Hasil untuk "Applied optics. Photonics"

Daria A. Smirnova, D. Leykam, Y. Chong et al.

Rapidly growing demands for fast information processing have launched a race for creating compact and highly efficient optical devices that can reliably transmit signals without losses. Recently discovered topological phases of light provide novel opportunities for photonic devices robust against scattering losses and disorder. Combining these topological photonic structures with nonlinear effects will unlock advanced functionalities such as magnet-free nonreciprocity and active tunability. Here, we introduce the emerging field of nonlinear topological photonics and highlight the recent developments in bridging the physics of topological phases with nonlinear optics. This includes the design of novel photonic platforms which combine topological phases of light with appreciable nonlinear response, self-interaction effects leading to edge solitons in topological photonic lattices, frequency conversion, active photonic structures exhibiting lasing from topologically protected modes, and many-body quantum topological phases of light. We also chart future research directions discussing device applications such as mode stabilization in lasers, parametric amplifiers protected against feedback, and ultrafast optical switches employing topological waveguides.

Renjing Chen, Wenhai Liang, Yilin Xu et al.

Spatial intensity modulation in amplified laser beams, particularly hot spots, critically constrains attainable pulse peak power due to the damage threshold limitations of four-grating compressors. This study demonstrates that the double-smoothing grating compressor (DSGC) configuration effectively suppresses modulation through directional beam smoothing. Our systematic investigation validated the double-smoothing effect through numerical simulations and experimental measurements, with comprehensive spatiotemporal analysis revealing excellent agreement between numerical and practical pulse characteristics. Crucially, the DSGC enables a 1.74 times energy output boost compared to conventional compressors. These findings establish the DSGC as a pivotal advancement for next-generation ultrahigh-power laser systems, providing a viable pathway toward hundreds of PW output through optimized spatial energy redistribution.

S. K. Malick, V. Chavan, V. Chavan et al.

Geospatial technologies are rapidly emerging as pivotal tools for advancing sustainable urban and rural development through citizen empowerment in India and worldwide. This study systematically reviews peer-reviewed and grey literature to examine their integration with global frameworks, such as the SDGs, Paris Agreement, and Sendai Framework, while aligning with Indian initiatives like NAPCC, Smart Cities, Digital India, SVAMITVA, AMRUT, and the National Geospatial Policy 2022, with emphasis on the citizen as a crucial feedback factor. Employing thematic mapping and comparative analysis between the Global North and South, we evaluate applications in urban planning, mobility, energy, resilience, and health, highlighting platforms like PPGIS, VGI, Bhuvan, and 'Know Your DIGIPIN' for participatory data collection and decision-making.</p> <p>Our analysis reveals regional disparities in India, with the southern zone leading in innovation (35% adoption) and the eastern region focussing on disaster management (15%), along with global successes in disaster relief, welfare targeting, and immunisation tracking. Quantitative impacts include India's geospatial market growth to ₹63,000 crores by 2025 and AMRUT 2.0's rapid water and sewerage coverage expansion in many major cities. However, persistent challenges include technical knowledge gaps in academia, insufficient institutional support for geospatial startups, and barriers like low digital literacy and language limitations that restrict broader participation.</p> <p>We recommend enhanced geospatial education, open data policies, vernacular interfaces, and inclusive citizen science frameworks to bridge these gaps, foster equitable participation, and realise geospatial intelligence's full potential for resilient, data-driven sustainability.

E. Letko

This study explores an integrated tunable filter based on lossy mode resonance (LMR) in TiOx thin films, modeled in COMSOL Multiphysics using the Wave Optics and Semiconductor modules. By exploiting the electro-optic (EO) modulation of free carrier concentration in TiOx, the LMR wavelength can be actively tuned under an applied electric field. The results demonstrate a tuning efficiency of 4.0 nm/V, which surpasses many reported EO tunable filters. Optimization studies reveal that thinner ITO electrodes and TiOx layers enhance tuning efficiency, while the initial bulk free carrier concentration has limited influence due to the compensating effect of the Debye length. These findings extend the applicability of LMR beyond sensing, highlighting its potential for active photonic components in integrated optics.

