- On the maximization of entropy in the process of thermalization of highly multimode nonlinear beams
We present a direct experimental confirmation of the maximization of entropy which accompanies the thermalizationof a highly multimode light beam, upon its nonlinear propagation in standard graded-index (GRIN) optical fibers. The spatial beam self-cleaning effect consists of the nonlinear transformation Read More … - Observation of Visible Upconversion Luminescence of Soft Glass Multimode Fibers
This research investigates the visible upconversion luminescence which is induced bymultiphoton absorption of soft glass fiber defects. The study of this phenomenon has thus far beenrestricted to standard silica fibers. We observed the emission of green and cyan light as Read More … - Multidimensional localized states in externally driven Kerr cavities with a parabolic spatiotemporal potential: A dimensional connection
In this work, we study the bifurcation structures and the stability of multidimensional localized states withincoherently driven Kerr optical cavities with parabolic potentials in 1D, 2D, and 3D systems. Based on symmetricconsiderations, we transform higher-dimensional models into a single 1D Read More … - Calorimetry of Photon Gases in Nonlinear Multimode Optical Fibers
Recent studies have shown that light propagating in a nonlinear, highly multimode system canthermalize in a manner totally analogous to that encountered in traditional statistical mechanics. At thermalequilibrium, the system’s entropy is at a maximum, in full accord with the Read More … - Purequarticthree-dimensionalspatiotemporalKerrsolitons
We analyze the formation of three-dimensional spatiotemporal solitons in waveguides with a parabolic refractive index profile and pure quartic chromatic dispersion. We show, by applying both variational approaches and full three-dimensional numerical simulations, that fourth-order dispersion has a positive impact Read More … - Robust Three-Dimensional High-Order Solitons and Breathers in Driven Dissipative Systems: A Kerr Cavity Realization
We present a general approach to excite robust dissipative three-dimensional and high-order solitons and breathers in passively driven nonlinear cavities. Our findings are illustrated in the paradigmatic example provided by an optical Kerr cavity with diffraction and anomalous dispersion, with Read More … - Soft glass optical fiber characterization with X-ray computed microtomography
The high loss due to the presence of strong phonon resonances makes silica fibers unfit for applications in the mid-infrared spectral range. This has led to the development of specialty optical fibers, based on novel materials and manufacturing techniques. In Read More … - Statistics of modal condensation in nonlinear multimode fibers
Optical pulses traveling through multimode optical fibers encounter the influence of both linear disturbances and nonlinearity, resulting in a complex and chaotic redistribution of power among different modes. In our research, we explore the phenomenon where multimode fibers reach stable Read More … - Modal phase-locking in multimode nonlinear optical fibers
Spatial beam self-cleaning, a manifestation of the Kerr effect in graded-index multimode fibers, involves a nonlinear transfer of power among modes, which leads to robust bell-shaped output beams. The resulting mode power distribution can be described by statistical mechanics arguments. Read More … - Multimode Optical Fiber Beam-By-Beam Cleanup
We introduce and experimentally demonstrate the concept of all-optical beam switching in graded-index multimode optical fibers. Nonlinear coupling between orthogonally polarized seed and signal beams permits to control the spatial beam quality at the fiber output. Remarkably, we show that Read More … - Dissipative Kerr solitons, breathers, and chimera states in coherently driven passive cavities with parabolic potential
We analyze the stability and dynamics of dissipative Kerr solitons (DKSs) in the presence of a parabolic potential. This potential stabilizes oscillatory and chaotic regimes, favoring the generation of static DKSs. Furthermore, the potential induces the emergence of new dissipative Read More … - X-ray computed µ-tomography for the characterization of optical fibers
In spite of their ubiquitous applications, the characterization of glass fibers by meansof all-optical techniques is still facing some limitations. Recently, X-ray absorption has beenproposed as a method for visualizing the inner structure of both standard and microstructure opticalfibers. Here, Read More … - Fast dispersion tailoring of multimode photonic crystal resonators
We introduce a numerical procedure which permits us to drastically accelerate the design of multimodephotonic crystal resonators. Specifically, we demonstrate that the optical response of an important class of suchnanoscale structures is reproduced accurately by a simple, one-dimensional model within Read More … - Roadmap on multimode photonics
Multimode devices and components have attracted considerable attention in the last years, and different research topics and themes have emerged very recently. The multimodality can be seen as an additional degree of freedom in designing devices, thus allowing for the Read More … - Characterization of Multimode Soliton Self-Frequency Shift
Optical solitons in multimode fibers exhibit complex dynamics, and peculiar characteristics in terms of pulse durationand energy, which distinguish them from the single-mode counterpart. We propose a theory for Raman-induced soliton selffrequency shift in multimode fibers, that is compared against Read More … - Multimode Photonics Workshop 2022
Discover how controlling self-organization phenomena in multimode photonics systems is the keystone for the next generation of internet and computing technologies. 22 – 25 August 2022 At Department of Information Engineering, Electronics, and Telecommunications, Sapienza University of Rome, Via Eudossiana Read More … - Thermalization of orbital angular momentum beams in multimode optical fibers
We report on the thermalization of light carrying orbital angular momentum in multimode optical fibers, induced by nonlinear intermodal interactions. A generalized Rayleigh-Jeans distribution of asymptotic mode composition is obtained, based on the conservation of the angular momentum. We confirm Read More … - Multimode soliton collisions in graded-index optical fibers
