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The field of geometrical optics features a broad knowledge base concerning conceptual learning difficulties and student conceptions. However, in contrast to other areas of physics, no widely used standard test instrument exists to assess middle school students' conceptual knowledge of geometrical optics. This is even more true for other areas of the electromagnetic spectrum. For this reason, a concept test was developed for an intervention study to collect preconceptions about visible light as well as preconceptions about infrared radiation in the subject area of reflection and transmission. A pilot study with 108 middle school students preceded final revisions and implementation in the main study of 820 learners aged 12-16. The measurement model is presented for the developed concept test with the subscales 'preconceptions and knowledge about reflection and transmission in visible optics', 'preconceptions and knowledge about reflection and transmission in infrared optics' and 'applied knowledge on reflection and transmission in visible and infrared optics'. The results show that the concept test validly captures the development of preconceptions and knowledge regarding specific aspects of reflection and transmission of the part of the electromagnetic spectrum from 3 µm to 380 nm.

The limitation of conventional visual acuity assessment, which primarily focuses on individual eye performance (monocular visual acuity tests). This study addresses this limitation by emphasizing the importance of binocular vision, where both eyes work together. Binocular vision provides numerous advantages, such as improved depth perception, a wider field of view, reduced visual fatigue, and binocular summation. The article introduces a new mathematical model based on the physics of constructive interference in light waves and the anatomy of visual nerves. This model yields an equation that quantifies how weakness in one eye affects the visual acuity of the other. By analyzing the correlation between the rates of visual weakness in each eye and the corresponding distances, utilizing the Snellen 6-meter test, valuable insights are gained into the complex interplay between eye deficiencies and their collective impact on overall visual acuity. The equations derived from this study can have significant implications for eye care professionals, clinicians, and patients, contributing to a more comprehensive understanding of visual impairments and enriching the field of optics and vision science.

HOBIT, which stands for "Hybrid Optical Bench for Innovative Teaching and learning" is an educational platform that leverages the combination of numerical simulation and physical manipulation to facilitate learning of complex phenomena and motivate users about wave optics in practical work. HOBIT operates in real time and is self-adaptive, providing realistic displays of optical phenomena with virtual augmentations designed to facilitate their understanding. HOBIT makes it quick and easy to build any reconfigurable optical experiment. Students can manipulate optical components and observe the changes induced on detectors and displays. We detail the technology, the simulation model and the initial teaching aids. Current and future enhancements should meet the needs of students at different levels, from high school to higher education degrees.

Clear and rigorous quantum reasoning is needed to explain quantum physical phenomena. As pillars of true quantum physical explanations, we suggest specific quantum reasoning derived from quantum physical key ideas. An experiment is suggested to support such a quantum reasoning, in which a quantized radiation field interacts with an optical beam splitter, leading to experimental results conflicting with classical physical predictions. The results, however, can be explained consistently with a quantum reasoning based on the key ideas of probability, superposition, and interference (PSI). In this quantum optical key experiment the optical beam splitter prepares a superposition of single photon states and a Michelson interferometer is used to detect the superposition via controlled propagation phases. Although different single photon experimental setups (aimed at helping students to gain access to foundational issues in quantum physics) have been discussed in the past, the wave-particle dualism bound to classical physics maintains its predominance as an explanation pattern for the interpretation of these experiments. The study presented here investigates the effect of the quantum optical key experiment on the ability of students to use quantum reasoning based on the key ideas of PSI to overcome the naive wave-particle dualism. The current state of relevant studies that test student access to quantum physics can roughly be divided into two distinct areas: one tests how mathematical abilities help them to understand quantum physics and one tests how nonmathematical representations of a set of specific quantum theoretical traits ("Wesenszüge") lead to a deeper understanding of quantum physics. There is a lack of questionnaires that focus on the idea of developing quantum reasoning based on superposition, probability, and interference of quantum states combined with a real experiment using true quantum light. In the first part of the article, we describe the physical modeling and present the development of the questionnaire. The set of items has been constructed from newly developed items and combined with well-tested ones. The validation of the set addresses qualitative and quantitative methods. In the second part, we give a pre- and poststudy examination of the impact of the quantum optical key experiment on students' quantum reasoning. A significant increase in the number of students using quantum arguments is based on PSI reasoning for the explanation of an interference, such as the behavior of single photon states. Though the increase is significant, we found only minor changes in a particular issue to the students' reasoning when approaching quantum physics as illustrated by a sample of answers given in the second part of the article. The concept of quantum states and the principle of superposition still appear particularly difficult.

[This paper is part of the Focused Collection on Instructional labs: Improving traditions and new directions.] This manuscript presents a case study of an introductory physics student who, during the remote learning conditions imposed during the COVID-19 pandemic, found inspiration within a new, open-inquiry, project-based, laboratory curriculum designed at Portland State University. The phenomenon investigated by the study subject was intriguing to both the student and the lab instructors for its unfamiliar and instructive optical effect: a ring-shaped pattern or halo created by a laser diffusely reflected in a shallow body of water. Drawing on classwork and interview responses, this study shows that the subject achieved many expected curriculum outcomes, particularly with respect to experimental design and data analysis tasks, indicating that the course's open-inquiry structure can be effective while offering students a free choice of what to investigate in a laboratory class. Additionally, the case study shows that the halo phenomenon is pedagogically rich as it combines refraction, diffuse reflection, and total internal reflection in a nontrivial way, thereby answering calls by physics education researchers for more complex, realistic examples in geometric optics instruction. Finally, this case also highlights challenges students may experience interpreting diffuse reflection and determining the position of optical features beyond image formation, not commonly a focus of introductory physics courses, textbooks, and education research.

Wave optics is a mandatory part of Croatian secondary school physics curriculum for students in the final year of secondary school (age 18-19). Many physics education research studies have shown that it is a difficult physics topic for both university and secondary school students. An inquiry-based teaching sequence on wave optics, designed for eight 45-min teaching periods, was developed by the authors. The sequence included four investigative students' experiments on the topics of interference, diffraction, and polarization of light, as well as several teacher demonstrations. The experimental group included six classes of students from six different Croatian urban secondary schools, who underwent the teaching intervention with the new inquiry-based sequence on wave optics, whereas the control group consisted of six classes from the same schools, taught in a predominantly lecturing way. Both groups were post-tested with the same instrument, the Conceptual Survey on Wave Optics (CSWO), to evaluate the research hypothesis that the new sequence might improve students' conceptual understanding better than the traditional teaching. The results of the experimental and control groups were analyzed and compared using the Rasch analysis. The results show that the experimental group outperformed the control group in four out of five conceptual areas probed by the CSWO, suggesting that the new inquiry-based teaching sequence may contribute to stronger development of secondary school students' conceptual understanding of wave optics, especially concerning typical wave optics patterns, reasoning from experiments, and explaining basic wave optics phenomena. A questionnaire on attitudes toward the teaching intervention was administered to students and it was found that students generally liked the inquiry-based teaching intervention and expressed positive attitudes to interactive, experimental, and collaborative aspects of physics teaching. The results are very promising, but their generalization may be limited by the selection of the students, as well as by the short duration of the teaching intervention and the relatively small breadth of the covered topics.

