We present an efficient and easily implemented approach for creating stable electrocatalytically active nanocomposites based on polyaniline (PANI) with metal NPs. The approach combines in situ synthesis of polyaniline followed by laser-induced deposition (LID) of Ag, Pt, and AgPt NPs. The observed peculiarity of LID of PANI is the role of the substrate during the formation of multi-metallic nanoparticles (MNP). This allows us to solve the problem of losing catalytically active particles from the electrode's surface in electrochemical use. The synthesized PANI/Ag, PANI/Pt, and PANI/AgPt composites were studied with different techniques, such as SEM, EDX, Raman spectroscopy, and XPS. These suggested a mechanism for the formation of MNP on PANI. The MNP-PANI interaction was demonstrated, and the functionality of the nanocomposites was studied through the electrocatalysis of the hydrogen evolution reaction. The PANI/AgPt nanocomposites demonstrated both the best activity and the most stable metal component in this process. The suggested approach can be considered as universal, since it can be extended to the creation of electrocatalytically active nanocomposites with various mono- and multi-metallic NPs.
Optimizing the generation of polarization squeezed light in nonlinear optical fibers driven by femtosecond pulses
A. Andrianov V,
Nikolay Kalinin,
A. A. Sorokin,
E. A. Anashkina,
Luis Sanchez-Soto,
J. F. Corney,
Gerd Leuchs
OPTICS EXPRESS
31
(1)
765-773
(2022)
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| PDF
Bright squeezed light can be generated in optical fibers utilizing the Kerr effect for ultrashort laser pulses. However, pulse propagation in a fiber is subject to nonconservative effects that deteriorate the squeezing. Here, we analyze two-mode polarization squeezing, which is SU(2)-invariant, robust against technical perturbations, and can be generated in a polarization-maintaining fiber. We perform a rigorous numerical optimization of the process and the pulse parameters using our advanced model of quantum pulse evolution in the fiber that includes various nonconservative effects and real fiber data. Numerical results are consistent with experimental results. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
Anticaustics in a Fabry-Perot interferometer
Luis Sanchez-Soto,
Juan J. Monzon,
Gerd Leuchs
JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND
VISION
39
(12)
C74-C78
(2022)
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We address the response of a Fabry-Perot interferometer to a monochromatic point source. We calculate the anti -caustics (that is, the virtual wavefronts of null path difference) resulting from the successive internal reflections occurring in the system. They turn out to be a family of ellipsoids (or hyperboloids) of revolution, which allows us to reinterpret the operation of the Fabry-Perot interferometer from a geometrical point of view that facilitates comparison with other apparently disparate arrangements, such as Young's double slit. (c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
Towards Quantum Noise Squeezing for 2-Micron Light with Tellurite and Chalcogenide Fibers with Large Kerr Nonlinearity
Arseny A. Sorokin,
Gerd Leuchs,
Joel F. Corney,
Nikolay Kalinin,
Elena A. Anashkina,
Alexey Andrianov V
Squeezed light-nonclassical multiphoton states with fluctuations in one of the quadrature field components below the vacuum level-has found applications in quantum light spectroscopy, quantum telecommunications, quantum computing, precision quantum metrology, detecting gravitational waves, and biological measurements. At present, quantum noise squeezing with optical fiber systems operating in the range near 1.5 mu m has been mastered relatively well, but there are no fiber sources of nonclassical squeezed light beyond this range. Silica fibers are not suitable for strong noise suppression for 2 mu m continuous-wave (CW) light since their losses dramatically deteriorate the squeezed state of required lengths longer than 100 m. We propose the generation multiphoton states of 2-micron 10-W class CW light with squeezed quantum fluctuations stronger than -15 dB in chalcogenide and tellurite soft glass fibers with large Kerr nonlinearities. Using a realistic theoretical model, we numerically study squeezing for 2-micron light in step-index soft glass fibers by taking into account Kerr nonlinearity, distributed losses, and inelastic light scattering processes. Quantum noise squeezing stronger than -20 dB is numerically attained for a customized As2Se3 fibers with realistic parameters for the optimal fiber lengths shorter than 1 m. For commercial As2S3 and customized tellurite glass fibers, the expected squeezing in the -20--15 dB range can be reached for fiber lengths of the order of 1 m.
