Hasil untuk "Optics. Light"

H. Eichler, P. Günter, D. Pohl

K. Bliokh, A. Aiello

We consider reflection and transmission of polarized paraxial light beams at a plane dielectric interface. The field transformations taking into account a finite beam width are described based on the plane-wave representation and geometric rotations. Using geometrical-optics coordinate frames accompanying the beams, we construct an effective Jones matrix characterizing spatial-dispersion properties of the interface. This results in a unified self-consistent description of the Goos–Hänchen and Imbert–Fedorov shifts (the latter being also known as the spin Hall effect of light). Our description reveals the intimate relation of the transverse Imbert–Fedorov shift to the geometric phases between constituent waves in the beam spectrum and to the angular momentum conservation for the whole beam. Both spatial and angular shifts are considered as well as their analogues for higher-order vortex beams carrying intrinsic orbital angular momentum. We also give a brief overview of various extensions and generalizations of the basic beam-shift phenomena and related effects.

Nir Shitrit, Igor Yulevich, Elhanan Maguid et al.

X. Xiao, B. Javidi, M. Martínez-Corral et al.

T. Lister, P. Wright, P. Chappell

Liangui Deng, Juan Deng, Zhiqiang Guan et al.

Polarization optics plays a pivotal role in diffractive, refractive, and emerging flat optics, and has been widely employed in contemporary optical industries and daily life. Advanced polarization manipulation leads to robust control of the polarization direction of light. Nevertheless, polarization control has been studied largely independent of the phase or intensity of light. Here, we propose and experimentally validate a Malus-metasurface-assisted paradigm to enable simultaneous and independent control of the intensity and phase properties of light simply by polarization modulation. The orientation degeneracy of the classical Malus’s law implies a new degree of freedom and enables us to establish a one-to-many mapping strategy for designing anisotropic plasmonic nanostructures to engineer the Pancharatnam–Berry phase profile, while keeping the continuous intensity modulation unchanged. The proposed Malus metadevice can thus generate a near-field greyscale pattern, and project an independent far-field holographic image using an ultrathin and single-sized metasurface. This concept opens up distinct dimensions for conventional polarization optics, which allows one to merge the functionality of phase manipulation into an amplitude-manipulation-assisted optical component to form a multifunctional nano-optical device without increasing the complexity of the nanostructures. It can empower advanced applications in information multiplexing and encryption, anti-counterfeiting, dual-channel display for virtual/augmented reality, and many other related fields. Metasurfaces made from an array of carefully orientated silver nano-brick polarizers on a silica glass substrate can manipulate the phase and amplitude of light. Fabricated and characterized by a team of researchers in China, Singapore and the UK, the so-called Malus metasurfaces are optimally designed to operate with red light and generate near-field greyscale patterns and far-field holographic images. Potential uses include image multiplexing and encryption, augmented-reality displays and other applications. The metasurfaces consist of nanoscale (160 nm long, 80 nm wide and 70 nm high) cuboids of silver which have a long axis and short axis. Simulations indicate that the nanobricks reflect 92.6% of incident 633 nm-light when its polarization is aligned along the long axis and transmit 95.3% when aligned to its short axis, thus acting as a nanoscale polarizer.

Rui Zhang, Fan Yang, Chenyang Zhao et al.

