Showing papers by "Aristide Dogariu published in 2021"
TL;DR: In this article, the authors proposed a technique to measure the value of the topological charge of a vortex beam obscured in the randomly scattered light, which is applicable to a dynamic diffuser.
Abstract: Encoding information using the topological charge of vortex beams has been proposed for optical communications. The conservation of the topological charge on propagation and the detection of the topological charge by a receiver are significant in these applications and have been well established in free-space. However, when vortex beams enter a diffuser, the wavefront is distorted, leading to a challenge in the conservation and detection of the topological charge. Here, we present a technique to measure the value of the topological charge of a vortex beam obscured in the randomly scattered light. The results of the numerical simulations and experiments are presented and are in good agreement. In particular, only a single-shot measurement is required to detect the topological charge of vortex beams, indicating that the method is applicable to a dynamic diffuser.
8 citations
4 citations
09 May 2021
TL;DR: In this article, a sensor for interrogating dynamic propagation environments for real-time detection of time-varying beams with OAM is introduced, where a rotating variable fog distribution is created and sensed for induced changes in OAM.
Abstract: This paper introduces a sensor for interrogating dynamic propagation environments for real-time detection of time-varying beams with OAM. As an example, a rotating variable fog distribution is created and sensed for induced changes in OAM.
3 citations
TL;DR: In this paper, the role of the helicity in the coupling between electrodynamic fields and vibrations was examined, and a group of modes of coherent oscillations were identified that give rise to a strong and delocalized response, selectivity in frequency and a typical interaction range.
Abstract: Helical structures like alpha helices, DNA, and microtubules have profound importance in biology. It has been suggested that these periodic arrangements of constituent units could support collective excitations similarly to crystalline solids. Here, we examine the interaction between such constructs and oscillating dipoles, and evaluate the role of the helicity in the coupling between electrodynamic fields and vibrations. Based on vibrational and eigenfunction analyses we identify a group of modes of coherent oscillations that give rise to a strong and delocalized response, selectivity in frequency, and a typical interaction range. To describe the field scattering due to the structure vibrations we consider an anisotropic permittivity with a helical periodicity, which applies to all vibration types and close dipole locations. The type of resonances identified here may help explain the role of electrodynamic fields in the diverse functionality of cytoskeletal microtubules in the cellular environment.
3 citations
Posted Content•
TL;DR: In this paper, the authors examined quantitatively the degradation of perfect optical vortex beams after their interaction with localized random media and developed an analytical model that describes how the spatial correlation length and the phase variance of the disturbance affect the phase distribution across the vortex beams.
Abstract: Optical vortex beams have been under considerable attention recently due to their demonstrated potential for applications ranging from optical communication to particle trapping. Practical problems related to the dependence between their phase structure and the physical size have been addressed by introducing the concept of perfect optical vortex beams. Propagation of these structured beams through different levels of disturbances is critical for their uses. For the first time, we examine quantitatively the degradation of perfect optical vortex beams after their interaction with localized random media. We developed an analytical model that describes how the spatial correlation length and the phase variance of the disturbance affect the phase distribution across the vortex beams. This allows to ascertain the regimes of randomness where the beams maintain the memory of their initial vorticity. Systematic numerical simulations and controlled experiments demonstrate the extent of this memory effect for beams with different vorticity indices.
2 citations
TL;DR: In this article, an optical vortex beam can dynamically control the spatial density of microscopic particles along the direction of its propagation, which can be beneficial for applications such as path clearing and mass transportation.
Abstract: Optical manipulation of colloidal systems is of high interest for both fundamental studies and practical applications. It has been shown that optically induced thermophoresis and nonlinear interactions can significantly affect the properties of dense colloidal media. However, macroscopic scale phenomena can also be generated at thermal equilibrium. Here, we demonstrate that steady-state variations of particle density can be created over large, three-dimensional regions by appropriately structured external optical fields. We prove analytically and experimentally that an optical vortex beam can dynamically control the spatial density of microscopic particles along the direction of its propagation. We show that these artificial steady-states can be generated at will and can be maintained indefinitely, which can be beneficial for applications such as path clearing and mass transportation.
1 citations
01 Jul 2021
TL;DR: In this article, the authors investigate the applications of Higher Order Bessel Beams with temporal modulation of Orbital Angular Momentum (OAM) for maritime applications, including the creation and detection of HOBBIT beams at unprecedented time scales and power densities.