Formation of Non-Classical Multiphoton States of Light with Squeezed Quantum Fluctuations in Bismuth-Modified Tellurite Glass Fibers
A. A. Sorokin,
V. V. Dorofeev,
S. E. Motorin,
I Lyashuk,
J. Porins,
Gerd Leuchs,
V Bobrovs
OPTICS AND SPECTROSCOPY
130
(2)
102-107
(2022)
| Journal
An optical fiber with a high Kerr nonlinearity coefficient has been proposed and manufactured from bismuth-modified tellurite glass for creation of non-classical multiphoton states of light. Specifically, we have proposed to use these fibers to squeeze the quantum fluctuations of one of the quadratures of light in the 20 W signal significantly below -10 dB compared to the standard quantum noise limit, which is important for various practical applications. Using numerical simulation based on the stochastic nonlinear Schrodinger equation, we have demonstrated noise squeezing stronger than -16 dB at tellurite fiber lengths of 6-14 m, while in squeezing of -14 dB is expected in silica glass fibers having lengths of 120-300 m. Analytical formulas were used to analyze the physical factors that limit the achievable squeezing.
Vacuum breakdown in magnetic dipole wave by 10-PW class lasers
E. S. Efimenko,
A. Bashinov V,
A. A. Muraviev,
V. D. Volokitin,
I. B. Meyerov,
Gerd Leuchs,
A. M. Sergeev,
A. Kim V
The vacuum breakdown by 10-PW-class lasers is studied in the optimal configuration of laser beams in the form of an m-dipole wave, which maximizes the magnetic field. Using 3D PIC simulations we calculated the threshold of vacuum breakdown, which is about 10 PW. We examined in detail the dynamics of particles and identified particle trajectories which contribute the most to vacuum breakdown in such highly inhomogeneous fields. We analyzed the dynamics of the electron-positron plasma distribution on the avalanche stage. It is shown that the forming plasma structures represent concentric toroidal layers and the interplay between particle ensembles from different spatial regions favors vacuum breakdown. Based on the angular distribution of charged particles and gamma photons a way to experimentally identify the process of vacuum breakdown is proposed.
Single-Step Process for Titanium Surface Micro- and Nano-Structuring and In Situ Silver Nanoparticles Formation by Ultra-Short Laser Patterning
Dante Maria Aceti,
Emil Filipov,
Liliya Angelova,
Lamborghini Sotelo,
Tommaso Fontanot,
Peyman Yousefi,
Silke Christiansen,
Gerd Leuchs,
Stanislav Stanimirov, et al.
Ultra-short laser (USL)-induced surface structuring combined with nanoparticles synthesis by multiphoton photoreduction represents a novel single-step approach for commercially pure titanium (cp-Ti) surface enhancement. Such a combination leads to the formation of distinct topographical features covered by nanoparticles. The USL processing of cp-Ti in an aqueous solution of silver nitrate (AgNO3) induces the formation of micron-sized spikes surmounted by silver nanoparticles (AgNPs). The proposed approach combines the structuring and oxidation of the Ti surface and the synthesis of AgNPs in a one-step process, without the use of additional chemicals or a complex apparatus. Such a process is easy to implement, versatile and sustainable compared to alternative methodologies capable of obtaining comparable results. Antimicrobial surfaces on medical devices (e.g., surgical tools or implants), for which titanium is widely used, can be realized due to the simultaneous presence of AgNPs and micro/nano-structured surface topography. The processed surfaces were examined by means of a scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) and Raman spectroscopy. The surface morphology and the oxidation, quality and quantity of AgNPs were analyzed in relation to process parameters (laser scanning speed and AgNO3 concentration), as well as the effect of AgNPs on the Raman signal of Titanium oxide.
Particle trajectories, gamma-ray emission, and anomalous radiative trapping effects in magnetic dipole wave
A. Bashinov V,
E. S. Efimenko,
A. A. Muraviev,
V. D. Volokitin,
I. B. Meyerov,
Gerd Leuchs,
A. M. Sergeev,
A. Kim V
In studies of interaction of matter with laser fields of extreme intensity there are two limiting cases of a multibeam setup maximizing either the electric field or the magnetic field. In this work attention is paid to the optimal configuration of laser beams in the form of an m-dipole wave, which maximizes the magnetic field. We consider in such highly inhomogeneous fields the advantages and specific features of laser-matter interaction, which stem from individual particle trajectories that are strongly affected by gamma photon emission. It is shown that in this field mode qualitatively different scenarios of particle dynamics take place in comparison with the mode that maximizes the electric field. A detailed map of possible regimes of particle motion (ponderomotive trapping, normal radiative trapping, radial, and axial anomalous radiative trapping), as well as angular and energy distributions of particles and gamma photons, is obtained in a wide range of laser powers up to 300 PW, and it reveals signatures of radiation losses experimentally detectable even with subpetawatt lasers.
