Hasil untuk "Applied optics. Photonics"

P. Kok, W. Munro, K. Nemoto et al.

Linear optics with photon counting is a prominent candidate for practical quantum computing. The protocol by Knill, Laflamme, and Milburn [2001, Nature (London) 409, 46] explicitly demonstrates that efficient scalable quantum computing with single photons, linear optical elements, and projective measurements is possible. Subsequently, several improvements on this protocol have started to bridge the gap between theoretical scalability and practical implementation. The original theory and its improvements are reviewed, and a few examples of experimental two-qubit gates are given. The use of realistic components, the errors they induce in the computation, and how these errors can be corrected is discussed.

S. Coskun, C. Bayik, S. Abdikan et al.

Earthquakes are among the most devastating natural events. Interferometric Synthetic Aperture Radar (InSAR) methods are used to obtain fault parameters from co-seismic earthquakes, particularly those covering large areas. This study presents initial analyses to see the effects of the 2023 Kahramanmaraş earthquake that occurred along the East Anatolian Fault Zone of Türkiye. The study area covers the Hatay region. The analysis of different structures and earthquake-triggered landslides was conducted to investigate their impact. The small baseline method was applied to Sentinel-1 data taken in both the ascending and descending directions. The images cover the years 2019 and 2024, including the earthquake. The results vary between -20 cm/year and 25 cm/year. The earthquake co-seismic effect is visible in the time series obtained in both directions, and structural movement was observed leading up to and following the earthquake. This allows structures caused by an earthquake to be monitored afterward. Furthermore, events such as landslides and landslides that may be triggered by an earthquake can be monitored.

J. Lee, J. Park, Y. Park et al.

With the expansion of digital heritage practices, the concept of &ldquo;restoration&rdquo; has increasingly been applied in digital contexts. However, this trend has blurred the boundaries between restoration, reconstruction, simulation, and imaginative projection, weakening the philosophical legitimacy of restoration itself. This study revisits the proper criteria for applying the concept of restoration in digital environments, focusing on Cesare Brandi&rsquo;s restoration theory, particularly the notion of <em>unit&agrave; potenziale</em> (potential unity). It argues that even without physical intervention, digital restoration must meet the ethical and philosophical standards inherent to restoration. To examine practical applications, the study analyses the Kaesong Manwoldae Digital Restoration Platform, which was designed to distinguish between conservation and reconstruction, thereby ensuring authenticity is clearly conveyed to users. This research asserts that the concept of restoration must continue to be grounded in ethical and philosophical principles in the digital age and proposes concrete strategies for implementing this standard.

Haolin Yang, Ruili Zhang, Sailing He

1.6 µm ultrafast lasers are important in biomedical applications because the wavelength is located within an attractive biological window called the near-infrared-II (NIR-II) region. However, for erbium- or thulium-doped fibers, 1.6 μm is not their typical gain wavelength; therefore, realizing a high power femtosecond (fs) 1.6 μm laser is a challenging task. In this work, we propose a pump scheme assisted by a C-band laser. The new pump scheme can improve the gain at 1.6 μm with a mechanism originating from the re-absorption effect of the ground state and the in-band relaxation between the splitting energy levels 4I13/2b and 4I13/2a. Applying the pump scheme to the all-fiber large-mode-area (LMA) chirped pulse amplification (CPA) system, we achieve a record-high output power of ∼9.42 W, corresponding to a 262 nJ single pulse energy. The pulse duration after compression is ∼361 fs. Our approach of combining a LMA CPA system with a C-band auxiliary laser co-pumping scheme opens a way to increase the output power of an erbium-doped fiber laser by one order of magnitude in the 1600 nm region, even though this is a low gain region.

F. Chiabrando, F. Gallitto, M. Grella et al.

The increasing globalisation of trade and climate change are accelerating the spread of invasive pest species, posing significant threats to agriculture. The Japanese beetle (Popillia japonica Newman), first recorded in northern Italy in 2014, is a highly destructive pest with severe economic impacts, particularly in viticulture. Effective monitoring is essential for timely intervention, yet conventional field-based surveys are resource-intensive and limited in spatial coverage.<br />This study presents a novel UAV-based monitoring framework integrating near-infrared (NIR) imaging and machine learning algorithms to detect Popillia japonica adults in vineyard environments. Field experiments were conducted in two commercial vineyards in northern Italy during the beetle's summer flight season. A standardised and replicable aerial data acquisition protocol was developed using lightweight multispectral sensors mounted on rotary-wing UAV platforms. Detected insect signatures were processed through a custom CV pipeline and validated through entomological ground truthing via manual counts.<br />Results show a strong correlation between CV-derived detections and manual observations, with Pearson correlation coefficients ranging from 0.89 to 0.96. Although the system tends to overestimate insect counts under certain canopy conditions slightly, its integration into a GIS environment enabled the near real-time generation of prescription maps. These maps were used to guide site-specific drone spraying treatments, applying insecticides only in hotspot areas where infestation thresholds were exceeded.<br />This UAV-enabled, semi-automated monitoring approach significantly reduces survey time and human exposure to agrochemicals, while supporting precision pest management at scale. The methodology offers a promising framework for integrating remote sensing, AI, and entomological validation, with broader applications for managing invasive species in precision agriculture contexts.