Abstract: In this paper, we investigate the applications of Higher Order Bessel Beams with temporal modulation of Orbital Angular Momentum (OAM) for maritime applications. Examples include the creation and detection of HOBBIT beams at unprecedented time scales and power densities. Results are also presented for sensing of rotating fog clouds and nonlinear interactions in water.
09 May 2021
TL;DR: In this article, the authors used vibrational and eigenfunction analyses to show that phonons in a helical structure exhibit delocalized response and selectivity in frequency, and examined the eigenpermittivities and density of electromagnetic states in proximity to such a structure.
Abstract: Using a vibrational and eigenfunction analyses we show that phonons in a helical structure exhibit delocalized response and selectivity in frequency. We also examine the eigenpermittivities and density of electromagnetic states in proximity to such a structure.
09 May 2021
TL;DR: The authors showed that vortex beams maintain a certain memory of initial properties upon interaction with different randomly scattering media, and described the extent of this memory in relation to variance and spatial correlation of randomness.
Abstract: We demonstrate that, upon interaction with different randomly scattering media, vortex beams maintain a certain memory of initial properties. We describe the extent of this memory in relation to variance and spatial correlation of randomness
09 May 2021
TL;DR: In this paper, the authors demonstrate the steady-state reduction of optical density along the path of vortex beams along with adjustable properties of the external field control the temporal and spatial scales of this radial transport of mass.
Abstract: We demonstrate the steady-state reduction of optical density along the path of vortex beams. The adjustable properties of the external field control the temporal and spatial scales of this radial transport of mass.
09 May 2021
TL;DR: In this paper, the authors demonstrate that intensity statistics is nonstationary in diffusive regimes of waves in reflection from random media and propose a statistical model based on recurrent scattering and near field coupling.
Abstract: We demonstrate that intensity statistics is nonstationary in diffusive regimes of waves in reflection from random media. A statistical model based on recurrent scattering and near field coupling is proposed and confirmed experimentally.
01 Jul 2021
TL;DR: In this article, a statistical analysis of the phase of random fields generated by scattering of Laguerre-Gauss beams is presented, where the standard deviation of the speckle phase is studied using the formalism of equiprobability density ellipses.
Abstract: We present a statistical analysis of the phase of random fields generated by scattering of Laguerre-Gauss beams. The standard deviation of the speckle phase is studied using the formalism of equiprobability density ellipses.
09 May 2021
TL;DR: In this paper, an analytical model for 3D spatial cross-correlations in speckles fields generated by scattering of structured beams is developed, and specific properties identified for different types of optical vortices can guide their use in remote sensing applications.
Abstract: We developed an analytical model for 3D spatial cross-correlations in speckles fields generated by scattering of structured beams. Specific properties identified for different types of optical vortices can guide their use in remote sensing applications.
19 Jul 2021
TL;DR: In this article, the authors provide a quantitative description of the measurable vorticity as a function of variance and spatial correlation properties of distorting media. And they show that the properties of vortex beams are significantly affected upon interaction with random phase screens.
Abstract: Properties of vortex beams are significantly affected upon interaction with random phase screens. We provide a quantitative description of the measurable vorticity as a function of variance and spatial correlation properties of distorting media.
01 Jul 2021
TL;DR: In this paper, a general model for the three-dimensional spatial coherence function of speckle fields generated by scattering of vortex beams was developed, which describes the correlation function along transversal and longitudinal directions.
Abstract: We developed a general model for the three-dimensional spatial coherence function of speckle fields generated by scattering of vortex beams. The model describes the correlation function along transversal and longitudinal directions, and provides for means for controlling the coherence function via vortex parameters.
TL;DR: In this article, an analytical model for the 3D spatial coherence function of speckle fields generated by scattering of vortex and perfect optical vortex beams is developed. But the model is general and does not consider the temporal distribution of the coherence along both the transversal and longitudinal directions.
Abstract: We develop an analytical model for the 3D spatial coherence function of speckle fields generated by scattering of vortex and perfect optical vortex beams. The model is general and describes the spatial coherence along both the transversal and the longitudinal directions. We found that, on propagation, the 3D spatial coherence evolves differently for the different types of initially structured beams, which may affect their use in a variety of sensing applications.