Optical Field Research Articles

Investigation of borate glasses reinforced with iron (III) oxide [Fe2O3]: Preparation, physical, UV–Vis properties and γ-ray attenuation efficacy

Five samples of borate glasses reinforced with various ratios of Fe3+ ions with chemical formula (60-X)B2O3–10ZnO–10CdO–5Li2O–15Na2O-XFe2O3: (0.0 (Fe-0.0) ≤ X ≤ 1 (Fe-1.0) mol%) were prepared using the melt-quenching technique. The structure, physical, optical characteristics, and γ-ray attenuation properties of the prepared Fe-X glasses have been investigated. The amorphous state of Fe-X glasses confirmed by XRD observations. Density (ρglass) of the Fe-X glasses increased from 3.21 g cm−3 to 3.91 g cm−3. Molar volume (Vm) gradually reduced from 18.87 cm3/mol to 15.35 cm3/mol with increasing Fe2O3 content in the glass network from 0.0 to 1.0 mol%. The color of Fe-X glasses changed from yellow to brown according to the absorption bands located at around 385–412 nm and 407–429 nm within the visible spectrum. The indirect optical band gap (Eg) decreased from 3.37 eV to 2.78 eV, while the linear refractive index (no) increased from 2.31 to 2.45. Mass- (MAC) and linear- (LAC) attenuation coefficients increased as Fe3+ ions increased in the glass network. The Fe-1.0 sample with highest Fe2O3 content possessed the lowest values of half-value layer (HVL) and mean free path (MFP) shielding parameters. Results revealed that the suggested glass compositions can be applied in optical and radiation protection fields.

Properties, Synthesis and Emerging Applications of Graphdiyne: A Journey Through Recent Advancements.

Graphdiyne (GDY) is a new variant of nano-carbon material with excellent chemical, physical and electronic properties. It has attracted wide attention from researchers and industrialists for its extensive role in the fields of optics, electronics, bio-medics and energy. The unique arrangement of sp-sp2 carbon atoms, linear acetylenic linkages, uniform pores and highly conjugated structure offer numerous potentials for further exploration of GDY materials. However, since the material is at its infancy, not much understanding is available regarding its properties, growth mechanism and future applications. Therefore, in this review, readers are guided through a brief discussion on GDY's properties, different synthesis procedures with a special focus on surface functionalization and a list of applications for GDY. The review also critically analyses the advantages and disadvantages of each synthesis route and emphasizes the future scope of the material.

Polarization-Dependent Fiber Metasurface with Beam Collimating and Deflecting

Metasurfaces can arbitrarily manipulate the amplitude, phase, and polarization of optical fields on subwavelength scales. Due to their arbitrary manipulation and compact size, the metasurface can be well integrated with optical fibers. Herein, we demonstrate a polarization-dependent metasurface using birefringent meta-atoms, which can independently control X- and Y-polarization incident light. Each meta-atom allows for the division of phase into 16 steps ranging from 0 to 2 for both X- and Y-polarization, resulting in 256 nanopillars selected from the meta-atom library to satisfy the required phase. With the different effective refractive indices of the cuboid meta-atoms along the X- and Y-axis, we can achieve collimation of the X-polarization emitted beam from an optical fiber while deflecting orthogonally polarized light. As a result, the proposed metasurface collimates an X-polarized beam with a beam radius of 20 um at = 1 mm and 43.9 um at = 2 mm. Additionally, the metasurface can effectively deflect the Y-polarized beam to 36.01°, consistent with the results of the theoretical computation. The proposed metasurface exhibits a deflection efficiency of 55.6% for Y-polarized beams with a relative polarization efficiency of 82.2%, while the efficiency for the X-polarization is 71.4%. Our work is considered a promising application for optical communication, sensing, and quantum measurement.