Previous work has demonstrated similarities and differences between aerial and terrestrial image viewing. Aerial scene categorization, a pivotal visual processing task for gathering geoinformation, heavily depends on rotation-invariant information. Aerial image-centered research has revealed effects of low-level features on performance of various aerial image interpretation tasks. However, there are fewer studies of viewing behavior for aerial scene categorization and of higher-level factors that might influence that categorization. In this paper, experienced subjects' eye movements were recorded while they were asked to categorize aerial scenes. A typical viewing center bias was observed. Eye movement patterns varied among categories. We explored the relationship of nine image statistics to observers' eye movements. Results showed that if the images were less homogeneous, and/or if they contained fewer or no salient diagnostic objects, viewing behavior became more exploratory. Higher- and object-level image statistics were predictive at both the image and scene category levels. Scanpaths were generally organized and small differences in scanpath randomness could be roughly captured by critical object saliency. Participants tended to fixate on critical objects. Image statistics included in this study showed rotational invariance. The results supported our hypothesis that the availability of diagnostic objects strongly influences eye movements in this task. In addition, this study provides supporting evidence for Loschky et al.'s (Journal of Vision, 15(6), 11, 2015) speculation that aerial scenes are categorized on the basis of image parts and individual objects. The findings were discussed in relation to theories of scene perception and their implications for automation development.

In this paper, an exact analytical solution is presented for achieving coherent population transfer and creating arbitrary coherent superposition states in a five-state chainwise system by a train of coincident pulses. We show that the solution of a five-state chainwise system can be reduced to an equivalent three-state Λ-type one with the simplest resonant coupling under the assumption of adiabatic elimination together with a requirement of the relation among the four coincident pulses. In this method, the four coincident pulses at each step all have the same time dependence, but with specific magnitudes. The results show that, by using a train of appropriately coincident pulses, this technique not only enables complete population transfer, but also creates any desired coherent superposition between the initial and final states, while the population in all intermediate states is effectively suppressed. Furthermore, this technique can also exhibit a one-way population transfer behavior. The results are of potential interest in applications where high-fidelity multi-state quantum control is essential, e.g., quantum information, atom optics, formation of ultracold molecules, cavity QED, nuclear coherent population transfer, and light transfer in waveguide arrays. [ABSTRACT FROM AUTHOR]

This article explores the shift in chemical physics research towards studying single molecules and nanoparticles instead of bulk samples. Advancements in experimental techniques, such as single-molecule absorption and fluorescence spectroscopy, have made this shift possible. The article discusses various observations made through single-molecule spectroscopy, as well as theoretical considerations and applications in biology, materials science, and nanophotonics. It provides a summary of studies conducted using single-molecule spectroscopy in different disciplinary categories, demonstrating its interdisciplinary nature. The article concludes by discussing the challenges and future directions in the field, including integrating particle tracking with time-dependent spectroscopy and actively manipulating nanoscale objects. [Extracted from the article]

The effects of optical feedback on a terahertz (THz) quantum-cascade metasurface vertical-external-cavity surface-emitting laser (QC-VECSEL) are investigated via self-mixing. A single-mode 2.80 THz QC-VECSEL operating in continuous-wave is subjected to various optical feedback conditions (i.e., feedback strength, round-trip time, and angular misalignment) while variations in its terminal voltage associated with self-mixing are monitored. Due to its large radiating aperture and near-Gaussian beam shape, we find that the QC-VECSEL is strongly susceptible to optical feedback, which is robust against misalignment of external optics. This, in addition to the use of a high-reflectance flat output coupler, results in high feedback levels associated with multiple round-trips within the external cavity-a phenomenon not typically observed for ridge-waveguide QC-lasers. Thus, a new theoretical model is established to describe self-mixing in the QC-VECSEL. The stability of the device under variable optical feedback conditions is also studied. Any mechanical instabilities of the external cavity (such as vibrations of the output coupler), are enhanced due to feedback and result in low-frequency oscillations of the terminal voltage. The work reveals how the self-mixing response differs for the QC-VECSEL architecture, informs other systems in which optical feedback is unavoidable, and paves the way for QC-VECSEL self-mixing applications.

Infrared scattering-type near-field optical microscopy, IR s-SNOM, and its broadband variant, nano-FTIR, are pioneering, flagship techniques for their ability to provide molecular identification and material optical property information at a spatial resolution well below the far-field diffraction limit, typically less than 25 nm. While s-SNOM and nano-FTIR instrumentation and data analysis have been discussed previously, there is a lack of information regarding experimental parameters for the practitioner, especially in the context of previously developed frameworks. Like conventional FTIR spectroscopy, the critical component of a nano-FTIR instrument is an interferometer. However, unlike FTIR spectroscopy, the resulting interference patterns or interferograms are typically asymmetric. Here, we unambiguously describe the origins of asymmetric interferograms recorded with nano-FTIR instruments, give a detailed analysis of potential artifacts, and recommend optimal instrument settings as well as data analysis parameters.

An ultra-broadband beam splitter arrangement, with a spectral amplitude response that is over seven orders-of-magnitude more uniform than broadband, multi-layer dielectric beam splitters, can be created by the combination of multiple Fresnel events on an uncoated, optical flat when used at a specific angle-of-incidence. This beam splitter arrangement produces three, spectral copies of the original, two of which have identical spectral phase. In this manuscript we derive the precise angle at which this maximally flat spectral amplitude response occurs for any material and present this angle’s material and polarization dependence.

SignificanceOver the past decade, machine learning (ML) algorithms have rapidly become much more widespread for numerous biomedical applications, including the diagnosis and categorization of disease and injury.AimHere, we seek to characterize the recent growth of ML techniques that use imaging data to classify burn wound severity and report on the accuracies of different approaches.ApproachTo this end, we present a comprehensive literature review of preclinical and clinical studies using ML techniques to classify the severity of burn wounds.ResultsThe majority of these reports used digital color photographs as input data to the classification algorithms, but recently there has been an increasing prevalence of the use of ML approaches using input data from more advanced optical imaging modalities (e.g., multispectral and hyperspectral imaging, optical coherence tomography), in addition to multimodal techniques. The classification accuracy of the different methods is reported; it typically ranges from ∼70% to 90% relative to the current gold standard of clinical judgment.ConclusionsThe field would benefit from systematic analysis of the effects of different input data modalities, training/testing sets, and ML classifiers on the reported accuracy. Despite this current limitation, ML-based algorithms show significant promise for assisting in objectively classifying burn wound severity.