Junwoo Park, Nataliya Sokolovska, Clément Cabriel et al.

In recent years, the segmentation of short molecular trajectories with varying diffusive properties has drawn particular attention of researchers, since it allows studying the dynamics of a particle. In the past decade, machine learning methods have shown highly promising results, also in changepoint detection and segmentation tasks. Here, we introduce a novel iterative method to identify the changepoints in a molecular trajectory, i.e. frames, where the diffusive behavior of a particle changes. A trajectory in our case follows a fractional Brownian motion and we estimate the diffusive properties of the trajectories. The proposed Bottom-up iterative anomalous diffusion detector (BI-ADD) combines unsupervised and supervised learning methods to detect the changepoints. Our approach can be used for the analysis of molecular trajectories at the individual level and also be extended to multiple particle tracking, which is an important challenge in fundamental biology. We validated BI-ADD in various scenarios within the framework of the 2nd anomalous diffusion challenge 2024 dedicated to single particle tracking. Our method is implemented in Python and is publicly available for research purposes.

Nan Zheng, Ričardas Buividas, Hsin-Hui Huang et al.

Laser machining by ultra-short (sub-ps) pulses at high intensity offers high precision, high throughput in terms of area or volume per unit time, and flexibility to adapt processing protocols to different materials on the same workpiece. Here, we consider the challenge of optimization for high throughput: how to use the maximum available laser power and larger focal spots for larger ablation volumes by implementing a fast scan. This implies the use of high-intensity pulses approaching ∼PW/cm² at the threshold where tunneling ionization starts to contribute to overall ionization. A custom laser micromachining setup was developed and built to enable high speed, large-area processing, and easy system reconfiguration for different tasks. The main components include the laser, stages, scanners, control system, and software. Machining of metals such as Cu, Al, or stainless steel and fused silica surfaces at high fluence and high exposure doses at high scan speeds up to 3 m/s were tested for the fluence scaling of ablation volume, which was found to be linear. The largest material removal rate was 10 mm³/min for Cu and 20 mm³/min for Al at the maximum power 80 W (25 J/cm² per pulse). Modified surfaces are color-classified for their appearance, which is dependent on surface roughness and chemical modification. Such color-coding can be used as a feedback parameter for industrial process control.

Volatier Jean-Baptiste, Beaussier Stephane J., Druart Guillaume et al.

In this article we describe the implementation of Freeform Optics Raytracer with Manufacturable Imaging Design cApaBiLitiEs (FORMIDABLE): an optical design library capable of simulating optical systems by ray-tracing. Optical performance can be quantified and optimised using third-party optimisation algorithms. Compared to available commercial optical design software and similarly to fast accurate NURBS optimization (FANO), our code can simulate and optimise Non-uniform rational B-Spline (NURBS). It also implements generalized differential capabilities that allows faster convergence compared to state-of-the-art. The implementation of FORMIDABLE and its innovative capabilities are described and illustrated with a representative case-study. The source code is available to eligible third-parties under the ECSL licence.

Xiang Li, Xiaoli Shi, Xiaolong Zhang et al.

Eyal Rozenberg, Aviv Karnieli, O. Yesharim et al.

We propose a novel, physically-constrained and differentiable approach for the generation of D-dimensional qudit states via spontaneous parametric down-conversion (SPDC) in quantum optics. We circumvent any limitations imposed by the inherently stochastic nature of the physical process and incorporate a set of stochastic dynamical equations governing its evolution under the SPDC Hamiltonian. We demonstrate the effectiveness of our model through the design of structured nonlinear photonic crystals (NLPCs) and shaped pump beams; and show, theoretically and experimentally, how to generate maximally entangled states in the spatial degree of freedom. The learning of NLPC structures offers a promising new avenue for shaping and controlling arbitrary quantum states and enables all-optical coherent control of the generated states. We believe that this approach can readily be extended from bulky crystals to thin Metasurfaces and potentially applied to other quantum systems sharing a similar Hamiltonian structures, such as superfluids and superconductors.

