Applied Physics B最新文献

A non-contact method for assessing the local geometrical thickness, porosity, and effective refractive index of synthetic opals using spectral optical coherence tomography is proposed. This approach was employed to investigate the diffusion of aqueous glycerol solutions with varying concentrations into the macropores of synthetic opals pre-filled with water. The kinetics of changes in the optical thickness and refractive index of synthetic opals during the optical clearing process were monitored. The obtained data were analyzed using the least-squares method, which enabled the determination of porosity 20–30%, refractive index 1.37–1.45, and geometrical thickness 0.94–1.17 mm of the synthetic opals. The results were validated by an alternative method of refractive index matching. It is demonstrated that the proposed approach can be applied to the analysis of local structural and optical parameters of porous materials, offering promising prospects for applications in materials science and bioengineering.

This research offers a thorough analysis of the non-classical features associated with cavity radiation produced by a combination of superposed non-degenerate three-level lasers and non-degenerate subharmonic light beams. The Q-functions of the individual light beams are utilized to derive the Q-function for the superposed cavity radiation. From this derived Q-function, we analyze the expectation values of operators. Using the relevant expectation values (correlations) of these operators, we calculate the quantum discord for the superposed cavity light beams being studied. The results indicate that quantum discord increases with the linear gain coefficient and atomic coherence, while it decreases with the parameter (gamma ) and population inversion, (xi ). Although the trends of forward and backward quantum discord are generally similar, it is distinctly observed that the forward quantum discord is consistently less than the backward quantum discord. The variation in quantum discord observed in the forward and reverse processes is primarily linked to the differences in the mean photon numbers of mode-a and mode-b within the non-degenerate three-level laser system. Additionally, a juxtaposition of quantum discord with entanglement, evaluated through the Logarithmic Negativity criterion, reveals that the quantum discord associated with the superposed cavity radiation remains above the Logarithmic Negativity level. Nonetheless, for certain values of (gamma ) exceeding 0.3, quantum discord may fall below the Logarithmic Negativity threshold. This observation underscores the notion that quantum discord is a significant aspect of entanglement. Through the application of quantum discord and the Logarithmic Negativity criterion, it is established that the superposed non-degenerate cavity radiation manifests quantum properties and entanglement.

Scalar vortex beams may be generated using multiple techniques. However, the generation of vector vortex beams from a single optical component has fewer options. A liquid crystal plate called a q-plate has a distribution of optical axis alignments that can vary radially and azimuthally. These plates provide a very robust and cost-effective method of generating vector-vortex and structured beams based on the Pancharatnam-Berry phase. Multi-plate gadgets can be generated from these plates to generate full-Poincaré beams, wavelength-tunable q-plates, and a wide range of structured light. The successful realization of such gadgets relies on the careful characterization of individual plates, which are characterized by their topological charge, offset angle, and retardance at the designed wavelength. In order to make complex multi-plate devices, a thorough mathematical modeling followed by multiple experimental measurements and simulations is essential. In the present work, a systematic and thorough protocol for such a characterization is provided with ample experimental and simulation results. The results presented here should be of value to experimentalists and device makers alike.

The incorporation of topology into physical dimensions of light introduces global and quantized characteristics that give rise to a new class of optical fields with enhanced robustness and functionality. Topological light fields are defined by nontrivial topological invariants, such as winding numbers, linking numbers, and skyrmion or Hopf indices, encoded in phase singularities, polarization textures, or spatiotemporal structures, providing a unifying framework for understanding and engineering complex optical structures. In this review, we present an overview of the fundamentals and applications of topological light fields in free space. We first classify topological light according to two-dimensional cross-profile topology, three-dimensional spatially-propagated topology, and spatiotemporal topology, and summarize the underlying physical principles, generation methods, and characterization techniques for representative structures, including optical vortices, vector beams, skyrmions, optical knots, Möbius strips, Hopfions, and spatiotemporal optical vortices. We then survey recent advances in applications enabled by topological light fields, covering high-capacity and robust optical communications, topological quantum entanglement, optical storage, precision optical metrology, and multidimensional optical trapping. Finally, we discuss key challenges and emerging opportunities in this rapidly evolving field. This review aims to provide a detailed roadmap for both fundamental research and technological development in free-space topological photonics.

We examine the reduction of silver nanoparticle (AgNP) size under an external magnetic field within a classical nucleation theory framework combined with a sphere-packing description of atomic assembly. The model incorporates magnetic free-energy contributions arising from the coupling between the applied field and the magnetic susceptibility of the nucleating material, yielding a closed-form relation between nanoparticle radius and field strength. Our approach reproduces the experimentally observed decrease in the most-probable particle radius from approximately (170text { nm}) at (mathcal {B}=49.27text { mT}) when the magnetic field is oriented parallel to the stirring plane, and to (155text { nm}) at (mathcal {B}=180.78text { mT}) in the perpendicular configuration. Across the investigated field range, the theoretical predictions remain consistent with experimental measurements obtained under continuous mechanical stirring, supporting the interpretation that the observed size reduction originates from a magnetic-field-induced modification of the nucleation free-energy landscape. Within the limits of classical capillarity and spherical demagnetization, the results provide a physically transparent and computationally efficient framework for understanding magnetic-field-controlled nanoparticle size selection.

