arXiv subjects

Zeev Zalevsky

Publications and source records attributed to Zeev Zalevsky.

14 recordsLinked to original sources

arXiv2025

Decoding Orbital Angular Momentum in Turbid Tissue-like Scattering Medium via Fourier-Domain Deep Learning

Structured light beams carrying orbital angular momentum (OAM), such as Laguerre-Gaussian modes, are promising tools for high-capacity optical communications and advanced biomedical imaging. However, multiple scattering in turbid media distorts their phase and amplitude, complicating the retrieval of topological charge. We introduce VortexNet, a deep learning architecture that integrates an Angular Fourier Transform to explicitly extract rotational symmetries of OAM beams from experimentally acquired intensity and interference patterns. By transforming spatial information into the angular frequency domain, VortexNet isolates azimuthal features that persist despite scattering, enabling accurate topological charge classification even in complex optical environments. The results reveal that OAM-specific angular correlations can survive multiple scattering and be decoded through angular-domain learning. This establishes a new paradigm for structured-light analysis in complex medium, where deep learning enables the recovery of topological information beyond the reach of classical optics, paving the way for resilient photonic systems in communication, sensing, and imaging.

physics.optics↗

arXiv2025

Inferring scattering-type Scanning Near-Field Optical Microscopy Data from Atomic Force Microscopy Images

Optical nanoscopy is crucial in life and materials sciences, revealing subtle cellular processes and nanomaterial properties. Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) provides nanoscale resolution, relying on the interactions taking place between a laser beam, a sharp tip and the sample. The Atomic Force Microscope (AFM) is a fundamental part of an s-SNOM system, providing the necessary probe-sample feedback mechanisms for data acquisition. In this Letter, we demonstrate that s-SNOM data can be partially inferred from AFM images. We first show that a generative artificial intelligence (AI) model (pix2pix) can generate synthetic s-SNOM data from experimental AFM images. Second, we demonstrate that virtual s-SNOM data can be extrapolated from knowledge of the tip position and, consequently, from AFM signals. To this end, we introduce an analytical model that explains the mechanisms underlying AFM-to-s-SNOM image translation. These insights have the potential to be integrated into future physics-informed explainable AI models. The two proposed approaches generate pseudo s-SNOM data without direct optical measurements, significantly expanding access to optical nanoscopy through widely available AFM systems. This advancement holds great promise for reducing both time and costs associated with nanoscale imaging.

physics.optics↗

arXiv2025

Imaging artefacts in scattering-type scanning near field optical microscopy arising from optical diffraction effects and contrast-active sub-surface features

The scattering-type Scanning Near-Field Optical Microscope (s-SNOM) is acknowledged as an excellent tool to investigate the optical properties of different materials and biological samples at the nanoscale. In this study we show that s-SNOM data are susceptible to being affected by specific artefacts related to the light diffraction phenomena and to stray contributions from shallow buried, contrast-active, structures. We focus on discussing the diffraction contributions from sample edges, next to those corresponding to one- or two-dimensional periodic structures, and undesired contributions from shallow buried periodic features. Each scenario was examined individually through both experimental methods and simulations. Our experimental findings reveal that such artefacts affect not only s-SNOM images demodulated at the direct-current (DC) component and the fundamental frequency, but also images demodulated at higher harmonic frequencies. We show that image artefacts caused by diffraction resemble the undesirable effects caused by illumination with a laser beam of unstable intensity, and that buried features can yield s-SNOM signals that cannot be distinguished from those originating from the sample surface, in absence of prior knowledge of the sample structure. Performed simulations confirm these experimental findings. This work enhances the understanding of s-SNOM data and paves the way for new data acquisition and postprocessing methods that can enable next-generation s-SNOM imaging and spectroscopy with significantly enhanced signal-to-noise ratio and resolution.

