is at least two orders of magnitude higher.

physics.optics↗