Construction of Polysiloxane Induced Multilevel Bowl-shaped Janus Particles for Fabrication of Photoluminescent, Enhanced, Heat-insulative Poly(styrene-co-butyl acrylate) Latex Coating

Silica-based nanoparticles (SNPs) are highly regarded as advantageous nanofillers for composite coating, owing to their high surface area, robust mechanical properties, chemical stability, and adaptability for surface modification. Recent studies have unveiled the potential photoluminescence of SNPs induced by intrinsic defect sites, eliminating the need for additional fluorescein molecules. However, the inadequate quantum yield and complex preparation processes for generating defect sites within SNPs have constrained their broader applications. Herein, we propose a facile method to prepare Janus silicon-based nanoparticles with a hierarchical bowl-shaped structure (JHSNPs) through the emulsification of methyltriethoxysilane hydrolysis and condensation products, coupled with the capillary force during nanoparticle formation. The distinctive structure enhances the formation of dioxasilyrane (=Si(O2)) and silylene (=Si:) defects, thereby exhibiting strong blue photoluminescence. The JHSNPs then serve as nanofillers for commonly used poly(styrene-co-butyl acrylate) (SA) waterborne coatings, significantly enhancing their mechanical properties, abrasion resistance, and UV radiation resistance compared to the original SA coatings. Moreover, with just a 1% addition of JHSNPs, the composite coating exhibits visible fluorescence intensity, conferring the self-detecting monitoring properties for external scratches. Due to the hierarchical air-entrapping void structure, JHSNPs composite coatings demonstrate excellent thermal isolation performance, with a 22% reduction in thermal conductivity. The design of JHSNPs opens new avenues to expand the versatility of silica-based nanoparticles in composite coatings, especially in the optical, safety, and energy-saving fields.

Free Electron-Plasmon Coupling Strength and Near-Field Retrieval through Electron Energy-Dependent Cathodoluminescence Spectroscopy.

Tightly confined optical near fields in plasmonic nanostructures play a pivotal role in important applications ranging from optical sensing to light harvesting. Energetic electrons are ideally suited to probing optical near fields by collecting the resulting cathodoluminescence (CL) light emission. Intriguingly, the CL intensity is determined by the near-field profile along the electron propagation direction, but the retrieval of such field from measurements has remained elusive. Furthermore, the conditions for optimum electron near-field coupling in plasmonic systems are critically dependent on such field and remain experimentally unexplored. In this work, we use electron energy-dependent CL spectroscopy to study the tightly confined dipolar mode in plasmonic gold nanoparticles. By systematically studying gold nanoparticles with diameters in the range of 20-100 nm and electron energies from 4 to 30 keV, we determine how the coupling between swift electrons and the optical near fields depends on the energy of the incoming electron. The strongest coupling is achieved when the electron speed equals the mode phase velocity, meeting the so-called phase-matching condition. In aloof experiments, the measured data are well reproduced by electromagnetic simulations, which explain that larger particles and faster electrons favor a stronger electron near-field coupling. For penetrating electron trajectories, scattering at the particle produces severe corrections of the trajectory that defy existing theories based on the assumption of nonrecoil condition. Therefore, we develop a first-order recoil correction model that allows us to account for inelastic electron scattering, rendering better agreement with measured data. Finally, we consider the albedo of the particles and find that, to approach unity coupling, a highly confined electric field and very slow electrons are needed, both representing experimental challenges. Our findings explain how to reach unity-order coupling between free electrons and confined excitations, helping us understand fundamental aspects of light-matter interaction at the nanoscale.

Optical vectorial-mode parity Hall effect: a case study with cylindrical vector beams

The vectorial optical field (VOF) assumes a pivotal role in light-matter interactions. Beyond its inherent polarization topology, the VOF also encompasses an intrinsic degree of freedom associated with parity (even or odd), corresponding to a pair of degenerate orthogonal modes. However, previous research has not delved into the simultaneous manipulation of both even and odd parities. In this study, we introduce and validate the previously unexplored parity Hall effect for vectorial modes using a metasurface design. Our focus lies on a cylindrical vector beam (CVB) as a representative case. Through the tailored metasurface, we effectively separate two degenerate CVBs with distinct parities in divergent directions, akin to the observed spin states split in the spin Hall effect. Additionally, we provide experimental evidence showcasing the capabilities of this effect in multi-order CVB demultiplexing and parity-demultiplexed CVB-encoded holography. This effect unveils promising opportunities for various applications, including optical communication and imaging.