SignificanceX-ray-induced acoustic computed tomography (XACT) offers a promising approach to biomedical imaging, leveraging X-ray absorption contrast. It overcomes the shortages of traditional X-ray, allowing for more advanced medical imaging.AimThe review focuses on the significance and draws onto the potential applications of XACT to demonstrate it as an innovative imaging technique.ApproachThis review navigates the expanding landscape of XACT imaging within the biomedical sphere. Integral topics addressed encompass the refinement of imaging systems and the advancement in image reconstruction algorithms. The review particularly emphasizes XACT's significant biomedical applications.ResultsKey uses, such as breast imaging, bone density maps for osteoporosis, and X-ray molecular imaging, are highlighted to demonstrate the capability of XACT. A unique niche for XACT imaging is its application in in vivo dosimetry during radiotherapy, which has been validated on patients.ConclusionsBecause of its unique property, XACT has great potential in biomedicine and non-destructive testing. We conclude by casting light on potential future avenues in this promising domain.

The rapid development of silicon photonics inspired the emergence of on‐chip geometric optics. As one of the most crucial elements, waveguide‐lenses have attracted much attention. Nevertheless, waveguide‐lenses often suffer from large chromatism due to the strong waveguide dispersion, especially for the cases with multiple guided‐modes. In this paper, achromatic waveguide‐lenses available for multimode photonics are proposed and are further utilized for realizing multimode spot size converters (MSSCs) as an example. The present MSSC shows low excess losses < 0.4 dB and low inter‐mode crosstalks <−14 dB within an ultra‐broad bandwidth of 1450–1650 nm, which is realized for the first time by comprising a positive waveguide‐lens and a negative waveguide‐lens. In addition, the present MSSC is applied successfully for realizing high‐performance multimode waveguide corner‐bends. To the best of the knowledge, the proposed MSSC is the unique one with an ultra‐compact footprint and the largest bandwidth for low crosstalks as well as low losses, indicating that on‐chip geometric optics potentially provides a new perspective for on‐chip light manipulation desired in various applications. [ABSTRACT FROM AUTHOR]

The recently reported compactified hyperboloidal method has found wide use in the numerical computation of quasinormal modes, with implications for fields as diverse as gravitational physics and optics. We extend this intrinsically relativistic method into the non-relativistic domain, demonstrating its use to calculate the quasinormal modes of the Schrodinger equation and solve related bound-state problems. We also describe how to further generalize this method, offering a perspective on the importance of non-relativistic quasinormal modes for the programme of black hole spectroscopy. [ABSTRACT FROM AUTHOR]

Entangled multiphoton sources are essential for both fundamental tests of quantum foundations and building blocks of contemporary optical quantum technologies. While efforts over the past three decades have focused on creating multiphoton entanglement through multiplexing existing biphoton sources with linear optics and postselections, our work presents a groundbreaking approach. We observe genuine continuous-mode time-energy-entangled W-class triphotons with an unprecedented production rate directly generated through spontaneous six-wave mixing (SSWM) in a four-level triple-Λ atomic vapor cell. Using electromagnetically induced transparency and coherence control, our SSWM scheme allows versatile narrowband triphoton generation with advantageous properties, including long temporal coherence and controllable waveforms. This advancement is ideal for applications like long-distance quantum communications and information processing, bridging single photons and neutral atoms. Most importantly, our work establishes a reliable and efficient genuine triphoton source, facilitating accessible research on multiphoton entanglement. [ABSTRACT FROM AUTHOR]

Among the fascinating phenomena observed in two-dimensional (2D) magnets, the magneto-exciton effect stands out as a pivotal link between optics and magnetism. Although the excitonic effect has been revealed and exhibits a considerable correlation with the spin structures in certain 2D magnets, the underlying mechanism of the magneto-exciton effect remains underexplored, especially under high magnetic fields. Here we perform a systematic investigation of the spin-exciton coupling in 2D antiferromagnetic NiPS3 under high magnetic fields. When an in-plane magnetic field is applied, the exceptional sharp excitonic emission at ~1.4756 eV exhibits a Zeeman-like splitting with g ≈ 2.0, experimentally identifying the exciton as an excitation of dominant triplet-singlet character. By examining the polarization of excitonic emission and simulating the spin evolution, we further verify the correlation between excitonic emission and Néel vector in NiPS3. Our work elucidates the mechanism behind the spin-exciton coupling in NiPS3 and establishes a strategy for optically probing the spin evolutions in 2D magnets. NiPS3, a van der Waals antiferromagnet exhibits exciton emission with a very sharp linewidth. The exact origin of this is has been a subject of active debate. Here, Wang et al study the behavior of this sharp exciton peak under applied magnetic fields, and find a Zeeman-like splitting, indicating the exciton has triplet-singlet character. [ABSTRACT FROM AUTHOR]

This paper presents a microscopy technique that can perform snapshot depth resolved optical imaging in the same manner as A-scan in ultrasound imaging and optical coherence tomography. In this technique, a laser line along the axial dimension is used to illuminate a sample to create a fluorescent line object. By transforming the line object along the axial dimension (Z) to a ring image on the lateral dimensions (X-Y) using a full cone mirror, common optics can be used to relay and acquire the ring image precisely. Then, by converting half of the ring image back to a line image using a half cone mirror, the opening side of the half cone mirror allows the line image, which contains the full depth resolved information of the line object, to be taken in one snapshot. This eliminates the requirement of axial scanning in traditional depth resolved imaging techniques such as confocal microscopy to obtain the same information. The technique is demonstrated by imaging fluorescent microspheres of different diameters. This technique offers a simple alternative to traditional depth resolved imaging techniques such as confocal microscopy and light sheet microscopy. It is particularly useful in imaging samples with multiple layers in which multiple A-scans or a few B-scans are sufficient to represent the entire sample. [ABSTRACT FROM AUTHOR]

High‐energy, few‐cycle laser pulses are essential for numerous applications in the fields of ultrafast optics and strong‐field physics, due to their ultrafast temporal resolution and high peak intensity. In this work, different from the traditional hollow‐core fibers and multiple thin solid plates, the generation of an octave‐spanning supercontinuum broadening is demonstrated by utilizing multiple ultrathin liquid films (MTLFs) as the nonlinear media. The continuum covers a range from 380 to 1050 nm, corresponding to a Fourier transform limit pulse width of 2.5 fs when 35 fs Ti: sapphire laser pulse is applied on the MTLFs. The output pulses are compressed to 3.9 fs by employing chirped mirrors. Furthermore, a continuous high‐order harmonic spectrum up to the 33rd order is realized by subjecting the compressed laser pulses to interact with Kr gas. The utilization of flowing liquid films eliminates permanent optical damage and enables wider and stronger spectrum broadening. Therefore, this MTLFs scheme provides new solutions for the generation of highly efficient supercontinuum and nonlinear pulse compression, with potential applications in the fields of strong‐field physics and attosecond science. [ABSTRACT FROM AUTHOR]

