Hasil untuk "Optics. Light"

K. Bliokh, F. J. Rodríguez-Fortuño, F. Nori et al.

This Review article provides an overview of the fundamental origins and important applications of the main spin–orbit interaction phenomena in modern optics that play a crucial role at subwavelength scales. Light carries both spin and orbital angular momentum. These dynamical properties are determined by the polarization and spatial degrees of freedom of light. Nano-optics, photonics and plasmonics tend to explore subwavelength scales and additional degrees of freedom of structured — that is, spatially inhomogeneous — optical fields. In such fields, spin and orbital properties become strongly coupled with each other. In this Review we cover the fundamental origins and important applications of the main spin–orbit interaction phenomena in optics. These include: spin-Hall effects in inhomogeneous media and at optical interfaces, spin-dependent effects in nonparaxial (focused or scattered) fields, spin-controlled shaping of light using anisotropic structured interfaces (metasurfaces) and robust spin-directional coupling via evanescent near fields. We show that spin–orbit interactions are inherent in all basic optical processes, and that they play a crucial role in modern optics.

A. Zayats, I. Smolyaninov, A. Maradudin

S. Yun, Sheldon J. J. Kwok

Light and optical techniques have made profound impacts on modern medicine, with numerous lasers and optical devices currently being used in clinical practice to assess health and treat disease. Recent advances in biomedical optics have enabled increasingly sophisticated technologies — in particular, those that integrate photonics with nanotechnology, biomaterials and genetic engineering. In this Review, we revisit the fundamentals of light–matter interactions, describe the applications of light in imaging, diagnosis, therapy and surgery, overview their clinical use, and discuss the promise of emerging light-based technologies. This Review provides a broad account of the applications of light in imaging, diagnosis, therapy and surgery, and discusses the promise of emerging light-based technologies.

J. Dudley, G. Genty, A. Mussot et al.

Over a decade ago, an analogy was drawn between the generation of large ocean waves and the propagation of light fields in optical fibres. This analogy drove numerous experimental studies in both systems, which we review here. In optics, we focus on results arising from the use of real-time measurement techniques, whereas in oceanography we consider insights obtained from analysis of real-world ocean wave data and controlled experiments in wave tanks. This Review of the work in hydrodynamics includes results that support both nonlinear and linear interpretations of rogue wave formation in the ocean, and in optics, we also provide an overview of the emerging area of research applying the measurement techniques developed for the study of rogue waves to dissipative soliton systems. We discuss the insights gained from the analogy between the two systems and its limitations in modelling real-world ocean wave scenarios that include physical effects that go beyond a one-dimensional propagation model.An analogy between wave propagation in hydrodynamics and in optics has yielded new insights into the mechanisms leading to the formation of giant rogue waves on the ocean. We review experimental progress and field measurements in this area.Key pointsAn analogy between wave propagation on the ocean and in optical fibres has provided new insights into the physical mechanisms and dynamical features that underpin the occurrence of rogue waves.Real-time measurement techniques studying instabilities in fibre optics have highlighted the emergence of localized breather structures associated with nonlinear focusing, a scenario confirmed in wave-tank experiments.The experimental techniques developed for rogue wave measurement in optics have also yielded improved understanding of transient dynamics and dissipative soliton structures in lasers.Advanced analysis and hindcasting of real-world ocean wave data have revealed the central role of directionality and the superposition of random wave trains in the formation of ocean rogue waves.The emergence of oceanic rogue waves in the general case is likely to arise from both linear and nonlinear mechanisms to different degrees depending on the prevalent wind and sea state conditions.Machine learning could play a key role in future efforts to forecast and predict ocean rogue waves and to identify new areas of physical analogy and overlap between optics and hydrodynamics.