physics.optics↗

arXiv2025

Resolution enhancement in quantitative phase microscopy: a review

Quantitative phase microscopy (QPM), a technique combining phase imaging and microscopy, enables visualization of the 3D topography in reflective samples, as well as the inner structure or refractive index distribution of transparent and translucent samples. Similar to other imaging modalities, QPM is constrained by the conflict between numerical aperture (NA) and field of view (FOV): an imaging system with a low NA has to be employed to maintain a large FOV. This fact severely limits the resolution in QPM up to being the illumination wavelength. Consequently, finer structures of samples cannot be resolved by using modest NA objectives in QPM. Aimed to that, many approaches, such as oblique illumination, structured illumination, and speckle illumination (just to cite a few), have been proposed to improve the spatial resolution (or the space bandwidth product) in phase microscopy by restricting other degrees of freedom (mostly time). This paper aims to provide an up to date review on the resolution enhancement approaches in QPM, discussing the pros and cons of each technique as well as the confusion on resolution definition claims on QPM and other coherent microscopy methods. Through this survey, we will review the most appealing and useful techniques for superresolution in coherent microscopy, working with and without lenses and with special attention to QPM.

physics.optics↗

arXiv2024

Emerging non-local quantum phenomena in a classical system of organo-metallic microparticles

The work investigates enantiomers of chiral organo-metallic particles that exhibit a collective memory effect. Under the influence of magnetic field millions of particles in solution form macroscopic shapes and when dispersed again at zero field they return to their original shape. The charge and magnetic behaviors of the particles are strongly dependent on the handedness of the chiral molecule in the hybrid organometallic compound. The microparticles forming the shaped structures are collectively coupled under the influence of long-range van der Waals exchange interactions which govern the collective macroscopic structure. There is striking evidence that the nonlocal quantum exchange interactions between particles persist up to a distance of 10 meters at temperatures above 00C. The forces which govern the collective memory effect and shape the macroscopic structure therefore allow to visualize quantum phenomena which extend the classical causality notion into an expanded nonlocal reality in which the quantum fields of the particles exist simultaneously at separated points in space. We propose that the observations are attributed to chiral electronic states dependent van der Waals interactions coupled to vacuum fluctuations.

physics.chem-ph↗

arXiv2023

Efficient Reduction of Casimir Forces by Self-assembled Bio-molecular Thin Films

Casimir forces, related to London-van der Waals forces, arise if the spectrum of electromagnetic fluctuations is restricted by boundaries. There is great interest both from fundamental science and technical applications to control these forces on the nano scale. Scientifically, the Casimir effect being the only known quantum vacuum effect manifesting between macroscopic objects, allows to investigate the poorly known physics of the vacuum. In this work, we experimentally investigate the influence of self-assembled molecular bio and organic thin films on the Casimir force between a plate and a sphere. We find that molecular thin films, despite being a mere few nanometers thick, reduce the Casimir force by up to 14%. To identify the molecular characteristics leading to this reduction, five different bio-molecular films with varying chemical and physical properties were investigated. Spectroscopic data reveal a broad absorption band whose presence can be attributed to the mixing of electronic states of the underlying gold layer and those of the molecular film due to charge rearrangement in the process of self-assembly. Using Lifshitz theory we calculate that the observed change in the Casimir force is consistent with the appearance of the new absorption band due to the formation of molecular layers. The desired Casimir force reduction can be tuned by stacking several monolayers, using a simple self-assembly technique in a solution. The molecules - each a few nanometers long - can penetrate small cavities and holes, and cover any surface with high efficiency. This process seems compatible with current methods in the production of micro-electromechanical systems (MEMS), which cannot be miniaturized beyond a certain size due to `stiction' caused by the Casimir effect. Our approach could therefore readily enable further miniaturization of these devices.

quant-ph↗

arXiv2023

Randomness assisted in-line holography with deep learning

We propose and demonstrate a holographic imaging scheme exploiting random illuminations for recording hologram and then applying numerical reconstruction and twin removal. We use an in-line holographic geometry to record the hologram in terms of the second-order correlation and apply the numerical approach to reconstruct the recorded hologram. The twin image issue of the in-line holographic scheme is resolved by an unsupervised deep learning(DL) based method using an auto-encoder scheme. This strategy helps to reconstruct high-quality quantitative images in comparison to the conventional holography where the hologram is recorded in the intensity rather than the second-order intensity correlation. Experimental results are presented for two objects, and a comparison of the reconstruction quality is given between the conventional inline holography and the one obtained with the proposed technique.