Spatiotemporal structured light has opened up new avenues for optics and photonics. Current spatiotemporal manipulation of light mostly relies on phase-only devices such as liquid crystal spatial light modulators to generate spatiotemporal optical fields with unique photonic properties. However, simultaneous manipulation of both amplitude and phase of the complex field for the spatiotemporal light is still lacking, limiting the diversity and richness of achievable photonic properties. In this work, a simple and versatile spatiotemporal holographic method that can arbitrarily sculpt the spatiotemporal light is presented. The capabilities of this simple yet powerful method are demonstrated through the generation of fundamental and higher-order spatiotemporal Bessel wavepackets, spatiotemporal crystal-like and quasi-crystal-like structures, and spatiotemporal flat-top wavepackets. Fully customizable spatiotemporal wavepackets will find broader application in investigating the dynamics of spatiotemporal fields and interactions between ultrafast spatiotemporal pulses and matters, unveiling previously hidden light-matter interactions and unlocking breakthroughs in photonics and beyond. The authors showcase a spatiotemporal holographic method that can arbitrarily sculpt spatiotemporal light by generating various spatiotemporal wavepackets. The ability to deploy these fully customizable wavepackets opens up exciting avenues for their use in broader applications. [ABSTRACT FROM AUTHOR]

Materials that provide dynamically tunable infrared (IR) response are important for many applications, including active camouflage and thermal management. However, current IR-tunable systems often exhibit limitations in mechanical properties or practicality of their tuning modalities, or require complex and costly fabrication methods. An additional challenge relates to providing compatibility between different spectral channels, such as allowing an object to be reversibly concealed in the IR without making it appear in the visible range. Here, we demonstrate that conducting polymer-cellulose papers, fabricated through a simple and cheap approach, can overcome such challenges. The papers exhibit IR properties that can be electrochemically tuned with large modulation (absolute emissivity modulation of 0.4) while maintaining largely constant response in the visible range. Owing to high ionic and electrical conductivity, the tuning of the top surface can be performed electrochemically from the other side of the paper even at tens of micrometer thicknesses, removing the need for overlaying electrode and electrolyte in the optical beam path. These features enabled a series of electrically tunable IR devices, where we focus on demonstrating dynamic radiative coolers, thermal camouflage, anti-counterfeiting tags, and grayscale IR displays. The conducting polymer-cellulose papers are sustainable, cheap, flexible and mechanically robust, providing a versatile materials platform for active and adaptive IR optoelectronic devices. [ABSTRACT FROM AUTHOR]

Manipulation of wavefront lies at the core of next‐generation information technologies. Compared to metal and dielectric metasurfaces, atomic 2D materials exhibit excellent prospects toward fulfilling ultra‐thin thickness requirements in flat optics in wavefront shaping, with thickness much smaller than those of traditional bulky devices. However, phase manipulation by light propagating through atomic 2D materials is suppressed due to its sub‐nanometer thickness. Here, an approach is reported to realize reflection phase singularities by establishing a zero‐reflection point in a monolayer MoS2‐based multilayer system, which broadens topological study beyond polarization singularity. This is achieved through the creation of a multilayer Fabry‐Perot‐type interference, and a pronounced phase change in the reflected light is realized due to the high absorption of monolayer MoS2 in the studied wavelength range. As an application, a rapid, sensitive, and label‐free detection of SARS‐CoV‐2 (2019‐nCov) antigen is demonstrated with a detection limit of 10−12 M L−1 (62 pg ml−1) by using monolayer MoS2 based optical biosensor. In addition to offering a comprehensive study in phase singularity, efficient wavefront engineering based on the reflective system using materials is presented with atomic thickness which may greatly simplify optical architecture in flat optics, and promote its development toward compactness and integrated functions. [ABSTRACT FROM AUTHOR]

Introduction Musculoskeletal injuries (MSKIs) among active duty soldiers result in more than 10 million limited duty days each year and account for more than 70% of the medically nondeployable population. Overuse injuries in lower limbs from running, foot marching long distances with heavy loads, and lifting heavy objects are the most common types of injuries in the military. Physical training and rehabilitation exercises for greater resiliency through aerobic, muscle strength, endurance, and agility conditioning programs can prevent or reduce the effects of MSKIs if Soldiers adhere to proper biomechanics and training techniques. We are introducing a three-dimensional (3D) camera-based platform for Optical Screening and Conditioning for Injury Resilience (OSCIR) that is designed to identify and correct high-risk movement patterns based on quantifiable biomechanical measurements in clinical or field settings. Our goal is to improve resilience to MSKI by offering greater access to quality of movement skills in warfighters through an autonomous device that can be used in Sports Medicine and Reconditioning Team (SMART) clinics and High-Intensity Tactical Training (HITT) sites. Materials and Methods OSCIR fuses four pairs of Kinect Azure cameras into a concise footprint to achieve suitable sampling rates and an unobstructed field of view for accurate dynamic movement tracking using a custom point cloud solution. We designed a unique multistage 3D joint tracking algorithm architecture to methodically isolate the human body point cloud from the background, identify individual limb segments, and perform iterative joint optimization at the global and local joint levels. We evaluated the feasibility of our prototype system among N  = 12 control participants (6 M/6 F; 21-37 years) in compliance with the Western Institutional Review Board (Tracking #20225920, approved on November 4, 2022). Five task-specific MSKI outcome metrics identified by end-user physical therapists and athletic trainers as indicators for movement quality were assessed across 7 lower-extremity exercises derived from standardized MSK assessment/conditioning batteries used in the military. Data were recorded concurrently by OSCIR and a reference standard Vicon motion capture system for validating system accuracy. Results Task-specific MSKI indicators for knee flexion and hip flexion range of motion achieved an average error of 4.05 ± 2.34°, while 3D position-based postural outcomes of left-right foot distance, left-right hand distance, and step length obtained mean absolute errors of 2.58 ± 2.30 cm. Results support the feasibility of our system in achieving outcomes that are comparable to currently accepted laboratory standards. Conclusions Our study describes the integration process for a 3D camera-based clinical system for MSKI conditioning and rehabilitation. The impact of our system will enable key stakeholders in the military to manage MSKIs in warfighters by automating key assessment and rehabilitation test batteries; making tests more readily accessible, and interpretations more accurate by providing objective biomechanical measures. OSCIR is undergoing turn-key design features to serve as a screening tool for warfighters to readily assess susceptibility to MSKI or as a training platform to help guide exercise techniques to achieve resiliency against future injuries. [ABSTRACT FROM AUTHOR]