Optical properties of Heliconical Cholesterics: effects of losses and photonic density of states

ABSTRACT The investigation of both linear and nonlinear optical properties of Heliconical Cholesteric has been triggered by the easy tuning of the Bragg resonance that can be achieved either by low-frequency electric field or by light waves. However, in previous studies two factors that can strongly affect the optical behaviour of these materials have not been considered. The first one is absorption originated by a complex dielectric permittivity at optical frequency, the second one are the modifications of the photonic density of states incurred by electrical or optical tuning of the Bragg resonance. In this paper we report an extended work of simulations addressing the mentioned issues following the same calculation method presented in previous published papers. We report first the results of the simulations performed on the optical properties of Heliconical Cholesterics showing the effects due to isotropic and anisotropic losses comparing them to what obtained in conventional cholesteric liquid crystals. Then we focus on the photonic density of states near the Bragg resonance and show that its modification when applying increasing static or optical field must be taken into account when considering laser action based on these materials since tuning may remarkably affect the lasing threshold.

Design of a high-resolution magneto-plasmonic biosensor for analyte detection

Abstract This paper introduces the design of a magneto-plasmonic refractometric sensor aimed at achieving high resolution. This sensor consists of arrays of gold nanowires and layers of SiO2 and Co6Ag94, where the analyte is placed on the gold nanowires. A p-polarized optical field with a wavelength of 631 nm is used to excite the structure, which is applied in the range of 1º to 45º. A magnetic field is applied to z-axis to create the magneto-optical effect. The reflected optical field of the samples is used to calculate the signal of the transverse magneto-optical Kerr effect (TMOKE), which shows significant changes in the refractive index of the samples and the direction of the magnetic field. The highest displacement is 4º. The highest value of the figure of merit (FoM) is 3611 RIU-1, and the maximum sensitivity is obtained as 71 º/RIU.

Canonical and Poynting currents in propagation and diffraction of structured light: tutorial

The local propagation and the energy flux in structured optical fields are often associated with the Poynting vector. However, the local phase gradient (i.e., local wavevector) in monochromatic fields in free space is described by another fundamental quantity: the canonical momentum density. Distributions of the Poynting and canonical momentum densities can differ significantly from each other in structured fields. We examine the role of these quantities in the propagation and diffraction of structured optical fields, exemplified by various circularly polarized vortex beams carrying orbital angular momentum. We describe the canonical and Poynting momentum distributions in such beams, experimentally measure the local transverse momentum density by a Shack-Hartmann wavefront sensor, and investigate fine features of the diffraction of various vortex beams on a knife-edge aperture. In all cases, the measured local momentum density and local beam evolution are consistent with the canonical momentum distribution rather than the Poynting vector. Furthermore, we introduce the local angular velocity in vortex beams and determine the universal integral π angle of azimuthal rotation in an arbitrary (yet circularly symmetric) propagating and diffracting vortex beam. Finally, we discuss the “supermomentum” and “backflow” effects; both of these phenomena are examples of superoscillations and are related to the properties of the canonical momentum. Our results reveal the profound role of the canonical momentum in the evolution of light and demonstrate the importance of distinguishing between it and the Poynting vector in structured light.

3DOF displacement sensor based on the self-imaging effect of optical micro-gratings

In recent years, there has been an increasing demand for a multiple degrees of freedom (DOF) measurement system with high performance and high integration. Here, we report a 3DOF displacement sensor based on the self-imaging effect of optical micro-gratings. The optical field distribution behind a micro-grating with a period of 3 µm is analyzed theoretically. The transmission properties of a double-grating structure are investigated in theory. In the experiment, 3DOF displacement measurement within a range of 1 mm is demonstrated. Using an interpolation circuit with a subdividing factor of 1000, displacement measurement with a theoretical resolution of 3 nm is realized. The experimental resolution is ∼8nm. An error within 2 µm is obtained experimentally within a range of 1 mm for 3DOF measurement. With a few optical components such as a beam splitter prism and beam expanders, the sensor shows potential in developing ultra-compact multi-DOF displacement measuring systems. Together with a nanometric resolution, the 3DOF displacement sensor has shown great potential in applications such as high-precision mechanical engineering and semiconductor processing.