S. Colburn, A. Zhan, A. Majumdar

We design metalenses to capture colored images with white light by combining metasurfaces and computational imaging. Conventional imaging systems comprise large and expensive optical components that successively mitigate aberrations. Metasurface optics offers a route to miniaturize imaging systems by replacing bulky components with flat and compact implementations. The diffractive nature of these devices, however, induces severe chromatic aberrations, and current multiwavelength and narrowband achromatic metasurfaces cannot support full visible spectrum imaging (400 to 700 nm). We combine principles of both computational imaging and metasurface optics to build a system with a single metalens of numerical aperture ~0.45, which generates in-focus images under white light illumination. Our metalens exhibits a spectrally invariant point spread function that enables computational reconstruction of captured images with a single digital filter. This work connects computational imaging and metasurface optics and demonstrates the capabilities of combining these disciplines by simultaneously reducing aberrations and downsizing imaging systems using simpler optics.

Sirimuvva Tadepalli, J. Slocik, Maneesh K. Gupta et al.

M. Broxton, L. Grosenick, Samuel J. Yang et al.

Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method.

Jialiang Xu, Xinyue Li, Jianbo Xiong et al.

Halide perovskites provide an ideal platform for engineering highly promising semiconductor materials for a wide range of applications in optoelectronic devices, such as photovoltaics, light‐emitting diodes, photodetectors, and lasers. More recently, increasing research efforts have been directed toward the nonlinear optical properties of halide perovskites because of their unique chemical and electronic properties, which are of crucial importance for advancing their applications in next‐generation photonic devices. Here, the current state of the art in the field of nonlinear optics (NLO) in halide perovskite materials is reviewed. Halide perovskites are categorized into hybrid organic/inorganic and pure inorganic ones, and their second‐, third‐, and higher‐order NLO properties are summarized. The performance of halide perovskite materials in NLO devices such as upconversion lasers and ultrafast laser modulators is analyzed. Several potential perspectives and research directions of these promising materials for nonlinear optics are presented.

F. Herrera, J. Owrutsky

This is a tutorial-style introduction to the field of molecular polaritons. We describe the basic physical principles and consequences of strong light-matter coupling common to molecular ensembles embedded in UV-visible or infrared cavities. Using a microscopic quantum electrodynamics formulation, we discuss the competition between the collective cooperative dipolar response of a molecular ensemble and local dynamical processes that molecules typically undergo, including chemical reactions. We highlight some of the observable consequences of this competition between local and collective effects in linear transmission spectroscopy, including the formal equivalence between quantum mechanical theory and the classical transfer matrix method, under specific conditions of molecular density and indistinguishability. We also overview recent experimental and theoretical developments on strong and ultrastrong coupling with electronic and vibrational transitions, with a special focus on cavity-modified chemistry and infrared spectroscopy under vibrational strong coupling. We finally suggest several opportunities for further studies that may lead to novel applications in chemical and electromagnetic sensing, energy conversion, optoelectronics, quantum control, and quantum technology.

Cheng Zhang, S. Divitt, Qingbin Fan et al.

Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging, displaying, sensing, spectroscopy, and metrology. Towards this goal, metasurfaces—planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements—have been exploited at frequencies ranging from the microwave range up to the visible range. Here, we demonstrate high-performance metasurface optical components that operate at ultraviolet wavelengths, including wavelengths down to the record-short deep ultraviolet range, and perform representative wavefront shaping functions, namely, high-numerical-aperture lensing, accelerating beam generation, and hologram projection. The constituent nanostructured elements of the metasurfaces are formed of hafnium oxide—a loss-less, high-refractive-index dielectric material deposited using low-temperature atomic layer deposition and patterned using high-aspect-ratio Damascene lithography. This study opens the way towards low-form factor, multifunctional ultraviolet nanophotonic platforms based on flat optical components, enabling diverse applications including lithography, imaging, spectroscopy, and quantum information processing. An array of hafnium oxide nanopillars on a fused silica substrate efficiently manipulates a broad range of ultraviolet light wavelengths, with potential applications in photolithography, imaging, spectroscopy, and quantum information processing. A resist-based Damascene process was developed by a team led by Cheng Zhang, Ting Xu and Henri J. Lezec in China and the USA. They used lithography to design spaces into a resist template that were then filled with hafnium oxide. The resist was removed with solvent to leave high-aspect-ratio hafnium oxide nanopillars. The pillar height, diameter and orientation, as well as the spacing between the pillars, control how UV light propagates through the thin ‘metasurface’. Metasurfaces were used to focus UV light like a lens; transform incident UV light into a propagating, curving output beam; and generate holograms from three UV light wavelengths.