Introduction Achieving simultaneous cerebral blood flow (CBF) and oxygenation measures, specifically for point-of-care injury monitoring in prolonged field care, requires the implementation of appropriate methodologies and advanced medical device design, development, and evaluation. The near-infrared spectroscopy (NIRS) method measures the absorbance of light whose attenuation is related to cerebral blood volume and oxygenation. By contrast, diffuse correlation spectroscopy (DCS) allows continuous noninvasive monitoring of microvascular blood flow by directly measuring the degree of light scattering because of red blood cell (RBC) movement in tissue capillaries. Hence, this study utilizes these two optical approaches (DCS–NIRS) to obtain a more complete hemodynamic monitoring by providing cerebral microvascular blood flow, hemoglobin oxygenation and deoxygenation in hemorrhage, and hypoxia-induced injuries. Materials and Methods Piglet models of hemorrhage and hypoxia-induced brain injury were used with DCS and NIRS sensors placed over the preorbital to temporal skull regions. To induce hemorrhagic shock, up to 70% of the animal's total blood volume was withdrawn through graded hemorrhage serially via a syringe from a femoral artery cannula in 10 mL/kg aliquots over 1 minute every 10 minutes. A second group of animals was subjected to hypoxia for ∼1 hour through graded hypoxia by serial titration from normoxic fraction inspired oxygen of 21% to hypoxic fraction inspired oxygen of 6%. A subset of animals served as sham-controls undergoing anesthesia, instrumentation, and ventilation as the injury groups, yet experiencing no blood loss or hypoxia. Results We first investigated the relationship between hemorrhagic shock and no shock by using measured biomarkers, including blood flow index from DCS associated with CBF and oxygenated (HbO) and de-oxygenated hemoglobin from NIRS. The statistical analysis revealed a significant difference between no shock and hemorrhagic shock (P  < .01). The HbO decreased with each blood loss as expected, yet the de-oxygenated hemoglobin was slightly changed. During hypoxia-induced global hypoxic–ischemic injury tests, the CBF results from graded hypoxia were consistent with the response previously measured during hemorrhagic shock. Moreover, HbO decreased when the animal was hypoxic, as expected. A statistical analysis was also conducted to compare the results with those of the sham controls. Conclusions There is a consistency in blood flow measures in both injury mechanisms (hemorrhagic shock and hypoxia), which is significant as the new prototype system provides similar measures and trends for each brain injury type, suggesting that the optical system can be used in response to different injury mechanisms. Notably, the results support the idea that this optical system can probe the hemodynamic status of local cerebral cortical tissue and provide insight into the underlying changes of cerebral tissue perfusion at the microvascular level. These measurement capabilities can improve shock identification and monitoring of medical management of injuries, particularly hemorrhagic shock, in prolonged field care. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) simulation is a vital tool for planning SAR missions, interpreting SAR images, and extracting valuable information. SAR imaging is essential for analyzing sea scenes, and the accuracy of sea surface and scattering models is crucial for effective SAR simulations. Traditional methods typically employ empirical formulas to fit sea surface scattering, which are not closely aligned with the principles of electromagnetic scattering. This paper introduces a novel approach by constructing multiple sea surface models based on the Pierson–Moskowitz (P-M) sea spectrum, integrated with the stereo wave observation projection (SWOP) expansion function to thoroughly account for the influence of wave fluctuation characteristics on radar scattering. Utilizing the shooting and bouncing ray-physical optics (SBR-PO) method, which adheres to the principles of electromagnetic scattering, this study not only analyzes sea surface scattering characteristics under various sea conditions but also facilitates the computation of scattering coupling between multiple targets. By constructing detailed scattering distribution data, the method achieves high-precision SAR simulation results. The scattering model developed using the SBR-PO method provides a more nuanced description of sea surface scenes compared to traditional methods, achieving an optimal balance between efficiency and accuracy, thus significantly enhancing sea surface SAR imaging simulations. [ABSTRACT FROM AUTHOR]

Delaying an electromagnetic (EM) wave pulse on a thin screen for a significant time before releasing it is highly desired in many applications, such as optical camouflage, information storage, and wave–matter interaction boosting. However, available approaches to achieve this goal either require thick and complex systems or suffer from low efficiencies and a short delay time. This paper proposes an ultra-thin meta-platform that can significantly delay an EM-wave pulse after reflection. Specifically, our meta-platform consists of three meta-surfaces integrated together, of which two are responsible for efficiently coupling incident EM-wave pulse into surface waves (SWs) and vice versa, and the third one supports SWs exhibiting significantly reduced group velocity. We employ theoretical model analyses, full-wave simulations, and microwave experiments to validate the proposed concept. Our experiments demonstrate a 13 ns delay of an EM pulse centered at 12.975 GHz, enabled by a λ/8-thick and 38-λ-long meta-device with an efficiency of 32% (or 70%) with (or without) material loss taken into account. A larger delay time can be enabled by devices with larger sizes considering that the SWs group velocity of our device can be further reduced via dispersion engineering. These findings establish a new road for delaying an EM-wave pulse with ultra-thin screens, which may lead to many promising applications in integration optics. [ABSTRACT FROM AUTHOR]

Thomas Hardy uses the painterly triptych of foreground, middle distance, and background in his narrative structures. These developments can be read as spatial scrolls. Their design recalls the narrative chronotope described by Mikhail Bakhtin. While the scroll is simple in form, Hardy deploys it complexly to delineate location, perspective, value, and identity. Many illustrations from his poetry such as "Wessex Heights," "The Pedigree," and "Poems of 1912–13" are examined. A Pair of Blue Eyes (1873), Return of the Native (1873), Tess of the d'Urbervilles (1891), Jude the Obscure (1895) and other novels use the scroll. The scroll design mediates the narrative interplay of optics and options in Hardy's work. The construct of Wessex is Hardy's most elaborate narrative and his most elaborate scroll. [ABSTRACT FROM AUTHOR]

We present calculations of interferograms (interference patterns) of one or multiple spiral phase plates that would be observed with a perfect crystal neutron interferometer of Mach–Zehnder type. A spiral phase plate (SPP) in one of the two coherent beam paths produces a twist in the phase front and thus a vortex beam with intrinsic angular momentum, which in the case of neutrons should be observed as a characteristic interference pattern that appears complementary to each other in both detectors behind the interferometer. Adding additional SPPs in one beam path of the interferometer yield interference patterns similar to that of a single SPP but only due to the cumulative step height. All simulated interferograms have been calculated on the basis of dynamical neutron diffraction without any assumption of a neutron orbital angular momentum and show very convincing agreement with experimental results from the literature, see e.g. (C. W. Clark, R. Barankov, M. G. Huber, M. Arif, D. G. Cory, and D. A. Pushin, "Controlling neutron orbital angular momentum," Nature, vol. 525, pp. 504–506, 2015). In particular, this clarifies, that the cited experiments do not give evidence of the quantization of interactions caused by a twist of the phase front of a neutron wave in the interferometer and thus no evidence for the effect of a neutron orbital angular momentum. [ABSTRACT FROM AUTHOR]

