Optical Memory and Neural Networks最新文献

We have theoretically and experimentally considered the four-parameter generalized structured beam, which can be either in the initial state of a Laguerre-Gaussian beam or a Hermite-Gaussian beam, or in both states simultaneously. In astigmatic transformations, these states can alternate with orbital angular momentum reaching double the radial number with a single topological charge. The astigmatic transformations of a spiral triangular beam containing a composition of higher-order Laguerre-Gaussian modes were also analyzed. We found that such dramatic transformations are controlled by the astigmatic Gouy phase. Moreover, it was revealed that the invariant of such astigmatic transformations is the sum of the squares of the orbital angular momentum and the cross-intensity moment, representing the total orbital angular momentum equal to the square of the initial OAM.

The paper presents a comparison study results on the heterostructure between TiS₃ and Porous Silicon with pure Porous Silicon optoelectronic properties for photonics applications. To do this, titanium trisulfide, Porous Silicon and a heterostructure between them were synthesized and investigated. The TiS₃/P–Si heterostructure-based photodetector demonstrated a significant performance enhancement over the pure P–Si device. Key results include an 8 to 10 fold increase in photoresponsivity (reaching up to ~190 A/W at 2 V bias, wavelength of 632.8 nm and 0.3 mW/cm² light power density), quantum efficiency (exceeding 37%), and detectivity (up to 2.26 × 10¹⁰ Jones). Furthermore, the heterostructure exhibited a much faster response time of 0.015 s compared to 0.169 s for the pure P–Si device. The results demonstrate the relevance of using heterostructures for the development of new generation photodetectors.

In this paper, we used a numerical model to study the diffraction of scalar beams reflected from surfaces with rectangular periodic relief. We qualitatively analyzed the evolution of phase singularities in vortex beams with single and double topological charges. The influence of the relief depends on its height and position relative to the beam axis. It was shown that the magnitude of distortions in the initial beam increased when the ratio of the depression to the overhang became smaller than the radius of the singular beam on the surface of the specimen under study, whose relief height did not exceed one-quarter of the wavelength.

In this work, we investigate the trajectories of Laguerre–Gaussian beam states on the Poincaré sphere under general astigmatic transformation. It is shown that rotating the cylindrical lens shifts the trajectory into a plane perpendicular to the sphere’s axis, resulting in a precessional motion that depends on the rotate angle and the beam’s orbital angular momentum. The results are useful for analyzing and controlling the phase properties of light in optical systems.

In this paper, we study the sharp focusing of hybrid-polarized optical vortices using the Richards-Wolf formalism. The defining feature of these beams is a polarization state that combines azimuthal and circular properties—in the cross section of such a beam, depending on the azimuthal angle, the polarization changes from circular to azimuthal and back to circular. It is demonstrated theoretically and numerically that, although the total intensity forms a symmetric ring, the longitudinal component of the Poynting vector (P_z) exhibits a pronounced azimuthal asymmetry, indicating an asymmetric energy flow in the focal region. Central symmetry in the energy flux is a direct consequence of the hybrid polarization under sharp focusing, contrasting sharply with symmetric P_z distributions of uniformly or cylindrically polarized vortices.

To date, many different types and modifications of axicons (refractive, diffractive, micro- and meta-axicons) have been proposed, providing a wide range of functionality from generating laser beams extended along the optical axis to forming vortex and annular beams. This diversity of axicons arose with the development of existing and new approaches to calculating optical elements in response to the expansion of their application areas in optical manipulation, tight focusing, polarization transforming, materials processing, plasma channel formation, optical imaging, optical microscopy, and others. This review is devoted to a brief discussion of the various types of modern axicons and their applications.

This work presents the development of software for analyzing data obtained from simulations of laser radiation diffraction on micro-axicons, considering alignment errors such as displacement and tilt of the optical element relative to the incident beam. When modeling the axicon as a thin optical element, the tilt was simulated by introducing wavefront aberrations into the incident beam, specifically astigmatism and coma. A convolutional neural network was developed and trained to classify the resulting diffraction patterns, demonstrating high accuracy in identifying the type of aberration. The trained model achieved recognition accuracies of 100, 97.9, and 95.9% in three separate experiments. These experiments differed in the type of input data provided to the neural network: only intensity distributions, intensity combined with phase information, and intensity with defocused images, respectively. The results demonstrate that incorporating phase or additional spatial information significantly improves classification accuracy compared to intensity-only data. Even in the least accurate case (95.9%), the model shows strong generalization ability, making the proposed approach suitable for practical applications in optical diagnostics.

Various bends type of photonic crystal waveguides (by 120°, 60° and 45°) is designed in this paper using various deterministic optimization methods (coordinate descent method, Hook-Jeeves method and gradient descent). Application of zero-order optimization methods (coordinate descent and Hook-Jeeves) to bends by 120°, 60° on a crystal with a hexagonal lattice and air holes in the silicon layer made it possible to reduce the computation time by an average of 16 times compared to the genetic algorithm. The application of gradient descent to the design of a 45° bend on a crystal with a square lattice and silicon rods in air made it possible to achieve an increase in efficiency from 10 to 99%, and the number of calls to the target function during the algorithm’s operation is significantly lower compared to the genetic algorithm. Particular attention is paid to the consideration of the “partial search” method. Using the example of a photonic crystal waveguide bending by 120°, it is shown that the element designed by this method is characterized by radiation transmission practically without losses, while the computational complexity of the calculation is 1.5 times less than that of the genetic algorithm.

A method for estimating the relative position and orientation of a camera from corresponding image points is presented, in which the translation is eliminated from the optimization while the rotation is estimated using a spectral criterion based on the consistency of epipolar plane normals. For each point pair, a symmetric rank-1 matrix is constructed from the cross product of normalized bearing directions, and the smallest eigenvalue of the sum of these matrices is minimized over R ∈ SO(3). The translation direction is then recovered as the eigenvector associated with the minimal eigenvalue. A smooth approximation to the smallest eigenvalue via the log-sum-exp function is introduced, and iterative robust weights are employed. The implementation relies on automatic differentiation. Experiments on real data confirm the high reliability of the estimates.

This paper demonstrates the use of the API of the Kompas-3D CAD system to access the capabilities of its geometric kernel, which enable ray tracing through surfaces and components of complex shapes. To demonstrate the application potential of the developed algorithm, a simulation of a Newtonian mirror system was performed. To validate the accuracy of the simulation, an experimental setup was assembled. The results of both the computational analysis and the experiment are presented. For the purpose of simplifying the modeling, it was assumed that the patterns observed through the mirror system were self-luminous sources. The capability of the assembled mirror configuration to operate in conjunction with a thermal imager was investigated. Thus, the assembled mirror system demonstrated linear magnification of the radiating light source’s image without a significant loss of contrast.