Tatsuki Tahara

I propose a digital holographic microscopy technique in which complex amplitude distributions at multiple wavelengths are simultaneously obtained with a common-path self-reference interferometer and a monochrome image sensor. The computational coherent superposition scheme is applied to reconstruct a multiwavelength holographic image from a small number of wavelength-multiplexed phase-shifted holograms. Optical systems adopting a commercially available optical microscope with a light-emitting diode and a halogen lamp are constructed and their applicabilities to multiwavelength three-dimensional microscopy and quantitative phase microscopy are experimentally demonstrated. The possibility of single-shot measurement with a monochrome image sensor is discussed.

Sergey Kh. Batygov, Liudmila V. Moiseeva, Valeria V. Vinokurova et al.

Ce3+ luminescence was studied in a flurozirconate glass in the ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) and in a fluorohafnate HfF4-BaF2-LaF3-AlF3-NaF (HBLAN) glass systems under X-ray and UV excitation. Ce3+ luminescence temperature quenching in glasses in the temperature range 77–300 K was observed. The Ce3+ luminescence quenching in ZBLAN glass host is conditioned by two mechanisms: via the electrons ionization from the excited 5d-level of Ce3+ into the conduction band (CB); and quenching as a result of the intersection of the Ce3+ ground state and excited state potential curves. In HBLAN glass host the luminescence quenching is caused by the intersection of the Ce3+ ground state and excited state potential curves in the temperature range 77–300 K. The activation energies of Ce3+ luminescence quenching in ZBLAN and HBLAN have been determined.

Cheng Guo, V. Asadchy, Bo Zhao et al.

Weyl semimetals are topological materials whose electron quasiparticles obey the Weyl equation. They possess many unusual properties that may lead to new applications. This is a tutorial review of the optical properties and applications of Weyl semimetals. We review the basic concepts and optical responses of Weyl semimetals, and survey their applications in optics and thermal photonics. We hope this pedagogical text will motivate further research on this emerging topic.

Stephanie C. Malek, A. Overvig, A. Alú et al.

Photonic devices rarely provide both elaborate spatial control and sharp spectral control over an incoming wavefront. In optical metasurfaces, for example, the localized modes of individual meta-units govern the wavefront shape over a broad bandwidth, while nonlocal lattice modes extended over many unit cells support high quality-factor resonances. Here, we experimentally demonstrate nonlocal dielectric metasurfaces in the near-infrared that offer both spatial and spectral control of light, realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies unaffected. Our devices attain this functionality by supporting a quasi-bound state in the continuum encoded with a spatially varying geometric phase. We leverage this capability to experimentally realize a versatile platform for multispectral wavefront shaping where a stack of metasurfaces, each supporting multiple independently controlled quasi-bound states in the continuum, molds the optical wavefront distinctively at multiple wavelengths and yet stay transparent over the rest of the spectrum. Such a platform is scalable to the visible for applications in augmented reality and transparent displays. Nonlocal metasurfaces are demonstrated that offer both spatial and spectral control of light, realizing metalenses focusing light exclusively over a narrowband resonance while leaving off-resonant frequencies unaffected.

C. Fabre, N. Treps

Quantum states of light are at the same time endowed with two superposition principles: the one of the classical Maxwell waves and the one of the quantum states occupying these waves. This article reviews the interplay between these two aspects of quantum optics. A summary of the description of multimode quantum states is presented along with an example of the characterization of correlations and entanglement with applications in metrology and quantum computation.

C. Minkenberg, Rajagopal Krishnaswamy, A. Zilkie et al.

Cyriel Minkenberg, Rockley Photonics Ltd., 57 Woodstock Road, Oxford, OX2 6HJ, UK Email: cyriel.minkenberg@rockleyphotonics.com Abstract High‐capacity, high‐density, power‐, and cost‐efficient optical links are undoubtedly of critical importance for datacenter infrastructure. However, the optics roadmap has come to a fork in the road: Is it right to continue on the tried and proven path of pluggable modules or is it time to adopt a new deployment model that involves co‐packaged optics? Herein, we aim to shed light on the trade‐offs involved, enabling technologies, paths to adoption, and potential impact on datacenter network architecture.