Nonreciprocal photonic spin Hall effect manifests it as the different spin dependent reflected/transmitted transverse splittings of linearly polarized incident waves at two opposite wave propagation directions. However, its realization remains obscure. Here, we report the discovery of the prominent nonreciprocal photonic spin Hall effect in a bulk Dirac semimetal based on quasiperiodic Tribonacci photonic crystal, which is evidenced by the significantly large reflected spin shift along one propagation direction but the trivial spin shift along the opposite propagation direction due to its asymmetrical geometrical structure and electromagnetic field distribution. In addition, the Fermi energy of the bulk Dirac semimetal can be continuously modified by the external stimulus, which enables the effective control of the nonreciprocal photonic spin Hall effect in the Dirac semimetal based Tribonacci photonic crystal. Our results open up the alternative platform to generate the controllably nonreciprocal photonic spin Hall effect in the quasiperiodic systems via the combination of the bulk Dirac semimetals and Tribonacci photonic crystal.

Spatio-spectral measurement of ultrashort-pulse beam is very important for the performance optimization of laser facilities. A reference-free, spectrally resolved measurement method based on ptychography with an advanced iterative algorithm for high-precision synthesis of full-spectrum data is proposed. We designed an integrated measurement device with robust implementation and high reliability. The device was successfully applied in a target chamber of a terawatt-class ultrashort-pulse laser facility. The spatio-spectral complex amplitude of a complicated pulsed laser was accurately reconstructed with high spatial resolution of 11 μm and some wavelength-dependent spatial phase characteristics in the laser pulse were identified. This method offers a promising approach for advanced beam characterization of high-power femtosecond laser system.

This work investigates the viscoelastic properties and folding dynamics of red blood cells (RBCs) at the single-cell level, using optical tweezers. Cell elasticity and membrane viscosity are measured by dragging optically trapped RBCs against the surrounding plasma environment. A custom-developed image processing algorithm is employed for high-throughput processing of single-cell trapping data. The effect of refrigerated plasma storage on the mechanical properties of the cells is investigated by measuring their folding dynamics after one day and seven days of storage for several trapping laser powers and the findings indicate that mechanical stiffening of the cells takes place while they are stored. A novel correlation between RBC area and folding time is established. These results provide new insights into the mechanical behavior of RBCs, which are related to several blood disorders.

We show that, in a vast class of multiple-pulse laser–matter interaction settings, the S-pulse laser damage probability and the expected number of pulses before the damage can be expressed in the S >  > 1 limit as closed-form functions of the laser fluence and the variation coefficient of laser-driver statistics. The statistics of such rare laser-damage events is found in the class of generalized extreme-event distributions, allowing multiple-pulse laser damage to be understood in terms of universal properties of extreme-event statistics. As a demonstration of its descriptive power, this approach is shown to provide an accurate, physically insightful fit for the reference experimental data for multipulse laser damage in optical-grade glasses and nonlinear crystals.

Impurity elements such as lanthanum (La) and neodymium (Nd) in nuclear fuel can adversely impact its efficiency and operational lifespan, making their accurate quantification essential. This study employed laser-induced breakdown spectroscopy (LIBS) to analyze La and Nd in unknown thorium (Th) uranium (U) mixed oxide (Th-U MOX) fuel materials. A novel difference method (DM) was integrated with the standard addition method (SAM) and compared with the conventional extrapolation method (EM). Following a rigorous comparison, three analytical lines for each element were selected: 442.99 nm, 465.55 nm and 545.51 nm for La, and 430.35 nm, 445.15 nm and 529.31 nm for Nd. At 465.55 nm, the SAM-DM approach predicted a La concentration of 530 ppm with a relative error of the mean (REM) of 5.2%, markedly lower than the EM result of 600 ppm (REM = 24.9%). For Nd at 529.31 nm, SAM-DM yielded 475 ppm with 4.5% REM, compared to 550 ppm and 10.6% REM by EM. These results confirm the superior accuracy of SAM-DM over EM, particularly at the selected analytical lines. The two lines were subsequently used to construct optimized calibration curves, yielding limits of detection (LODs) of 155.22 ppm for La and 355.97 ppm for Nd. Furthermore, leave-one-out cross-validation (LOO-CV) confirmed the robustness of the proposed strategy, with prediction errors generally below 9% except in low concentration cases. Overall, this work establishes a reliable analytical framework for nuclear fuel impurity quantification by pioneering the combination of SAM-DM with LIBS for Th-U MOX analysis, demonstrating strong potential for quality control and safeguards applications.