In this work, we unveil the unique complex dynamics of multimode soliton interactions in graded-index optical fibers through simulations and experiments. By generating two multimode solitons from the fission of an input femtosecond pulse, we examine the evolution of their Read More … - Statistical mechanics of beam self-cleaning in GRIN multimode optical fibers
Since its first demonstration in graded-index multimode fibers, spatial beam self-cleaning has attracted a growing research interest. It allows for the propagation of beams with a bell-shaped spatial profile, thus enabling the use of multimode fibers for several applications, from Read More … - Multiphoton ionization of standard optical fibers
Atoms ionization by the simultaneous absorption of multiple photons has found applications in fiber optics, where it leads to unique nonlinear phenomena. To date, studies of the ionization regime have been limited to gas-filled hollow-core fibers. Here, we investigate multiphoton Read More … - Helical plasma filaments from the self-channeling of intense femtosecond laser pulses in optical fibers
We experimentally and numerically study the ignition of helical-shaped plasma filaments in standard optical fibers. Femtosecond pulses with megawatt peak power with proper off-axis and tilted coupling in the fiber core produce plasma skew rays. These last for distances as Read More … - Femtosecond nonlinear losses in multimode optical fibers
Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams, coupled with novel nonlinear optics-based applications. However, optical fiber breakdown occurs when beam intensities exceed a certain critical value. Optical breakdown associated with irreversible Read More … - Multimode solitons in step-index fibers
We experimentally generate multimode solitons in step-index fibers, where nonlinearity compensates for both chromatic and modal dispersion. These solitons are subject to Raman self-frequency shift, and their energy is gradually transfered to the fundamental fiber mode. We compare multimode soliton Read More … - Spatiotemporal beam self‑cleaning for high‑resolution nonlinear fuorescence imaging with multimode fber
Beam self-cleaning (BSC) in graded-index (GRIN) multimode fbers (MMFs) has been recently reported by diferent research groups. Driven by the interplay between Kerr efect and beam self-imaging, BSC counteracts random mode coupling, and forces laser beams to recover a quasi-single Read More … - Conditions for walk-off soliton generation in a multimode fiber
It has been recently demonstrated that multimode solitons are unstable objects which evolve, in the range of hundreds of nonlinearity lengths, into stable single-mode solitons carried by the fundamental mode. We show experimentally and by numerical simulations that femtosecond multimode Read More … - Experimental observation of self-imaging in SMF-28 optical fibers
Spatial self-imaging, consisting of the periodic replication of the optical transverse beam profile along the propagation direction, can be achieved in guided wave systems when all excited modes interfere in phase. We exploited material defects photoluminescence for directly visualizing self-imaging Read More … - 3D time-domain beam mapping for studying nonlinear dynamics in multimode optical fibers
Characterization of the complex spatiotemporal dynamics of optical beam propagation in nonlinear multimode fibers requires the development of advanced measurement methods, capable of capturing the real-time evolution of beam images. We present a new space–time mapping technique, permitting the direct Read More … - Singlemode spatiotemporal soliton attractor
January 29th, 2021 Experimental and numerical studies of spatiotemporal femtosecond soliton propagation over up to 1 km spans of parabolic graded-index (GRIN) fibers reveal that initial multimode soliton pulses naturally and irreversibly evolve into a singlemode soliton. This is carried Read More … - Managing Self-Phase Modulation in Pseudolinear Optical Transmission Systems
January 13th, 2021 We propose a new semi-analytical model, describing the bandwidth evolution of pulses propagating in dispersion managed (DM) transmission systems using multimodal graded-index fibers (GRIN) with parabolic index. The model also applies to monomodal fiber DM systems, representing Read More … - Giving light a new twist: rainbow spiral emission
October 1st, 2020 We demonstrate a new practical approach for generating multicolour spiral-shaped beams. It makes use of a standard silica optical fibre, combined with a titled input laser beam. The resulting breaking of the fibre axial symmetry leads to Read More … - Upconversion luminescence in optical fibers
September 25th, 2020 We experimentally demonstrate a previously unforeseen nonlinear effect in optical fibers: up-conversion luminescence generation excited by multiphoton absorption of femtosecond infrared pulses. We directly estimate the average number of photons involved in the up-conversion process, by varying Read More … - Distributed Kerr Lens Mode-Locking in Multimode Fiber Laser
July 20th, 2020 We introduce a mechanism of stable spatiotemporal soliton formation in a multimode fiber laser. This is based on spatially graded dissipation, leading to distributed Kerr-lens mode locking. Our analysis involves solutions of a generalized dissipative Gross-Pitaevskii equation. Read More … - Nonlinear beam self-imaging
May 14th, 2020 Beam self-imaging in nonlinear graded-index multimode optical fibers is of interest for many applications, such as implementing a fast saturable absorber mechanism in fiber lasers via multimode interference. We obtain a new exact solution for the nonlinear Read More … - High-energy soliton fission
May 2nd, 2020 The process of high-energy soliton fission is experimentally and numerically investigated in a graded-index multimode fiber. Fission dynamics is analyzed by comparing numerical observations and simulations. A novel regime is observed, where solitons produced by the fission Read More … - Online school on: Machine learning photonics
Online school on: Machine learning photonics Lake Como School of Advanced Studies Dates: March 15-19, 2021 The school brings together experts in emerging photonic technologies, machine learning techniques, and fundamental physics who will share with young researchers their knowledge and Read More …
Department of Information Engineering, Electronics and Telecommunications