physics.optics↗

arXiv2022

Towards Augmenting Tip-Enhanced Nanoscopy with Optically Resolved Scanning Probe Tips

A thorough understanding of biological species and of emerging nanomaterials requires, among others, their in-depth characterization with optical techniques capable of nano-resolution. Nanoscopy techniques based on tip-enhanced optical effects have gained over the past years tremendous interest given their potential to probe various optical properties with resolutions depending on the size of a sharp probe interacting with focused light, irrespective of the illumination wavelength. Although their popularity and number of applications is rising, tip-enhanced nanoscopy techniques (TEN) still largely rely on probes that are not specifically developed for such applications, but for Atomic Force Microscopy. This cages their potential in many regards, e.g. in terms of signal-to-noise ratio, attainable image quality, or extent of applications. In this article we place first steps towards next-gen TEN, demonstrating the fabrication and modelling of specialized TEN probes with known optical properties. The proposed framework is highly flexible and can be easily adjusted to be of o benefit to various types of TEN techniques, for which probes with known optical properties could potentially enable faster and more accurate imaging via different routes, such as direct signal enhancement or novel signal modulation strategies. We consider that the reported development can pave the way for a vast number of novel TEN imaging protocols and applications, given the many advantages that it offers.

physics.optics↗

arXiv2022

Reconstructing complex field through opaque scattering layer with structured light illumination

The wavefront is scrambled when coherent light propagates through a random scattering medium and which makes direct use of the conventional optical methods ineffective. In this paper, we propose and demonstrate a structured light illumination for imaging through an opaque scattering layer. Proposed technique is reference free and capable to recover the complex field from intensities of the speckle patterns. This is realized by making use of the phase-shifting in the structured light illumination and applying spatial averaging of the speckle pattern in the intensity correlation measurement. An experimental design is presented and simulated results based on the experimental design are shown to demonstrate imaging of different complex-valued objects through scattering layer.

physics.optics↗

arXiv2021

Structured transmittance illumination coherence holography

The coherence holography offers an unconventional way to reconstruct the hologram where an incoherent light illumination is used for reconstruction purposes, and object encoded into the hologram is reconstructed as the distribution of the complex coherence function. Measurement of the coherence function usually requires an interferometric setup and array detectors. This paper presents an entirely new idea of reconstruction of the complex coherence function in the coherence holography without an interferometric setup. This is realized by structured pattern projections on the incoherent source structure and implementing measurement of the cross-covariance of the intensities by a single-pixel detector. This technique, named structured transmittance illumination coherence holography (STICH), helps to reconstruct the complex coherence from the intensity measurement in a single-pixel detector without an interferometric setup and also keeps advantages of the intensity correlations. A simple experimental setup is presented as a first step to realize the technique, and results based on the computer modeling of the experimental setup are presented to show validation of the idea.

physics.optics↗

arXiv2021

Coherent, super resolved radar beamforming using self-supervised learning

High resolution automotive radar sensors are required in order to meet the high bar of autonomous vehicles needs and regulations. However, current radar systems are limited in their angular resolution causing a technological gap. An industry and academic trend to improve angular resolution by increasing the number of physical channels, also increases system complexity, requires sensitive calibration processes, lowers robustness to hardware malfunctions and drives higher costs. We offer an alternative approach, named Radar signal Reconstruction using Self Supervision (R2-S2), which significantly improves the angular resolution of a given radar array without increasing the number of physical channels. R2-S2 is a family of algorithms which use a Deep Neural Network (DNN) with complex range-Doppler radar data as input and trained in a self-supervised method using a loss function which operates in multiple data representation spaces. Improvement of 4x in angular resolution was demonstrated using a real-world dataset collected in urban and highway environments during clear and rainy weather conditions.