Conventional ultrasound (US) evaluation of enthesitis in psoriatic arthritis (PsA) is limited by its inability to quantify metabolic alterations such as hypoxia, a key driver of disease activity. We introduce an oxygenation-integrated multimodal photoacoustic/ultrasound (PA/US) imaging framework designed to quantify entheseal oxygen saturation (SO2) for assessing entheseal disease activity in PsA. In this cross-sectional study, 25 PsA patients underwent bilateral PA/US imaging of 12 entheses, where ultrasound lesions were scored using the Outcome Measures in Rheumatology scoring system, and PA-derived SO2 levels, quantified via dual-wavelength PA imaging, were classified into hyperoxia or hypoxia groups using k-means clustering. This approach provides metabolic insights complementary to conventional ultrasonic assessment. A composite score integrating hypoxia with US parameters was validated against clinical disease activity indices (Disease Activity Score 28-C-reactive protein, DAS28-CRP; Disease Activity Index for Psoriatic Arthritis, DAPSA). Among 300 entheses, 103 (34.3%) exhibited PA positivity, with 40 (38.8%) classified as hypoxia. Hypoxia scores independently predicted DAS28-CRP ([Formula: see text] = 0.618, p = 0.001) and DAPSA ([Formula: see text] = 0.612, [Formula: see text]). The hypoxia-optimized PAUS score demonstrated superior correlation with disease activity indices compared to conventional US (DAS28-CRP: r = 0.615, p = 0.001 versus r = 0.474, p = 0.017; DAPSA: r = 0.743, [Formula: see text] versus r = 0.567, p = 0.003), alongside superior diagnostic accuracy for minimal disease activity (area under the curve, AUC 0.776 versus 0.614, p = 0.008) and low disease activity (AUC 0.853 versus 0.772, p = 0.009). This multimodal scoring system enhances the stratification of PsA disease activity by providing unique metabolic insights, offering a potential tool for therapeutic monitoring and guiding treat-to-target strategies.

Tomás Santiago-Cruz, A. Fedotova, V. Sultanov et al.

All-dielectric optical metasurfaces are a workhorse in nano-optics, because of both their ability to manipulate light in different degrees of freedom and their excellent performance at light frequency conversion. Here, we demonstrate first-time generation of photon pairs via spontaneous parametric-down conversion in lithium niobate quantum optical metasurfaces with electric and magnetic Mie-like resonances at various wavelengths. By engineering the quantum optical metasurface, we tailor the photon-pair spectrum in a controlled way. Within a narrow bandwidth around the resonance, the rate of pair production is enhanced up to 2 orders of magnitude, compared to an unpatterned film of the same thickness and material. These results enable flat-optics sources of entangled photons—a new promising platform for quantum optics experiments.

Yang Chen, W. Du, Qing Zhang et al.

M. Piccardo, Michael de Oliveira, Andrea Toma et al.

Geometric arrays of vortices found in various systems owe their regular structure to mutual interactions within a confined system. In optics, such vortex crystals may form spontaneously within a resonator. Their crystallization is relevant in many areas of physics, although their usefulness is limited by the lack of control over their topology. On the other hand, programmable devices like spatial light modulators allow the design of nearly arbitrary vortex distributions but without any intrinsic evolution. By combining non-Hermitian optics with on-demand topological transformations enabled by metasurfaces, we report a solid-state laser that generates 10 × 10 vortex laser arrays with actively tunable topologies and non-local coupling dictated by the array’s topology. The vortex arrays exhibit sharp Bragg diffraction peaks, witnessing their coherence and topological charge purity, which we spatially resolve over the whole lattice by introducing a parallelized analysis technique. By structuring light at the source, we enable complex transformations that allow to arbitrarily partition orbital angular momentum within the cavity and to heal topological charge defects, thus realizing robust and versatile resonators for applications in topological optics. A solid-state laser that generates 10 × 10 vortex laser arrays is demonstrated. The topologies are actively tunable.

Bo Gao, Jia-Ning Guo, Jian Zhang et al.

Visible light communication (VLC) integrates illumination and communication, offering significant potential for 6G mobile communications. In 6G communications, reliability and low latency are critical. To meet these demands, finite blocklength codewords are employed for data transmission. For indoor VLC scenarios, multiple light-emitting diodes (LEDs) serve as transmitters, with each transmitter operating under distinct optical power constraints tailored to user requirements. In this paper, a multidimensional constellation design based on geometric shaping is proposed for multi-input single-output (MISO) VLC with per-LED optical power constraints. This design employs truncated cubic shaping to design the equivalent transmitted signal and decomposes it into transmitted signals using a partition-based greedy decomposition. The proposed scheme designs signals in the finite blocklength regime while adhering to per-LED optical power constraints. Simulation results for indoor MISO VLC systems demonstrate the advantages of the proposed scheme over benchmark schemes and quantify the performance gains as well as the gap to the Shannon limit.

Ye Zhang, Meiyun Xia, Wei Song et al.