Understanding Wireless ChannelsThrough NeRF2

Despite Maxwell's formulation of the electromagnetic wave laws over a century and a half ago, accurately modeling the transmission of RF signals within electrically complex environments continues to be a formidable challenge. This complexity arises from intricate interactions of RF signals with various obstacles, such as reflections and diffractions. Inspired by the effective utilization of neural networks in computer vision for representing optical fields, this paper introduces NeRF2, a novel neural radio-frequency radiance field. NeRF2 conceptualizes a continuous, volumetric scene function to interpret RF signal propagation. Uniquely, NeRF2, once trained with limited signal measurements, can predict the characteristics and reception of a signal at an arbitrary point, given the transmitter's location. Functioning as a physical-layer neural network, NeRF2 amalgamates learned statistical models with physical ray tracing to create synthetic datasets, tailored for the training needs of application-layer artificial neural networks (ANNs). This integration, termed "turbo-learning," combines authentic and synthetic datasets, significantly augmenting ANNs' training efficacy. Experimental results illustrate that turbo-learning can substantially improve performance, with an estimated 50% enhancement. The efficacy of NeRF2 is further underscored in its applications in indoor localization and 5G MIMO systems.

Optical and electrical properties and applications of two-dimensional carbon-based nanomaterials

As an emerging material, two-dimensional (2D) carbon-based nanomaterials have unique optical and electrical properties due to their unique atomic layer structure. On the one hand, due to their high transmittance, high carrier mobility, controllable Fermi level, and wide spectral light saturation absorption characteristics, they can be applied in new-generation solar cells, organic light-emitting diodes, touch screens, and fiber optic devices. On the other hand, due to their unique nanostructure, they have high specific surface area, low diffusion distance, high conductivity, and ion conductivity. They can serve as substrates and work together with other materials as electrode materials for future fuel cells and lithium-ion batteries and have significant advantages in fields such as sensors. This article mainly summarizes the impact of two-dimensional carbon-based nanomaterials represented by graphene, Mxene, and 2D covalent organic frameworks (COFs) on their optical and electrical properties, and summarizes the latest practical applications and research progress of these nanomaterials in the field of optics and electronics. In addition, a corresponding summary and outlook have been made on the problems that need to be solved in future applications of 2D carbon-based nanomaterials.

Controllable Fabrication of Highly Ordered Spherical Microcavity Arrays by Replica Molding of In Situ Self-Emulsified Droplets.

Ordered spherical hollow micro- and nanostructures hold great appeal in the fields of cell biology and optics. However, it is extremely challenging for standard lithography techniques to achieve spherical micro-/nanocavities. In this paper, we describe a simple, cost-effective, and scalable approach to fabricate highly ordered spherical microcavity arrays by replica molding of in situ self-emulsified droplets. The in situ self-emulsion involves a two-step process: discontinuous dewetting-induced liquid partition and interfacial tension-driven liquid spherical transformation. Subsequent replica molding of the droplets creates spherical microcavity arrays. The shapes and sizes of the microcavities can be easily modulated by varying the compositions of the droplet templates or utilizing an osmotically driven water permeation. To demonstrate the utility of this method, we employed it to create a spherical microwell array for the mass production of embryoid bodies with high viability and minimal loss. In addition, we also demonstrated the optical functions of the generated spherical microcavities by using them as microlenses. We believe that our proposed method will open exciting avenues in fields ranging from regenerative medicine and microchemistry to optical applications.

A Highly Optical Anisotropic Hybrid Perovskite for Efficient Manipulation of Light Polarization

AbstractOptical anisotropic (e.g., birefringent) crystals can manipulate the polarization of light and thus are widely applied in modern optical fields. Common birefringent crystals are almost exclusively limited to inorganic oxides with small birefringence. Here, a new 1D hybrid halide perovskite PZPbCl3 (PZ = phenazine) is reported, which consists of perfectly parallel Pb–Cl chains and PZ cations. Remarkably, polarized optical observations show that even a PZPbCl3 crystal with micrometer thickness can modulate the polarized light efficiently. Furthermore, PZPbCl3 exhibits exceptional birefringence up to 0.65@546 nm, which is significantly larger than that of commercial oxide crystals. According to first‐principles calculations and polarizability anisotropy analyses, it is found that this birefringence is mainly ascribed to the linear polymerization of π‐conjugated rings in PZ cations. Due to the rich physical properties and structural diversity of hybrid perovskites, it is believed that the introduction of excellent birefringence into the hybrid perovskites will bring unprecedented opportunities to the future explorations of polarization‐dependent functional materials.