Extreme Concentration and Nanoscale Interaction of Light
Gerd Leuchs,
Alexey Andrianov V,
Elena A. Anashkina,
Alina A. Manshina,
Peter Banzer,
Markus Sondermann
ACS PHOTONICS
9
(6)
1842-1851
(2022)
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Concentrating light strongly calls for appropriate polarization patterns of the focused light beam and for up to a full 4 pi solid angle geometry. Focusing on the extreme requires efficient coupling to nanostructures of one kind or another via cylindrical vector beams having such patterns, the details of which depend on the geometry and property of the respective nanostructure. Cylindrical vector beams can not only be used to study a nanostructure, but also vice versa. Closely related is the discussion of topics such as the ultimate diffraction limit, a resonant field enhancement near nanoscopic absorbers, as well as speculations about nonresonant field enhancement, which, if it exists, might be relevant to pair production in vacuum. These cases do require further rigorous simulations and more decisive experiments. While there is a wide diversity of scenarios, there are also conceptually very different models offering helpful intuitive pictures despite this diversity.
Quantumness beyond entanglement: The case of symmetric states
Aaron Z. Goldberg,
Markus Grassl,
Gerd Leuchs,
Luis L. Sanchez-Soto
PHYSICAL REVIEW A
105
(2)
022433
(2022)
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Nowadays, it is accepted that truly quantum correlations can exist even in the absence of entanglement. For the case of symmetric states, a physically trivial unitary transformation can alter a state from entangled to separable, and vice versa. We propose to certify the presence of quantumness via an average of a state's bipartite entanglement properties over all physically relevant modal decompositions. We investigate extremal states for such a measure: SU(2)-coherent states possess the least quantumness, whereas the opposite extreme is inhabited by states with maximally spread Majorana constellations.
Quantum Noise Squeezing for Optical Signals in Zinc-Tellurite Fibers
A. A. Sorokin,
V. V. Dorofeev,
S. E. Motorin,
Gerd Leuchs
BULLETIN OF THE LEBEDEV PHYSICS INSTITUTE
48
(12)
390-394
(2022)
| Journal
Nonclassical multiphoton states of light with squeezed quantum fluctuations are in demand for various ultrahigh-accuracy measurements. In this study, we propose to use fiber of bismuth-modified zinc-tellurite glass with high Kerr nonlinearity to squeeze quantum noise of optical signals. We experimentally fabricated such fiber and, using numerical simulation of the nonlinear evolution of cw laser signal taking into account fiber characteristics for optimum parameters, theoretically demonstrated noise squeezing better than -15 dB.
From polarization multipoles to higher-order coherences
Aaron Z. Goldberg,
Andrei B. Klimov,
Hubert DeGuise,
Gerd Leuchs,
Girish S. Agarwal,
Luis Sanchez-Soto
We demonstrate that the multipoles associated with the density matrix are truly observable quantities that can be unambiguously determined from intensity moments. Given their correct transformation properties, these multipoles are the natural variables to deal with a number of problems in the quantum domain. In the case of polarization, the moments are measured after the light has passed through two quarter-wave plates, one half-wave plate, and a polarizing beam splitter for specific values of the angles of the wave plates. For more general two-mode problems, equivalent measurements can be performed. (C) 2022 Optical Society of America
Lenslet array-free efficient coherent combining of broadband pulses at the output of a multicore fiber with a square core grid
Nikolay Kalinin,
Elena A. Anashkina,
Gerd Leuchs,
Alexey Andrianov V
OPTICS EXPRESS
30
(2)
1013-1020
(2022)
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| PDF
An efficient optical scheme for coherent combining of radiation from the output of a multicore fiber (MCF) with a square array of cores in the out-of-phase supermode is proposed. The scheme uses only simple optical elements and is suitable for an arbitrary number of MCF cores. In a proof-of-concept experiment broadband pulses transmitted through a 25-core fiber were combined with 81% efficiency and good beam quality. In numerical modeling a close to unity efficiency is obtained for a large number of cores. The proposed scheme can be used in a reverse direction for efficient beam splitting and launching the out-of-phase supermode into the MCF. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement
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