Liuxin Gu, You Zhou

Nonlinear optics has long been a cornerstone of modern photonics, enabling a wide array of technologies, from frequency conversion to the generation of ultrafast light pulses. Recent breakthroughs in two-dimensional (2D) materials have opened a frontier in this field, offering new opportunities for both classical and quantum nonlinear optics. These atomically thin materials exhibit strong light–matter interactions and large nonlinear responses, thanks to their tunable lattice symmetries, strong resonance effects, and highly engineerable band structures. In this paper, we explore the potential that 2D materials bring to nonlinear optics, covering topics from classical nonlinear optics to nonlinearities at the few-photon level. We delve into how these materials enable possibilities, such as symmetry control, phase matching, and integration into photonic circuits. The fusion of 2D materials with nonlinear optics provides insights into the fundamental behaviors of elementary excitations—such as electrons, excitons, and photons—in low-dimensional systems and has the potential to transform the landscape of next-generation photonic and quantum technologies.

Chunyu Huang, Yu Luo, Yule Zhao et al.

Integrated nonlinear optical devices play an important role in modern optical communications; however, conventional on-chip optical devices with homogeneous or periodic translation dimensions generally have limited bandwidth when applied to nonlinear optical applications. So far there lacks a general method to design compact nonlinear optical devices capable of operating over a broadband continuous frequency range. In this work we propose a general strategy based on transformation optics to design curved accelerating waveguides with spatially gradient curvatures, which can achieve broadband nonlinear frequency conversion on chip. Through rigorous analytical calculation, we show that increasing the acceleration (that is, the gradient in the waveguide curvature) broadens the output signal spectrum in the nonlinear process. In this experiment we use sum-frequency generation for infrared signal upconversion as an example and fabricated a variety of curved accelerating waveguides using thin-film lithium niobate on insulators. Efficient sum-frequency generation is observed over a broadband continuous spectrum. Our conformal mapping approach offers a platform for various nonlinear optical processes and works in any frequency range, including visible, infrared and terahertz bands. Apart from lithium niobate on insulators, our approach is also compatible with other nonlinear materials such as silicon, silicon nitride and chalcogenide glasses and so on. Conformal transformation optics is exploited to design curved accelerating waveguides with spatially gradient curvatures to boost the nonlinear efficiency and broaden the bandwidth of the nonlinear optical processes in the waveguides.

M. A. Butt, Xavier Mateos

Integrated photonics is a cutting-edge field that merges optics and electronics on a single microchip, revolutionizing how we manipulate and transmit light. Imagine traditional bulky optical systems condensed onto a chip smaller than a fingernail, enabling faster communication, more efficient sensors, and advanced computing. At its core, integrated photonics relies on guiding light through waveguides etched onto semiconductor substrates, analogous to how wires conduct electricity in traditional electric circuits. These waveguides can route, modulate, and detect light signals with unprecedented precision and speed. This technology holds immense promise across various domains. Despite its immense potential, integrated photonics faces challenges, including manufacturing complexities and integration with existing electronic systems. However, ongoing research and advancements continue to push the boundaries, promising a future where light-based technologies seamlessly integrate into our everyday lives, powering a new era of innovation and connectivity.

K. Gravesen, Asger Brimnes Gardner, E. Ulsig et al.

The foundations of nonlinear optics are revisited, and the formalism is applied to waveguide modes. The effect of loss and dispersion are included rigorously along with the vectorial nature of the modes, and a new version of the nonlinear Schr¨odinger (NLS) equation is derived. This leads to more general expressions for the group index, for the group-index dispersion (GVD), and for the Kerr coefficient. These quantities are essential for the design of waveguides suitable for e.g. the generation of optical frequency combs and all-optical switches. Examples are given using the silicon nitride material platform. Specifically, values are extracted for the coefficients of the chi-3 tensor based on measurements of Kerr coefficients and mode simulations.