L. Caspani, C. Xiong, B. Eggleton et al.

The ability to generate complex optical photon states involving entanglement between multiple optical modes is not only critical to advancing our understanding of quantum mechanics but will play a key role in generating many applications in quantum technologies. These include quantum communications, computation, imaging, microscopy and many other novel technologies that are constantly being proposed. However, approaches to generating parallel multiple, customisable bi- and multi-entangled quantum bits (qubits) on a chip are still in the early stages of development. Here, we review recent advances in the realisation of integrated sources of photonic quantum states, focusing on approaches based on nonlinear optics that are compatible with contemporary optical fibre telecommunications and quantum memory platforms as well as with chip-scale semiconductor technology. These new and exciting platforms hold the promise of compact, low-cost, scalable and practical implementations of sources for the generation and manipulation of complex quantum optical states on a chip, which will play a major role in bringing quantum technologies out of the laboratory and into the real world. Several new platforms are promising for generating and manipulating complex quantum optical states on a chip. Chip-based sources of quantum states of light are needed to bring quantum technologies out of the lab and into the real world, but such sources are still immature. David Moss at Swinburne University of Technology, Australia, and an international team have reviewed progress in developing and characterizing such sources. Waveguide, cavity and ring resonator devices made from nonlinear materials such as silicon, silicon nitride, silicon oxynitride, Hydex and periodically poled lithium niobate offer scientists a rich variety of sources. Furthermore, many of these technologies can be integrated with silicon CMOS photonics, providing a path for building sophisticated, scalable optical integrated circuits for generating and manipulating quantum optical states for applications in quantum information processing and communications.

Peng Chen, Bingyan Wei, Wei Hu et al.

Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin–orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli‐responsive self‐assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC‐mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC‐based transmissive planar optical elements and chiral LC‐based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.

Jie Zhou, Mengchuan Ou, Bo Yuan et al.

The strangulation of intestinal obstruction (IO) presents challenges in the assessment of disease progression and surgical decision-making. Intraoperatively, an accurate evaluation of the status of the IO is critical for determining the extent of surgical resection. Dual-modality ultrasound/photoacoustic tomography (US/PAT) imaging has the potential to provide spatially resolved tissue oxygen saturation (SO₂), serving as a valuable marker for IO diagnosis. In this study, US/PAT was utilized for imaging rat models of IO, with the data used for reconstruction, statistical analysis, and distribution evaluation. Results showed that SO₂ decreased with increasing strangulation severity. Notably, the kurtosis and skewness of the SO₂ distribution outperformed SO₂ itself in diagnosis, as they more effectively capture the heterogeneity of SO₂ distribution. Kurtosis reflects distribution concentration, while skewness measures asymmetry, both achieving areas under the receiver operating characteristic curve (AUROC) of 0.969. In conclusion, US/PAT offers a rapid and convenient method for assessing strangulation in IO.

V. Torrelli, M. C. G. Alasio, M. D'Alessandro et al.

We investigate the robustness of single-mode (SM) emission in high-power, large-area rectangular vertical-cavity surface-emitting lasers (VCSELs), emphasizing the impact of self-heating effects. Compared to circular geometries, large-area rectangular VCSELs provide improved heat dissipation thanks to their high geometrical aspect ratio, and higher SM output power by means of their patterned reflectivity obtainable by an array of grating reliefs. Self-heating alters the refractive index of the device. We demonstrate, experimentally and numerically, how the related thermal lensing affects the transverse modes. By misaligning the antinodes of the promoted lasing mode and the surface reliefs, self-heating degrades SM operation if not properly accounted for in the relief position design. Combining thermal and optical models, we propose numerically optimized grating relief geometries ensuring robust SM emission across varying operating temperatures.