Nicolas Roy, L. König, O. Absil et al.

Metasurfaces offer a flexible framework for the manipulation of light properties in the realm of thin film optics. Specifically, the polarization of light can be effectively controlled through the use of thin phase plates. This study aims to introduce a surrogate optimization framework for these devices. The framework is applied to develop two kinds of vortex phase masks (VPMs) tailored for application in astronomical high-contrast imaging. Computational intelligence techniques are exploited to optimize the geometric features of these devices. The large design space and computational limitations necessitate the use of surrogate models like partial least squares Kriging, radial basis functions, or neural networks. However, we demonstrate the inadequacy of these methods in modeling the performance of VPMs. To address the shortcomings of these methods, a data-efficient evolutionary optimization setup using a deep neural network as a highly accurate and efficient surrogate model is proposed. The optimization process in this study employs a robust particle swarm evolutionary optimization scheme, which operates on explicit geometric parameters of the photonic device. Through this approach, optimal designs are developed for two design candidates. In the most complex case, evolutionary optimization enables optimization of the design that would otherwise be impractical (requiring too much simulations). In both cases, the surrogate model improves the reliability and efficiency of the procedure, effectively reducing the required number of simulations by up to 75% compared to conventional optimization techniques.

W. X. Wang, G. X. Zhong, J. J. Huang et al.

Buildings are an important part of the urban scene. In this paper, a novel instance segmentation framework for 3D mesh models in urban scenes is proposed. Unlike existing works focusing on semantic segmentation of urban scenes, this work focuses on detecting and segmenting 3D building instances even if they are attached and occluded in a large and imprecise 3D surface model. Multi-view images are first enhanced to RGBH images by adding a height map and are segmented to obtain all roof instances using Mask R-CNN. The 2D roof instances are then back-projected onto the 3D scene, the accurate 3D roof instances are obtained using a novel 3D clustering method and two post-processing steps which preserve the largest connected region and remove the model ambiguity. Finally, the 2D convex hull of each 3D roof instance is calculated and the model is divided within the range into building instances. The performance of the proposed methods is evaluated using real UAV images and the corresponding 3D mesh models qualitatively and quantitatively. Results revealed that the proposed method could effectively segment the model of the urban scenes and building instance is obtained, the over-segmentation masks can be clustered correctly into roof instances and the under-segmentation masks caused by image segmentation errors are eliminated.

Vipin Tiwari, Nandan S. Bisht

Jones–Stokes polarimetry is a robust in vitro polarimetric technique that can be used to investigate the anisotropic properties of a birefringent medium. The study of spatially resolved Jones matrix components of an object is a heuristic approach to extract its phase and polarization information. However, direct interpretation of Jones matrix elements and their decomposition into associated anisotropic properties of a sample is still a challenging research problem that needs to be investigated. In this paper, we experimentally demonstrate combined Jones–Stokes polarimetry to investigate the amplitude, phase, and polarization modulation characteristics of a twisted nematic liquid crystal spatial light modulator (TNLC-SLM). The anisotropic response of the SLM is calibrated for its entire grayscale range. We determine the inevitable anisotropic properties viz., diattenuation, retardance, isotropic absorption, birefringence, and dichroism, which are retrieved from the measured Jones matrices of the SLM using Jones polar decomposition and a novel algebraic approach for Jones matrix decomposition. The results of this study provide a complete polarimetric calibration of the SLM within the framework of its anisotropic characteristics.

Peter Schelkens, Ayyoub Ahar, Antonin Gilles et al.

While 60 years of successful application of holography is celebrated in this special issue, efficient representation and compression of holographic data has received relatively little attention in research. Notwithstanding this observation, and particularly due to the digitization that is also penetrating the holographic domain, interest is growing on how to efficiently compress holographic data such that interactive exchange of content, as well as digital storage can be facilitated proficiently. This is a particular challenge, not only because of its interferometric nature and the various representation formats, but also the often extremely large data volumes involved in pathological, tomographic, or high-end visualization applications. In this paper, we provide an overview of the state of the art in compression techniques and corresponding quality metrics for various practical applications in digital holography. We also consider the future by analyzing the emerging trends for addressing the key challenges in this domain.

Le-Yi Zhao, Hai Wang, Hai-Yu Wang et al.