A. Kulinich, A. A. Ishchenko

Merocyanines, thanks to their easily adjustable electronic structure, appear to be the most versatile and promising functional dyes. Their D–π–A framework offers ample opportunities for custom design through variations in both donor/acceptor end‐groups and the π‐conjugated polymethine chain, and leads to a broad range of practical properties, including noticeable solvatochromism, high polarizability/hyperpolarizabilities, and the ability to sensitize various physicochemical processes. Accordingly, merocyanines are applied and extensively studied in various fields, such as light‐converting materials for optoelectronics, nonlinear optics, optical storage, solar cells, fluorescent probes, and antitumor agents in photodynamic therapy. This review encompasses both classical and novel more important publications on the structure–property relationships in merocyanines, with particular emphasis on the results by A.  I. Kiprianov and his followers in Institute of Organic Chemistry in Kyiv, Ukraine.

Zhihan Hong, T. Luo, Shibin Jiang et al.

In recent years, 3D printing glass optics has gained massive attention in industry and academia since glass could be an ideal material to make optical elements, including the lens. However, the limitation of materials and printing methods has prevented 3D printing glass optics progress. Therefore, we have developed a novel printing strategy for germanate glass printing instead of pure silica. Moreover, compared with traditional multi-component quartz glass, germanate glass has unmatched advantages for its mid-infrared (MIR) transparency and outstanding visible light imaging performance. Furthermore, compared with non-oxide glass (fluoride glass and chalcogenide glass), germanate glass has much better mechanical, physical, and chemical properties and a high refractive index. Germanate glass has been widely applied in remote sensing, ranging, environmental detection, and biomedical detection. However, it is difficult to shape, cast, polish, and grind for optical and photonics applications such as imaging optics and laser-collimation optics. These drawbacks have made germanate glass inaccessible to complex optical elements and greatly increased their cost. In this report, we use germanate glass fibers with a diameter of 125 µm based on fiber-fed laser heating technology to fabricate an mm-size optical application. In this paper, we combine the fiber-fed laser heating technology with an optimized temperature control process to manufacture high-precision optical elements. Germanate glass optics can be printed with excellent visible light and IR transparency and a smooth surface with roughness under 4 nm. By optimizing the layer-by-layer 3D printing process and the thermal feedback in the printing process, we avoid cracks and minimize surface deformation. This work shows the possibility of the mm-size glass optical elements 3D printing and widens its application for IR optics.

Júlia Ferrer Ortas, Pierre Mahou, Sophie Escot et al.

Color TSFG microscopy is a novel approach for label-free imaging of red blood cells and oxygenation in situ.

Alla G. Polyakova, Anna G. Soloveva, Petr V. Peretyagin et al.

The development of anti-pain technologies in the complex treatment of pain syndromes is one of the most urgent tasks of modern medicine. We undertook a placebo-controlled experimental study of the therapeutic potential of low-intensity laser radiation when applied to acupuncture points that are directly related to the autonomic nervous system. The adaptation effect of puncture photobiomodulation on the induction of stress-mediated autonomic reactions, oxidative metabolism and microcirculation in animals during the acute phase of pain stress was revealed. The data obtained are of interest for use in the complex rehabilitation of patients with pain syndromes.