In recent years, depression has emerged as a significant global health concern, prompting many individuals to seek pharmacological interventions. The identification of inflammatory changes in the hippocampus of depressed patients has highlighted a potential therapeutic target. Nevertheless, the effectiveness of medications targeting these specific alterations has yet to be fully substantiated. Preliminary research has suggested the potential benefits of photobiomodulation (PBM) as a treatment for depression, with no significant adverse effects reported. This study utilized near-infrared light at intensities of 50[Formula: see text]mW/cm2 and 300[Formula: see text]mW/cm2 to illuminate mice with chronic mild stress (CMS)-induced depression model, aiming to explore the therapeutic effects of PBM on depression. The findings revealed that when exposed to a power density of 300[Formula: see text]mW/cm2, the mice exhibited enhanced behavioral outcomes, accompanied by decreased levels of inflammatory cytokines such as IL-1[Formula: see text], IL-1[Formula: see text], IL-5, and IL-6 in the hippocampus. A noteworthy association was observed between behavioral manifestations and inflammatory cytokine levels. This study posits that PBM at an intensity of 300[Formula: see text]mW/cm2 is a viable nonpharmacological intervention for depression, as it demonstrates a notable enhancement in depressive symptoms and the regulation of inflammatory mediators within the hippocampal region of the brain. However, this study is constrained by the particular PBM parameters employed; therefore, additional research is necessary to investigate a broader spectrum of doses and treatment durations in order to enhance the therapeutic application and deepen the understanding of the underlying mechanisms.

Marta Gladysiewicz

The mid infrared (mid-IR) spectral range holds significant importance in laser technology because of its unique characteristics and broad range of potential applications, including gas sensing. This paper discusses the possibility of constructing structures for mid-IR lasers operating on the InSb substrate based on interband transitions. The study demonstrates the potential of bismuth-related quantum wells (QWs) and alloyed semiconductor materials for long-wavelength (LWIR) laser applications, providing insight into their electronic properties and potential for device optimization. Gain spectra were calculated for different scenarios, revealing the dominance of TE or TM modes depending on the material composition and carrier concentration. The gain spectrum widens with increasing QW width, and its intensity decreases with the growth of As. The material system under consideration is well suited for the (6&#x2013;8, <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m) wavelength range and can be considered a promising candidate for LWIR devices.

E. Ivchenko

Lei Wang, Xiaoxian Liu, Guoguang Lu et al.

Herein, A new differential magnetic-field probe with parasitic elements is presented. The proposed probe has two pairs of shorted differential loops as parasitic elements, which could enhance the detection sensitivity owing to the increased detection area. The proposed probe comprises a U-shaped loop with two outputs as the driven element, two pairs of shorted differential loops as parasitic elements, a pair of shorted via, a pair of connected via, and many shielded vias. First, the usual single-loop probe is theoretically studied. Second, a pair of shorted loops is inserted into the differential single-loop probe as a parasitic element to receive more magnetic flux. Third, another pair of shorted loops is etched into the probe to further improve the detection sensitivity. The corresponding simulation results are presented to prove the effectiveness of the design. Finally, the proposed probe with parasitic elements is designed, printed, and evaluated. Measurement results reveal that the designed probe has high detection sensitivity.

Giles Blaney, Angelo Sassaroli, Sergio Fantini

This compendium review focuses on the spatial distribution of sensitivity to localized absorption changes in optically diffuse media, particularly for measurements relevant to near-infrared spectroscopy. The three temporal domains, continuous wave, frequency domain, and time domain, each obtain different optical data types whose changes may be related to effective homogeneous changes in the absorption coefficient. Sensitivity is the relationship between a localized perturbation and the recovered effective homogeneous absorption change. Therefore, spatial sensitivity maps representing the perturbation location can be generated for the numerous optical data types in the three temporal domains. The review first presents a history of the past 30 years of work investigating this sensitivity in optically diffuse media. These works are experimental and theoretical, presenting one-, two-, and three-dimensional sensitivity maps for different Near-Infrared Spectroscopy methods, domains, and data types. Following this history, we present a compendium of sensitivity maps organized by temporal domain and then data type. This compendium provides a valuable tool to compare the spatial sensitivity of various measurement methods and parameters in one document. Methods for one to generate these maps are provided in Appendix A, including the code. This historical review and comprehensive sensitivity map compendium provides a single source researchers may use to visualize, investigate, compare, and generate sensitivity to localized absorption change maps.