Analyzing the time-fractional (3 + 1)-dimensional nonlinear Schrödinger equation: a new Kudryashov approach and optical solutions

The paper focuses on investigating the time-fractional (3 + 1)-dimensional cubic and quantic nonlinear Schrödinger equation. We adopt the novel Kudryashov method to generate a distinct class of optical solutions for the current conformable fractional derivative problem. Our method explores various solution forms, including dark, wave, mixed dark-bright, and singular solutions. The soliton solutions we construct are visually represented to illustrate the influence of the fractional order derivative. Further, we elucidate the influence of solution parameters on the wave envelope, providing clear interpretations through 2D graphics presentations. The results underscore the efficacy of our approach in discovering exact solutions for nonlinear partial differential equations, especially in cases where alternative methods prove ineffective. The significance of the present paper lies in its contribution to advancing the understanding of the behavior of optical solutions in nonlinear systems, providing valuable insights for both theoretical and practical applications. In the field of nonlinear optics, this equation can describe the propagation of optical pulses in nonlinear media. It helps in understanding the behavior of intense laser beams as they propagate through materials exhibiting nonlinear optical effects such as self-focusing, self-phase modulation, and optical solitons.

Effect of Ga doping on the structural, optical, and electrical properties of ZnO nanopowders elaborated by sol-gel method

Nanostructured ZnO has received a considerable amount of interest, owing to its unique physical and chemical characteristics, as well as its remarkable performance in the fields of electronics, optics, and photonics. This work aims to study the influence of Ga dopant on the structural, optical, and electrical properties of ZnO nanopowders. Undoped and Ga-doped ZnO (GZO) nanopowders were successfully synthesised with the soft chemical sol-gel method. The solution was prepared using zinc acetate dihydrate and gallium (III) nitrate hydrate as precursors. The ethylene glycol is used as solvent. The X-ray diffractometer, scanning electronic microscope (SEM), UV–Vis, FTIR, and four-point probe method are used to analyse the properties of the synthesised powders. XRD and FTIR measurements show the growth of pure and Ga-doped ZnO crystals, which have a hexagonal wurtzite structure, and the average crystallite size varies from 9.09 nm to 24.8 nm. The nanospherical morphology of the nanopowders synthesised can be seen in the SEM images. The UV–visible spectroscopy shows that the optical gap energy increases with Ga concentration, from 3.59 eV to 3.67 eV. The I-V electrical measurements indicate that the breakdown voltage and the non-linear coefficient increase with Ga doping. This study will open the way for the investigation of a relationship between the electrical and nanostructural features of ZnO-based varistors for future device applications.

Finite pulse-time effects in long-baseline quantum clock interferometry

Quantum-clock interferometry has been suggested as a quantum probe to test the universality of free fall and the universality of gravitational redshift. In typical experimental schemes, it seems advantageous to employ Doppler-free E1–M1 transitions which have so far been investigated in quantum gases at rest. Here, we consider the fully quantized atomic degrees of freedom and study the interplay of the quantum center-of-mass (COM)—that can become delocalized—together with the internal clock transitions. In particular, we derive a model for finite-time E1–M1 transitions with atomic intern–extern coupling and arbitrary position-dependent laser intensities. We further provide generalizations to the ideal expressions for perturbed recoilless clock pulses. Finally, we show, at the example of a Gaussian laser beam, that the proposed quantum-clock interferometers are stable against perturbations from varying optical fields for a sufficiently small quantum delocalization of the atomic COM.