S. Nietiedt, T. Luhmann

The verification of a measurement system is an essential part of system development. For this purpose, various guidelines can be used to evaluate and validate photogrammetric systems. However, these guidelines are only designed to validate systems that observe a static scene. Hence, these guidelines cannot validate measurement systems that observe dynamic scenes. In addition, reference data is not available for most systems, making verification significantly more difficult or not a practical solution. In this work, a simulation-based verification approach is presented. The presented approach allows the analysis of complex systems and the investigation of specific processing steps. The approach is based on a Monte Carlo simulation, which only requires the probability density distributions of the input data and synthetic reference data. For this purpose, the probability density distributions of the input data are determined by kernel density estimation to generate realistic input data. The application is a wind tunnel test, where aerodynamic and structural dynamic phenomena are observed at a wind turbine model. The measurement system consists of four high-speed cameras, which acquire the rotor blades' deformations. The objective of the simulation is to evaluate the complete process regarding the accuracy and precision of the measurement system. Experimental data can be used to estimate the quality of the simulation. It was shown that the simulation produces realistic results and that it is suitable for validating dynamic measurement systems. The simulation showed that the precision and accuracy of the system are highly dependent from the estimation of the self-motion. The achieved accuracy is still high and allows the detection of small-scale blade deformations.

Alfredo Borgia, Raffaele Raimondi, Tania Sorrentino et al.

The purpose of this study was to summarize the results related to ocular biometry performed using swept-source optical coherence tomography (SS-OCT). A literature search was conducted to search articles reporting the clinical outcomes of patients who underwent examinations with commercially available SS-OCT machines. The available data were thoroughly analyzed, with a particular focus on all the biometric factors used to calculate the power of intraocular lenses (IOLs) implanted during cataract surgery. The agreement, repeatability, and reproducibility of several parameters among different devices were examined. The variations found for parameters obtained from agreement testing were evaluated in order to promote the interchangeability of devices. Swept-source optical coherence tomography biometers usually produce highly repeatable and reproducible results. The excellent results obtained led us to the conclusion that optical biometers based on SS-OCT technology will probably take the lead in ocular biometry.

Da Xu, X. Xiong, Lin Wu et al.

Surface plasmons allow electromagnetic fields to be confined to subwavelength scale, well beyond the classical optical diffraction limit. With continuous reduction of optical mode volume into the deep subwavelength scale, a new era of quantum plasmonics opens up that investigates the quantum behavior of surface plasmons and their interactions with matter. This emerging and exciting field creates many new opportunities in advancing the boundaries of fundamental science and applied quantum technology. This review covers recent breakthroughs from three unique and important perspectives: the fundamental quantum properties of plasmon-polaritons, plasmon-polaritons interacting with quantum emitters, and plasmon-polaritons stepping into quantum technology. A clear development map of quantum plasmonics is also established for the reader.

Christophe Heinkelé, Pierre Charbonnier, Philippe Foucher et al.

Le présent article décrit l'implémentation d'une méthode de pré-location décimétrique d'images au sein de grands volumes de données dans des tunnels navigables et routiers. Elle repose sur une technique d'odométrie visuelle simplifiée, ce qui la rend rapide et facile à mettre en oeuvre. Cette méthode permet de structurer les données afin d'améliorer les traitements postérieurs, comme par exemple la reconstruction 3D par photogrammétrie. La méthode est évaluée sur la précision de la localisation par comparaison avec des techniques de localisation plus conventionnelles. La structuration des données qui découle de cette localisation des images au sein de l'ouvrage constitue l'aspect le plus important du travail présenté ici.

Giuseppe M. Paternò, Giovanni Manfredi, Francesco Scotognella et al.

Real-time monitoring of bacterial contaminants and pollutants in food is of paramount importance nowadays, owing to the impressive extension of the food production/supply chain and the consequent increase in foodborne outbreaks worldwide. This represents a serious risk for consumers’ health and accounts for a large fraction of food wastage, especially in the developed countries. Therefore, modern sensors for food quality control should possibly afford low-cost, portability, and easiness of readout to enable widespread diffusion of the technology, thus allowing food quality monitoring from the production/supply chain to the consumers’ table. In these regards, one-dimensional photonic crystals, also known as Distributed Bragg Reflectors (DBRs), can represent simple yet efficient all-optical and label-free colorimetric sensors, given their relatively high color purity, easiness of integration with a large number of stimulus responsive materials, and low-cost fabrication from scalable processes. In this perspective article, we discuss the development of DBRs-based colorimetric sensors for the monitoring of bacterial contaminants and pollutants of interest in the food quality sector. We aim at providing a systematic overview on the main approaches that have been employed to achieve selectivity and sensitivity in DBRs-based sensors, with the view to enable widespread use of this technology at both the industry/supply chain and customers’ level.