A 1D imaging soft X‐ray spectrometer installed on the small quantum systems (SQS) scientific instrument of the European XFEL is described. It uses movable cylindrical constant‐line‐spacing gratings in the Rowland configuration for energy dispersion in the vertical plane, and Wolter optics for simultaneous 1D imaging of the source in the horizontal plane. The soft X‐ray fluorescence spectro‐imaging capability will be exploited in pump–probe measurements and in investigations of propagation effects and other nonlinear phenomena. [ABSTRACT FROM AUTHOR]

In situ wavefront sensing plays a critical role in the delivery of high‐quality beams for X‐ray experiments. X‐ray speckle‐based techniques stand out among other in situ techniques for their easy experimental setup and various data acquisition modes. Although X‐ray speckle‐based techniques have been under development for more than a decade, there are still no user‐friendly software packages for new researchers to begin with. Here, we present an open‐source Python package, spexwavepy, for X‐ray wavefront sensing using speckle‐based techniques. This Python package covers a variety of X‐ray speckle‐based techniques, provides plenty of examples with real experimental data and offers detailed online documentation for users. We hope it can help new researchers learn and apply the speckle‐based techniques for X‐ray wavefront sensing to synchrotron radiation and X‐ray free‐electron laser beamlines. [ABSTRACT FROM AUTHOR]

A state‐of‐the‐art multilayer deposition system with a 4200 mm‐long linear substrate translator housed within an ultra‐high vacuum chamber has been developed. This instrument is engineered to produce single and multilayer coatings, accommodating mirrors up to 2000 mm in length through the utilization of eight rectangular cathodes. To ensure the quality and reliability of the coatings, the system incorporates various diagnostic tools for in situ thickness uniformity and stress measurement. Furthermore, the system features an annealing process capable of heating up to 700°C within the load‐lock chamber. The entire operation, including pump down, deposition and venting processes, is automated through user‐friendly software. In addition, all essential log data, power of sputtering source, working pressure and motion positions are automatically stored for comprehensive data analysis. Preliminary commissioning results demonstrate excellent lateral film thickness uniformity, achieving 0.26% along the translation direction over 1500 mm in dynamic mode. The multilayer deposition system is poised for use in fabricating periodic, lateral‐graded and depth‐graded multilayers, specifically catering to the beamlines for diverse scientific applications at Diamond Light Source. [ABSTRACT FROM AUTHOR]

Pictorial awareness is addressed through experimental phenomenology involving over 90 naïve participants. Since one can't look at the "same" picture twice the study uses one-shot trials. The participant's fascination for the duration of a session is held through the artistic principle of theme and variation. Six variations focus on the theme of pictorial geometry, both two-dimensional and three-dimensional. Major findings are: Idiosyncratic deviations from veridical are huge as compared to common textbook "effects." Observers wield arbitrary heuristics for tasks that are "formally related." The assumption of a common formal framework is apparently unsound. The notion of "inverse optics" is misleading. A fair fraction of the population appears to lack monocular stereopsis as intuitive awareness. It suggests an as-yet unrecognized, but perhaps common variety of aphantasia. [ABSTRACT FROM AUTHOR]

Specific domains of modern life—social, ecological, legal—involve distinct issues of justice that often lead to a single-focused political-philosophical engagement with justice. Such engagements, argues Marianna Papastephanou, risk turning issues of justice that lie beyond the adopted perspective into discursive injustices (i.e. of silencing the Other's voice) and condemning them to invisibility. To address this risk, Papastephanou proposes a stereoscopic approach that better illuminates the many facets of justice and, concomitantly, the many instances of injustice that escape the dominant political-philosophical perspectives on justice. In the present article, I discuss Papastephanou's theory of a stereoscopic approach to justice along with Ernesto Laclau and Chantal Mouffe's discourse theory and notion of "nodal points." I suggest that the synergy between the two approaches enhances their efficacy: Papastephanou's theorization concretizes the implications of establishing nodal points, which, in turn, reveal how the reduction of justice to one of its facets occurs at the discursive level. Enriched by Papastephanou's theorization, discourse theory makes more visible how a stereoscopic approach to justice can unveil discursive injustices of selective and partial outlooks on (in)justice. [ABSTRACT FROM AUTHOR]

Monte Carlo simulation techniques have become the quintessence and a pivotal nexus of inquiry in the realm of simulating photon movement within biological fabrics. Through the stochastic sampling of tissue archetypes delineated by explicit optical characteristics, Monte Carlo simulations possess the theoretical capacity to render unparalleled accuracy in the depiction of exceedingly intricate phenomena. Nonetheless, the quintessential challenge associated with Monte Carlo simulation methodologies resides in their extended computational duration, which significantly impedes the refinement of their precision. Consequently, this discourse is specifically dedicated to exploring innovations in strategies and technologies aimed at expediting Monte Carlo simulations. It delves into the foundational concepts of various acceleration tactics, evaluates these strategies concerning their speed, accuracy, and practicality, and amalgamates a comprehensive overview and critique of acceleration methodologies for Monte Carlo simulations. Ultimately, the discourse envisages prospective trajectories for the employment of Monte Carlo techniques within the domain of tissue optics. [ABSTRACT FROM AUTHOR]

The integrable Sasa–Satsuma (SS) equation, a higher-order Nonlinear Schrödinger (NLS)-type model, has important applications in the field of optics. In this study, we present a generalized SS equation with variable coefficients derived from a mixed spectral problem, abbreviated as vcmsgSSE, and construct its N-soliton solution using the Riemann–Hilbert (RH) method. First, we provide the Lax pair associated with the vcmsgSSE and perform a spectral analysis on it, which allows us to derive a solvable RH problem. Then, by solving this RH problem we construct an explicit expression for N-soliton solution of the vcmsgSSE. Finally, under a special reduction, we obtain the specific one-soliton solution and two-soliton solution of the vcmsgSSE, and use them to illustrate graphically the N-soliton solution with varying amplitude and/or varying velocity corresponds to the physical background of non-uniform medium assumed by the vcmsgSSE. [ABSTRACT FROM AUTHOR]

Fractional‐order ray equations and fractional Duffing‐van der Pol oscillator equations are relationships utilized as a reliable means of modeling some phenomena in optics and engineering. The main motivation of this study is to introduce a new hybrid technique utilizing Chelyshkov wavelets and least squares‐support vector regression (LS‐SVR) for determining the approximate solution of fractional ray equations and fractional Duffing‐van der Pol oscillator equations (D‐v POEs). With the help of the Riemann‐Liouville operator for Chelyshkov wavelets and LS‐SVR (called Chw‐Ls‐SVR), the mentioned problems transform into systems of algebraic equations. The convergence analysis is discussed. Finally, the numerical results are proposed and compared with some schemes to display the capability of the numerical technique proposed here. [ABSTRACT FROM AUTHOR]