eess.SP↗

arXiv2014

Space Quantization of Light Transmission by Strong Coupling of Plasmonic Cavity Modes with Photosynthetic Complexes

The interaction between molecules and surface plasmons in defined geometries can lead to new light mater hybrid states where light propagation is strongly influenced by molecular photon absorption. Their application range from lasing LEDs to controlling chemical reactions and are relevant in light harvesting. The coupling between the electromagnetic field and molecular excitations may also lead to macroscopic extended coherent states characterized by an increase in temporal and spatial coherency. In this respect, it is intriguing to explore the coherency of the hybrid system for molecules that possess highly efficient exciton energy transfer. Such a molecule, is the photosynthetic light harvesting complex photosystem I which has an extended antenna system dedicated for efficient light harvesting. In this work, we demonstrate space quantization of light transmission through a single slit in free standing Au film coated with several layers of PS I. A self assembly technique for multilayer fabrication is used, enabling fabrication of multilayers which leaves most of the hole vacant with only the surface and slit walls coated with molecules. When a broad band, non coherent white light source excites the cavity, a strong SQOL is observed which is attributed to molecular photon absorption that induces coherency in the plasmon cavity modes. The SQOL is accompanied by a 13 fold enhancement in the extraordinary optical transmission through the cavity. This work demonstrate the emergence of spatial coherency in a cavity strongly coupled to one of the most efficient energy transfer photosynthetic protein in nature and provides the path for engineering quantum electrodynamics by the vast diversity of electronic properties of biological macromolecules.

physics.optics↗

arXiv2010

Manipulating Multistage Interconnection Networks Using Fundamental Arrangements

Optimizing interconnection networks is a prime object in switching schemes. In this work the authors present a novel approach for obtaining a required channel arrangement in a multi-stage interconnection network, using a new concept - a fundamental arrangement. The fundamental arrangement is an initial N-1 stage switch arrangement that allows obtaining any required output channel arrangement given an input arrangement, using N/2 binary switches at each stage. The paper demonstrates how a fundamental arrangement can be achieved and how, once this is done, any required arrangement may be obtained within 2(N-1) steps.

cs.NI↗

arXiv2009

Influence of Ge nanocrystals and radiation defects on C-V characteristics in Si-MOS structures

Metal-Oxide-Semiconductor (MOS) structures containing 74Ge nanocrystals (NC-Ge) imbedded inside the SiO_2 layer were studied for their capacitance characterization. Ge atoms were introduced by implantation of 74Ge+ ions with energy of 150 keV into relatively thick (~640nm) amorphous SiO_2 films. The experimental characterization included room temperature measurements of capacitance-voltage (C-V) dependences at high frequencies (100 kHz and 1 MHz). Four groups of MOS structures have been studied: The 1st - "initial" samples, without Ge atoms (before ion implantation). The 2nd - "implanted" samples, after Ge+ ion implantation but before annealing, with randomly distributed Ge atoms within the struggle layer. The 3rd - samples after formation of Ge nanocrystals by means of annealing at 800 degree C ("NC-Ge" samples), and the 4th - "final" samples: NC-Ge samples that were subjected by an intensive neutron irradiation in a research nuclear reactor with the integral dose up to 10^20 neutrons/cm^2 followed by the annealing of radiation damage. It is shown that in "initial" samples, the C-V characteristics have a step-like form of "S-shape", which is typical for MOS structures in the case of high frequency. However, in "implanted" and "NC-Ge" samples, C-V characteristics have "U-shape" despite the high frequency operation, In addition, "NC-Ge" samples exhibit a large hysteresis which may indicate charge trapping at the NC-Ge. Combination of the "U-shape" and hysteresis characteristics allows us to suggest a novel 4-digits memory retention unit. "Final" samples indicate destruction of the observed peculiarities of C-V characteristics and recurrence to the C-V curve of "initial" samples.

cond-mat.mes-hall↗