A new version of trial equation method for a complex nonlinear system arising in optical fibers

In this study, the dissipation problem of nonlinear pulse in mono mode optical fibers which is governed by the Fokas system (FS) is considered. The solutions of this system have an important role in comprehending the different wave structures in physical settings. Therefore, a new version of the trial equation method (NVTEM) is employed to present the new exact wave solutions of the FS. The advantage of the NVTEM is to use different root possibilities of a polynomial which shape the solutions of the related model. Primarily this system is converted to a nonlinear ordinary differential equation (NODE) via the traveling wave transform to apply the proposed method. Various exact wave solutions to the FS are obtained such as rational function, exponential function, hyperbolic function, and Jacobi elliptic function solutions. Thus, we have revealed solutions featly which are unlike the wave solutions previously found by other analytical methods. The present results depict the formation and development of such waves and their interactions. The exhibition of the solutions is given by 3D plots together with the corresponding 2D plots. The outcomes have shown that the proposed technique is abundant in achieving different wave solutions of many nonlinear differential equations in the field of optics.

Rate of Initial Optic Nerve Head Capillary Density Loss and Risk of Visual Field Progression

Rapid initial optic nerve head capillary density loss may be used to assess the risk of glaucoma visual field progression. To investigate the association between the rate of initial optic nerve head capillary density loss from optical coherence tomography angiography (OCTA) and visual field progression. This was a retrospective study of a longitudinal cohort at a glaucoma referral center. A total of 167 eyes (96 with primary open-angle glaucoma and 71 with glaucoma suspect) of 109 patients were monitored for a mean (SD) of 5.7 (1.4) years from January 2015 to December 2022. Data analysis was undertaken in April 2023. The rates of initial capillary density and average retinal nerve fiber layer loss were calculated from the first 3 optic nerve head OCTA and OCT scans, respectively, during the initial follow-up (mean [SD], 2.0 [1.0] years). Based on the median rate, eyes were categorized into fast and slow progressor groups. The association between initial capillary density change or retinal nerve fiber layer thinning and visual field progression was evaluated using linear-mixed and time-varying Cox models. A total of 167 eyes of 109 patients (mean [SD] age, 69.0 [11.1] years; 56 [51.4%] female and 53 [48.6%] male) were assessed. Eighty-three eyes were slow OCTA progressors, while 84 eyes were fast with mean capillary density loss of -0.45% per year and -1.17% per year, respectively (mean difference, -0.72%/year; 95% CI,-0.84 to -0.60; P < .001). Similarly, 83 eyes were slow OCT progressors, while 84 eyes were fast with mean retinal nerve fiber layer thinning of -0.09 μm per year and -0.60 μm per year, respectively (mean difference, -0.51 μm/year; 95% CI,-0.59 to -0.43; P < .001). The fast OCTA and OCT progressors were associated with more rapid visual field loss (mean difference, -0.18 dB/year; 95% CI,-0.30 to -0.06; P = .004 and -0.17 dB/year; 95% CI,-0.29 to -0.06; P = .002, respectively). Fast OCTA progressing eyes were more likely to have visual field progression (hazard ratio, 1.96; 95% CI, 1.04-3.69; P = .04). Seventeen of 52 eyes (32.7%; 95% CI, 32.5-32.8) with fast OCTA and OCT progression developed subsequent visual field likely progression. Rapid initial optic nerve head capillary density loss from OCTA was associated with a faster rate of visual field progression and a doubling of the risk of developing event progression in this study. These findings may support clinical use of OCTA and OCT optic nerve head measurements for risk assessment of glaucoma progression.

Beam shaping in light-sheet microscopy: an experimental analysis

Abstract Thanks to its unique optical sectioning capability, light-sheet fluorescence microscopy has proven to be a powerful technique for volumetric imaging of entire model organisms with high spatial and temporal resolution. For light sheet generation with scanned laser beams, holographic beam shaping offers precise control over the optical fields exciting the fluorescence. Various illumination schemes have been proposed, aiming for best image quality with regard to axial resolution, optical sectioning, illumination homogeneity and photobleaching while at the same time retaining a large field of view. Here, we have engineered and characterized a variety of beams and analyzed their imaging performance by using phantom samples and zebrafish embryos. These data may assist researchers to select the light sheet best suited to the imaging application at hand.