Abstract Strong light-matter interactions in two-dimensional transition metal dichalcogenides (TMDCs) with robust spin-valley degrees of freedom open up the prospect of valleytronic devices. A thorough understanding on the dynamics of the valley polarizations in the strong coupling regime is urgently required. Here, multiple polarized TMDCs-SPPs hybrid systems were constructed by combining monolayer WS2 flakes to linear, circular, and spiral Ag gratings, resulting in linear and circular polarized modulation on the coherent hybrid states, respectively. Particularly, valley polaritons can be tailored asymmetrically by chiral strong coupling regime. Furthermore, the dynamics of the polarized polaritons were directly analyzed by transient absorption (TA) measurement. Both of the linear and circular polarization difference in the TA spectra can be retained for a remarkable long time, leading to a polarized PL even at room temperature. More importantly, in the chiral strong coupled WS2-spiral Ag grating devices, the mechanism of the asymmetrical valley-polarized PL (p σ+ = 14.9% and p σ- = 10.8%) is proved by the opposite valley polarization dynamics in the circularly polarized TA spectra. The multiple polarization modulation in monolayer TMDCs-SPPs strong coupling devices could provide a viable route toward multiple polarization polaritonic devices.

Kosar Jafarizade, Zahra Hosseini, Hossein Amanati Manbar

The relatively large bandgaps of the methylammonium lead halide perovskites are the major obstacle to achieving broadband response in the lead-based perovskite photodetectors. Partial or total substitution of lead with tin leads to smaller bandgaps for perovskite materials. Here, we investigated the application of a mixed tin-lead perovskite material, (FASnI3)0.6(MAPbI3)0.4, with small bandgap of 1.24 eV as the absorber material in a perovskite photodetector. The device simulation is performed by using SCAPS simulation software. The effect of different parameters such as absorber layer quality and thickness, interface defects, doping concentration and carrier mobility on the performance of the device is studied. The simulation results clarify that the parameters optimization can result in achieving a self-powered photodetector with broad spectral response from 300 to 1050 nm wavelength, a high responsivity of 0.6 A W-1 at 930 nm, almost flat detectivity of over 1013 Jones and a wide linear dynamic range. We believe this study can provide theoretical guidance for the design of highly sensitive, broadband, mixed tin-lead perovskite photodetectors.

Xiaona Ye, Shijie Liu, Yuping Chen et al.

Whispering-gallery-mode microresonators, one of the most important components of photonic integrated circuits, have the ability to dramatically boost light–matter interactions. In this Letter, we demonstrate effective sum-frequency generation via modal phase matching in a triply resonant lithium-niobate-on-insulator microdisk resonator through two individual continuous wave pumps working in the communication band. The sum-frequency conversion efficiency is measured to be ${2.22} \times {{10}^{ - 6}}\;\,\,{{\rm mW}^{ - 1}}$2.22×10−6mW−1. This work shows a high-efficiency frequency convertor that may be applied in on-chip integrated optics in the future.

J. Dudley, J. Taylor

G. An, X. Hao, Shuguang Li et al.

P. Knoefel, D. Herrmann, M. Sindram et al.

The research and development project named Landscape Change Detection Service (German abbreviation: LaVerDi) was initiated by the German Federal Agency for Cartography and Geodesy (BKG). Within the scope of the project a monitoring service for landscape changes was developed and implemented using free Copernicus satellite data for an automated derivation of potential land cover change. This change indication is meant to be used to update or continue BKG in-house products, such as the Digital Land Cover Model Germany (LBM-DE), in a comprehensive and uniform quality. The results can be further used for numerous applications or as change information for administration and planning, and for the compilation of spatial statistics. It satisfies the users' need for a national service for open data on land cover changes and thus represents the first automatic and verified national satellite product for land cover changes in Germany. As input data the service uses pre-processed Sentinel-2 data from the European Copernicus satellite program, as well as an image segmentation approach to extract change objects. Using an improved cloud mask algorithm, Sentinel-2 tiles with up to maximum cloud coverage of 60% can be used for analysis. The service (data processing, change detection, visualisation) runs on the German “Copernicus Data and Utilization Platform” (CODE-DE). As of December 2020, the INSPIRE-compliant LaVerDi web service is operational. The thematic accuracy of the generated change layers is above the given requirements (minimum of 80%), considering the 95% confidence interval for all relevant land cover classes in certain test areas. The transferability of the methodology has been successfully shown by a prototypic nationwide demonstrator in early 2020 and is therefore expected to reliably detect both long-term and seasonal changes.