In field of diffuse optics for biomedical applications, the spatial sensitivity (SS) is a key parameter to evaluate or optimize the adopted modalities, such as penetration depth, signal-to-noise ratio as well as sensor distribution. Nevertheless, SS is usually estimated via computer simulations (e.g., photon Monte Carlo simulation), rather than being quantified experimentally, due to the technical difficulty. In this study, we report the experimental measurement and visualization of optical SS through combination of acoustic radiation force (ARF) and the scanning diffuse correlation spectroscopy (DCS). By spatially varying the location of ARF focal spot within liquid phantom, the enhanced particle flow, which represents the most spatial sensitive location, was identified by DCS. The experimental outcomes were cross-validated with the photon Monte Carlo simulation, thus demonstrating its accuracy, feasibility, and potential for guiding clinical usage. [ABSTRACT FROM AUTHOR]

This study introduces a laser scattering system to protect a low-speed aircraft. Scattering was selected to reduce the laser's intensity targeting the sensor of an aircraft and simultaneously maintaining the functionality of aircraft optics. Mie scattering, known for effectively decreasing short-wave infrared light, was employed by utilizing water aerosols having a diameter of 1 to 5 μm. Experimental results regarding the decrease of the laser intensity via scattering confirmed that the theoretical and experimental values resulted in a similar decrease rate under static conditions. To validate the theoretical values, the path length, which the laser passing through water aerosols, was changed. To assess the system's feasibility in flow conditions, a low-speed wind tunnel was employed to generate two flow speeds: 5.5 m/s and 17.6 m/s. Remarkably, the reduction of laser intensity was only affected by the path length, and was somewhat unaffected regardless of flow speed and the uniformity of the flow, only to the path length. In all cases, the initial laser intensity was set to 10 mW. Under static conditions, the intensity dropped to 8.21 mW, showing a decrease of 17.9%. In flow conditions of 5.5 m/s, 17.6 m/s, and in distorted flow, the laser intensity decreased by 18.3%, 18.1%, and 18% respectively. As a preliminary study, these results demonstrate the system's capability to protect a low-speed aircraft targeted by lasers even under dynamic flow conditions, may suggest a possibility of providing a practical defence solution. [ABSTRACT FROM AUTHOR]

Fluorescence microscopy possesses the advantages of high resolution, high sensitivity, molecular specificity and noninvasiveness, providing an important tool in life science research. The multifocal array and 3D structured light are two kinds of important light fields that are often used in scanning fluorescence microscopy systems and wide-field fluorescence microscopy systems. However, traditional methods for generating multifocal arrays and 3D structured light illumination rely on various bulk optical components, making it challenging to achieve compact optical systems. Besides, generating these two types of illumination typically requires two separate and independent optical systems, hindering the integration of different types of fluorescence microscopy systems. Here, a dielectric metasurface is proposed that can achieve the switching between multifocal arrays and 3D structured light through polarization state modulation, greatly simplifying the illumination optics of fluorescence microscopy systems and facilitating the integration of different types of fluorescence microscopy systems. [ABSTRACT FROM AUTHOR]

In this work, we studied the x‐ray energy dependence of x‐ray beam diameter focused by polycapillary optics. A quantitative beam diameter–energy relation enables more accurate estimation of the element‐specific interrogation area of a sample using the compositional maps produced by a micro‐XRF system. This improves upon our ability to visualize individual beam‐diameter sized mineral grains and in turn directly benefits Planetary Instrument for X‐ray Lithochemistry (PIXL) analyses of martian soil in addition to benefitting other micro‐focused x‐ray fluorescence (XRF) systems. The spatial distribution of an array of characteristic XRF emission lines was measured by sampling via a knife‐edge approach with small motor stepping of the beam across target edges. Data taken as part of this effort, from the Planetary Flight Model (PFM), were limited to only seven beam energies corresponding to the elements Ni, Cu, Se, Ta, Au, Ti and Ba. Hence, we conducted additional analysis using JPL's lab‐based breadboard (LBB) micro‐XRF system, a system that emulates PIXL's functionality where we measured beam diameter corresponding to 18 elements: Na, Mg, Al, Si, Cl, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Se, Sr and Mo. The experimental results were also compared with Monte Carlo simulations. The beam diameter (y)–energy (x) relation that we obtained for LBB was y = 185.79 exp(−0.078x) whose exponential component was then used to get a more accurate relation for the PFM even with the limited data set: y = 227.53 exp(−0.078x). The difference in the two coefficients for the PFM and LBB stems mainly from the difference in the polycapillary optic design, and this work establishes x‐ray beam diameter versus energy relation quantitatively for both the systems. [ABSTRACT FROM AUTHOR]

Metasurfaces are sub‐wavelength nanostructures with the potential to overcome the limitations of traditional optics. Existing dielectric metasurfaces, however, are often limited to geometric primitives, which hamper their application in emergent hybrid metasurfaces. Here, a simple fabrication scheme for non‐primitive metasurfaces that addresses this limitation is introduced. Due to their broken out‐of‐plane symmetry, these nanostructures provide a new dimension in the design space. Taking inspiration from bio‐photonic systems in nature, using these elements complex hybrid metasurfaces are designed that encompass an ordered and a disordered phase. The capabilities of this hybrid optical systems are illustrated by generating configurable structural colors with extra ordinary resolution. Furthermore, the local control of light over a broad bandwidth is demonstrated and a maximum coupling efficiency of more than 97% is achieved. [ABSTRACT FROM AUTHOR]

Ultrashort light pulses have strong research and application values, while nonlinear inverse Thomson scattering has been considered as a unique source of zepto-yoctosecond pulses. Here, the mechanism of nonlinear inverse Thomson scattering of a high-energy electron colliding with a tightly focused intense laser pulse is investigated through numerical simulation. The time-compression effect was proposed to explain the origin of ultrashort pulses and the nonlinear phenomenon of electron radiation in the time–space joint distribution. It is found that the time scale of electron radiation is orders of magnitude shorter than that of electron motion, and the increases in laser intensity and electron initial energy will result in stronger and shorter pulses. Yoctosecond pulses can be generated by a laser pulse with an intensity of 1.384 × 10 20   W / c m 2 and an electron with an initial energy of 51.1   M e V . These results provide theoretical and numerical basis for generating shorter light pulses. [ABSTRACT FROM AUTHOR]

This study aimed to establish a virtual cross cylinder method to calculate the total corneal astigmatism by combining the anterior and posterior corneal astigmatism on the secondary principal plane of the cornea based on Gaussian optics. The meridian with the least refractive power, namely, the flattest meridian of the virtual cross cylinder of a ± 0.5 × C diopter, is set as the reference meridian, and the power (F) at an angle of φ between an arbitrary meridian and the reference meridian is defined as F(φ) = − 0.5 × C × cos2φ. The magnitude and axis of the total corneal astigmatism were calculated by applying trigonometric functions and the atan2 function based on the combination of the virtual cross cylinders of the anterior corneal astigmatism and the posterior corneal astigmatism. To verify the performance of the virtual cross cylinder method, a verification experiment with two Jackson cross cylinders and a lensmeter was performed, and the measured and calculated values were compared. The limit of the natural domain of the arctangent function is circumvented by using the atan2 function. The magnitude and axis of the total corneal astigmatism are determined through generalized mathematical expressions. The verification experiment results showed good agreement between the measured and calculated values. Compared to the vector analysis method, the virtual cross cylinder method is mathematically sound and straightforward. A novel technique for calculating total corneal astigmatism, the virtual cross cylinder method, was developed and verified. [ABSTRACT FROM AUTHOR]

