To ensure a more reliable and extensive underwater optical wireless communication link, the proposed composite channel model offers reference data as a guide.

Coherent optical imaging utilizes speckle patterns to furnish important characteristic information about the scattering object. Speckle patterns are typically captured using Rayleigh statistical models, in conjunction with angularly resolved or oblique illumination geometries. A two-channel, polarization-sensitive, portable imaging device is employed to directly visualize terahertz speckle fields within a collocated telecentric backscattering configuration. Measurement of the THz light's polarization state, achieved via two orthogonal photoconductive antennas, allows the presentation of the THz beam's interaction with the sample using Stokes vectors. Regarding surface scattering from gold-coated sandpapers, the method's validation displays a strong dependence of the polarization state upon the surface roughness and the frequency of the broadband THz illumination. In addition, we exhibit non-Rayleigh first-order and second-order statistical parameters, like degree of polarization uniformity (DOPU) and phase difference, for the purpose of measuring polarization randomness. A fast method of broadband THz polarimetric measurement is offered by this technique for field applications, with potential for detecting light depolarization in diverse applications, such as biomedical imaging and non-destructive examination.

The essential foundation of numerous cryptographic operations hinges on randomness, primarily manifested through random numbers. Despite adversaries' complete comprehension of and command over the protocol and the randomness source, quantum randomness can still be procured. However, a hostile actor can additionally manipulate the random element by deploying tailored detector-blinding attacks, which are exploitations of protocols that place confidence in their detectors. This quantum random number generation protocol, recognizing non-click events as valid data, is designed to simultaneously address vulnerabilities in the source and the highly targeted obfuscation of detectors. High-dimensional random number generation can be enabled by this method. Fungal bioaerosols Our protocol's capacity to generate random numbers for two-dimensional measurements is empirically verified, achieving a generation speed of 0.1 bit per pulse.

Photonic computing has become a focus of increasing interest due to its potential to accelerate information processing in machine learning applications. The mode-competition characteristics of multi-mode semiconductor lasers can be strategically deployed to address the multi-armed bandit problem in reinforcement learning for computing tasks. Employing numerical methods, this study examines the chaotic mode competition dynamics of a multimode semiconductor laser, influenced by both optical feedback and injection. The chaotic competition between longitudinal modes is observed, and it is controlled by the application of an external optical signal to a chosen longitudinal mode. The mode of greatest intensity is designated the dominant mode; the proportion of the injected mode escalates with increasing optical injection power. The optical feedback phases' differences account for the disparities in dominant mode ratio characteristics in relation to optical injection strength across various modes. A proposed method controls the characteristics of the dominant mode ratio by precisely manipulating the initial optical frequency detuning between the injection signal's optical frequency and the injected mode. We further analyze how the area characterized by the largest dominant mode ratios correlates with the injection locking range. The region displaying the highest dominant mode ratios is distinct from the injection-locking range. The control technique of chaotic mode-competition dynamics in multimode lasers is a promising approach for photonic artificial intelligence, with applications to both reinforcement learning and reservoir computing.

Statistical structural information, averaged from surface samples, is frequently derived from surface-sensitive reflection geometry scattering techniques like grazing incident small angle X-ray scattering when studying nanostructures on substrates. If a highly coherent beam is utilized, grazing incidence geometry allows for the investigation of a sample's absolute three-dimensional structural morphology. Coherent surface scattering imaging (CSSI), although similar to coherent X-ray diffractive imaging (CDI), differentiates itself by its employment of a small angle configuration within a grazing-incidence reflection geometry, maintaining its non-invasive nature. One limitation of applying conventional CDI reconstruction techniques to CSSI is the inadequacy of Fourier-transform-based forward models. These models fail to capture the dynamic scattering characteristics near the critical angle of total external reflection in substrate-supported samples. This challenge has been overcome by developing a multi-slice forward model that accurately reproduces the dynamical or multi-beam scattering emanating from surface structures and the substrate. In CSSI geometry, the forward model effectively reconstructs an elongated 3D pattern from a single scattering image through fast CUDA-assisted PyTorch optimization with automatic differentiation.