Jiale Wang, Biao Ding, Qingfeng Wu et al.

To investigate the laser-based displays that can offer the light source with a high level of photobiological safety and are suitable for users of different ages, this research optimizes the light source of the three-primary laser-based displays from its peak wavelength and the fractions of radiant flux. The non-linear program based on genetic algorithm is used to set the color gamut coverage over 90&#x0025; and the correlated color temperature at 6500K. Find suitable peak wavelength and fractions of radiant flux with the premise of less than the blue light hazard (BLH) caused by the D65 light source to the 1 year, and select the result with the maximum circadian action factor (CAF) as the optimization for each age. Meanwhile, this research explores the effect that a change in the peak wavelength and fractions of radiant flux near the optimal results on CAF and BLH in different age groups. It provides reference for the design of health consideration laser displays for different age users in the daily working environment.

Bowen Liu, Jialuo Cheng, Maoxiong Zhao et al.

Abstract Metalens, characterized by their unique functions and distinctive physical properties, have gained significant attention for their potential applications. To further optimize the performance of metalens, it is necessary to characterize the phase modulation of the metalens. In this study, we present a multi-distance phase retrieval system based on optical field scanning and discuss its convergence and robustness. Our findings indicate that the system is capable of retrieving the phase distribution of the metalens as long as the measurement noise is low and the total length of the scanned light field is sufficiently long. This system enables the analysis of focal length and aberration by utilizing the computed phase distribution. We extend our investigation to measure the phase distribution of the metalens operating in the near-infrared (NIR) spectrum and identify the impact of defects in the sample on the phase. Additionally, we conduct a comparative analysis of the phase distribution of the metalens in air and ethanol and observe the variations in the phase modulation of the metalens in different working mediums. Our system provides a straightforward method for the phase characterization of metalens, aiding in optimizing the metalens design and functionality.

Zeng Wang, Guangxi Hu, Haimei Luo et al.

A hybrid plasmonic waveguide Bragg grating (HPWBG) consisting of a polyvinyl alcohol (PVA) microfiber coupled with metal strips oriented at right angles is reported for simultaneous measurement of humidity and temperature. Due to the convenient adherence of PVA microfiber to metal gratings and its easy connectivity to silica fiber tapers, the hybrid plasmonic waveguide sensor exhibits high flexibility. Numerical calculation reveals that TM polarization shows more prominent Bragg reflection owing to hybrid plasmonic modes exciting. Two hybrid plasmonic TM modes, namely the fundamental mode and the high-order mode, are excited, resulting in two separate reflection peaks. As the two reflection peaks exhibit different behaviors in response to changes in humidity and temperature, simultaneous measurement of humidity and temperature can be realized through a sensitivity coefficient matrix. The experimental results show that the humidity sensitivity reaches &#x2212;1.98 nm&#x002F;&#x0025;RH in the range of 30&#x0025;&#x2013;90&#x0025;RH and the temperature sensitivity is &#x2212;0.64 nm&#x002F;&#x00B0;C within a temperature range of 20&#x2013;90 &#x00B0;C for a PVA microfiber diameter of 1.57 &#x03BC;m. The excellent sensing performance, compactness, and flexibility of the hybrid plasmonic waveguide make it an encouraging choice for humidity and temperature sensing applications.

Denis N. Bulanov, Efim A. Khazanov, Andrey A. Shaykin et al.

A programming library was developed, based on Stratton-Chu diffraction integrals for calculating reflected optical fields. Dipole-type focusing schemes with tunable number of beams and mirror placements were studied, considering the influence of phase distortion and aberrations. The intensity above $3\times 10^{26}$ W/cm$^2$ was found theoretically attainable in a system of 12 beams of 50 PW each with about 90 % of that value realistically achievable.