J. R. Santillan, J. R. Santillan, A. M. Amora et al.

Changes in land cover can have negative impacts on the hydrological and hydraulic processes in river basins and watersheds such as increase in surface runoff and peak flows, and greater incidence, risk and vulnerability of flooding. In this study, the impacts of land-cover changes to the hydrologic and hydraulic behaviours of the Agusan River Basin (ARB), the third largest river basin in the Philippines, was analysed using an integrated approach involving Remote Sensing (RS), Geographic Information System (GIS), and hydrologic and hydraulic models. Different land-cover classes in the ARB for the years 1995 and 2017 were mapped using Landsat 5 TM and Landsat 8 OLI images. Using a post-classification change detection approach, changes in land-cover were then determined. The impacts of these changes in land-cover to the to the basin discharge were then estimated using a calibrated hydrologic model based on the Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS) under different extreme rainfall conditions. The impact of the changes in land-cover to flood depth and extent was also determined using a hydraulic model based on the HEC-RAS (River Analysis System). Land cover classification results revealed that the ARB is 67.7% forest in 1995 but have decreased to 62.8% in 2017. Agricultural areas in the basin were also found to have increased from 12.2% to 15.5% in the same period. Other notable land cover changes detected include the increase in built-up lands and range lands, and decrease in barren lands. HEC HMS and HEC RAS model simulation results showed that there was an increase in discharge, flood depth, and flood extents between 1995 and 2017, implying that that the detected changes in land cover have negative impacts to hydrologic and hydraulic behaviours of the ARB.

Andréa Deschênes, Flavie Lavoie-Cardinal, M. Méthot et al.

In 2008, Universite Laval launched the first and only graduate programs in biophotonics in Canada. This initiative is dedicated to the training of a new generation of highly qualified researchers at the interface of life sciences and optics. It also stemmed from the strong expertise of the University in optics/photonics, its major investments in state-of-the art biophotonics infrastructure and technologies, and its desire to promote multidisciplinary training of graduate students. The programs are hosted by the Faculty of Science and Engineering in collaboration with the Faculty of Medicine, regrouping professors from 3 Faculties and 10 departments at Universite Laval. The biophotonics graduate programs offer students from a wide variety of scientific backgrounds the opportunity to train in highly skilled research teams on projects that bridge the gap between traditional research fields. They benefit from transdisciplinary training opportunities in the fields of physics, chemistry, biology, biochemistry, neurosciences, medicine, engineering and ethics.

A. Maiti, P. Acharya

The Indo-Gangetic basin is one of the productive rice growing areas in South-East Asia. Within this extensive flat fertile land, lower Gangetic basin, especially the south Bengal, is most intensively cultivated. In this study we map the rice growing areas using Moderate Resolution Imaging Spectroradiometer (MODIS) derived 8-day surface reflectance product from 2014 to 2015. The time series vegetation and wetness indices such as Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI) and Land Surface Water Index (LSWI) were used in the decision tree (DT) approach to detect the rice fields. The extracted rice pixels were compared with Landsat OLI derived rice pixels. The accuracy of the derived rice fields were computed with 163 field locations, and further compared with statistics derived from Directorate of Economics and Statistics (DES). The results of the estimation shows a high degree of correlation (<i>r</i>&thinsp;=&thinsp;0.9) with DES reported area statistics. The estimated error of the area statistics while compared with the Landsat OLI was &plusmn;15%. The method, however, shows its efficiency in tracing the periodic changes in rice cropping area in this part of Gangetic basin and its neighboring areas.