Recent advances in metadevices, featuring complex subwavelength metastructures, have dramatically transformed the control and manipulation of electromagnetic waves. However, the inherently narrow operational bandwidth of these devices, stemming from their wavelength‐specific meta‐atoms, restricts their application in rapidly advancing fields such as the Internet of Things and advanced intelligent systems. Here, a novel hyperband synergistic metadevice is introduced, realized through a comprehensive multi‐scale meta‐atom architecture. The complementary metal‐oxide‐semiconductor (CMOS)‐compatible prototype integrates the distinct properties of double‐walled carbon nanotubes with advanced interlayer and intralayer coupling mechanisms, coherently combining nanoscale, microscale, and macroscale meta‐atoms. This prototype is thus adept at operating across a wide electromagnetic spectrum, spanning from the centimeter‐wavelength microwave band to the hundred nanometer‐wavelength visible and infrared optical band. Significantly, this singular device synergistically delivers three critical functionalities: selective microwave absorption, efficient terahertz beam steering, and enhanced optical transparency. These result signifies a breakthrough in hyperband electromagnetic device engineering, leading to compact, versatile, intelligent electromagnetic platforms. [ABSTRACT FROM AUTHOR]

Color centers in wide band-gap semiconductors, which have superior quantum properties even at room temperature and atmospheric pressure, have been actively applied to quantum sensing devices. Characterizing the quantum properties of the color centers in the semiconductor materials and ensuring that these properties are uniform over a wide area are key issues for developing quantum sensing devices based on color centers. In this article, we have developed an optics design protocol optimized for evaluating the quantum properties of color centers and have used this design approach to develop a new microscopy system called columnar excitation fluorescence microscope (CEFM). The essence of this system is to maximize the amount of fluorescence detection of polarized color centers, which is achieved by large-volume and uniform laser excitation along the sample thickness with sufficient laser power density. This laser excitation technique prevents undesirable transitions to undesirable charge states and undesirable light, such as unpolarized color center fluorescence, while significantly increasing the color center fluorescence. This feature enables fast measurements with a high signal-to-noise ratio, making it possible to evaluate the spatial distribution of quantum properties across an entire mm-size sample without using a darkroom, which is difficult with typical confocal microscope systems. [ABSTRACT FROM AUTHOR]

Soliton pulsations are ubiquitous feature of non‐stationary soliton dynamics in mode‐locked lasers and many other physical systems. To overcome difficulties related to a huge amount of necessary computations and low efficiency of traditional numerical methods in modeling the evolution of non‐stationary solitons, a two‐parallel bidirectional long short‐term memory recurrent neural network (TP‐Bi_LSTM RNN) is proposed, with the main objective to predict dynamics of vector‐soliton pulsations (VSPs) in various complex states, whose real‐time dynamics is verified by experiments. For two examples, viz., single‐ and bi‐periodic VSPs, with period‐21 and a combination of period‐3 and period‐43, the prediction results are better than provided by direct simulations – namely, deviations produced by the TP‐Bi_LSTM RNN results are 36% and 18% less than those provided by the simulations, respectively. This means that predicted results provided by the neural network are better than numerical simulations. Moreover, the prediction results for unstable VSP state with period‐9 indicate that the optimization of training sets and the number of training iterations are particularly important for the predictability. Besides, the scheme of coded information storage based on the TP‐Bi_LSTM RNN, instead of actual pulse signals, is realized too. The findings offer new applications of deep learning to ultrafast optics and information storage. [ABSTRACT FROM AUTHOR]

Layered van der Waals (vdW) dichalcogenides are distinguished by their unique crystal structures and high structural tunability, rendering them suitable for applications in optics and optoelectronics. Despite significant processes, some fundamental questions remain in two-dimensional (2D) vdW dichalcogenides, such as clarifying detailed structure–property relationship and further improving the optoelectronic performance. Herein, by applying pressure to tune the crystal structure in 2D vdW dichalcogenide SiTe2, we realized a five orders of magnitude boost in photocurrent at 8 GPa. Such an enhancement is attributed to bandgap narrowing and an increased carrier concentration. Furthermore, bandgap closing and metallization were observed at 15.4 GPa, further suggesting the significant change of electronic structure upon compression. This study not only elucidates the intriguing pressure-induced behavior of SiTe2 but also paves the way for harnessing the unique pressure-responsive properties of 2D vdW dichalcogenides in advanced optoelectronic systems. [ABSTRACT FROM AUTHOR]

Deep optical optimization has recently emerged as a new paradigm for designing computational imaging systems using only the output image as the objective. However, it has been limited to either simple optical systems consisting of a single element such as a diffractive optical element or metalens, or the fine-tuning of compound lenses from good initial designs. Here we present a DeepLens design method based on curriculum learning, which is able to learn optical designs of compound lenses ab initio from randomly initialized surfaces without human intervention, therefore overcoming the need for a good initial design. We demonstrate the effectiveness of our approach by fully automatically designing both classical imaging lenses and a large field-of-view extended depth-of-field computational lens in a cellphone-style form factor, with highly aspheric surfaces and a short back focal length. The authors present a design method based on curriculum learning, able to learn optical designs of compound lenses from randomly initialized surfaces without human intervention, demonstrating fully automated design of both classical imaging lenses and extended depth-of-field computational lenses. [ABSTRACT FROM AUTHOR]

Layered van der Waals (vdW) dichalcogenides are distinguished by their unique crystal structures and high structural tunability, rendering them suitable for applications in optics and optoelectronics. Despite significant processes, some fundamental questions remain in two-dimensional (2D) vdW dichalcogenides, such as clarifying detailed structure–property relationship and further improving the optoelectronic performance. Herein, by applying pressure to tune the crystal structure in 2D vdW dichalcogenide SiTe2, we realized a five orders of magnitude boost in photocurrent at 8 GPa. Such an enhancement is attributed to bandgap narrowing and an increased carrier concentration. Furthermore, bandgap closing and metallization were observed at 15.4 GPa, further suggesting the significant change of electronic structure upon compression. This study not only elucidates the intriguing pressure-induced behavior of SiTe2 but also paves the way for harnessing the unique pressure-responsive properties of 2D vdW dichalcogenides in advanced optoelectronic systems. [ABSTRACT FROM AUTHOR]