An ultra-thin multimode fiber, a compact and advantageous choice for minimally invasive microscopy, offers a high density of modes and high spatial resolution. For effective use in practice, the probe must possess both length and flexibility, a trait that unfortunately diminishes the imaging potential of a multimode fiber. This paper details the proposal and experimental demonstration of sub-diffraction imaging, accomplished via a flexible probe composed of a unique multicore-multimode fiber. A Fermat's spiral-distributed arrangement of 120 single-mode cores constitutes a multicore component. NSC 167409 supplier The cores, each, deliver stable light to the multimode section, ensuring optimal structured illumination for sub-diffraction imaging. A demonstration of fast sub-diffraction fiber imaging, resistant to perturbations, is presented, utilizing computational compressive sensing.

A persistent need in advanced manufacturing has been the stable propagation of multi-filament arrays in clear bulk media, where the gap between each filament can be precisely controlled. The interaction of two bundles of non-collinearly propagating multiple filament arrays (AMF) is reported to lead to the formation of an ionization-induced volume plasma grating (VPG). The VPG orchestrates the spatial arrangement of pulses within regular plasma waveguides by reconstructing electrical fields; this is evaluated against the self-formation of multiple, randomly distributed filaments stemming from noise. Biomass allocation Control over the separation distances of filaments in VPG is readily achievable by simply changing the crossing angle of the excitation beams. Beyond conventional methods, a groundbreaking technique was demonstrated for the creation of multi-dimensional grating structures in transparent bulk materials, achieved through laser modification and VPG.

A tunable narrowband thermal metasurface design is presented, employing a hybrid resonance through the interaction of a tunable permittivity graphene ribbon with a silicon photonic crystal. A gated graphene ribbon array, positioned near a high-quality-factor silicon photonic crystal supporting a guided mode resonance, displays tunable narrowband absorbance lineshapes, exhibiting quality factors exceeding 10000. Varying gate voltage alters the Fermi level in graphene, inducing a switch between high and low absorptivity states, and subsequently producing absorbance on/off ratios exceeding 60. We leverage coupled-mode theory for computationally efficient metasurface design elements, achieving an order of magnitude speed advantage compared to traditional finite element methods.

Within this paper, the angular spectrum propagation method and numerical simulations of a single random phase encoding (SRPE) lensless imaging system were employed to quantify spatial resolution and assess its dependence on the system's physical parameters. A compact SRPE imaging system comprises a laser diode to illuminate the sample positioned on a microscope slide, a diffuser to manipulate the light field passing through the sample object, and an image sensor to detect the intensity of the modulated light. We have undertaken a detailed study of the optical field, propagated from two-point source apertures, as registered by the image sensor. A correlation analysis was performed on the acquired output intensity patterns for varying lateral separations between the input point sources, relating the output pattern from overlapping point sources to the output intensity from separated ones. The lateral resolution of the system was determined through the process of measuring the lateral separation of point sources whose correlation dropped below 35%, a threshold established to mirror the Abbe diffraction limit of a comparable lens-based optical setup. When evaluating the SRPE lensless imaging system against an equivalent lens-based imaging system with matching system parameters, one finds that the lensless SRPE system exhibits comparable lateral resolution performance to its lens-based counterpart. Furthermore, we probed how this resolution changes in response to modifications in the lensless imaging system's parameters. The robustness of the SRPE lensless imaging system to object-to-diffuser-to-sensor distances, image sensor pixel sizes, and image sensor pixel counts is evident in the obtained results. In our estimation, this research constitutes the first exploration of the lateral resolution of lensless imaging systems, its robustness against multiple system parameters, and its contrast with lens-based imaging systems.

In the realm of satellite ocean color remote sensing, the atmospheric correction process is paramount. Despite this, the vast majority of existing atmospheric correction algorithms do not incorporate the effects of terrestrial curvature.