Hasil untuk "Optics. Light"

Anton Frisk Kockum, A. Miranowicz, S. De Liberato et al.

Light–matter coupling with strength comparable to the bare transition frequencies of the system is called ultrastrong. This Review surveys how experiments have realized ultrastrong coupling in the past decade, the new phenomena predicted in this regime and the applications it enables. Ultrastrong coupling between light and matter has, in the past decade, transitioned from a theoretical idea to an experimental reality. It is a new regime of quantum light–matter interaction, which goes beyond weak and strong coupling to make the coupling strength comparable to the transition frequencies in the system. The achievement of weak and strong coupling has led to increased control of quantum systems and to applications such as lasers, quantum sensing, and quantum information processing. Here we review the theory of quantum systems with ultrastrong coupling, discussing entangled ground states with virtual excitations, new avenues for nonlinear optics, and connections to several important physical models. We also overview the multitude of experimental setups, including superconducting circuits, organic molecules, semiconductor polaritons, and optomechanical systems, that have now achieved ultrastrong coupling. We conclude by discussing the many potential applications that these achievements enable in physics and chemistry. Ultrastrong coupling (USC) can be achieved by coupling many dipoles to light, or by using degrees of freedom whose coupling is not bounded by the smallness of the fine-structure constant. The highest light–matter coupling strengths have been measured in experiments with Landau polaritons in semiconductor systems and in setups with superconducting quantum circuits. With USC, standard approximations break down, allowing processes that do not conserve the number of excitations in the system, leading to a ground state that contains virtual excitations. Potential applications of USC include fast and protected quantum information processing, nonlinear optics, modified chemical reactions and the enhancement of various quantum phenomena. Now that USC has been reached in several systems, it is time to experimentally explore the new phenomena predicted for this regime and to find their useful applications. Ultrastrong coupling (USC) can be achieved by coupling many dipoles to light, or by using degrees of freedom whose coupling is not bounded by the smallness of the fine-structure constant. The highest light–matter coupling strengths have been measured in experiments with Landau polaritons in semiconductor systems and in setups with superconducting quantum circuits. With USC, standard approximations break down, allowing processes that do not conserve the number of excitations in the system, leading to a ground state that contains virtual excitations. Potential applications of USC include fast and protected quantum information processing, nonlinear optics, modified chemical reactions and the enhancement of various quantum phenomena. Now that USC has been reached in several systems, it is time to experimentally explore the new phenomena predicted for this regime and to find their useful applications.

A. Rauschenbeutel

N. Rubin, Gabriele D'Aversa, P. Chevalier et al.

A metasurface polarization camera Imaging the polarization of light scattered from an object provides an additional degree of freedom for gaining information from a scene. Conventional polarimeters can be bulky and usually consist of mechanically moving parts (with a polarizer and analyzer setup rotating to reveal the degree of polarization). Rubin et al. designed a metasurface-based full-Stokes compact polarization camera without conventional polarization optics and without moving parts. The results provide a simplified route for polarization imaging. Science, this issue p. eaax1839 A metasurface array is designed that can operate as a polarization camera INTRODUCTION Polarization describes the path along which light’s electric field vector oscillates. An essential quality of electromagnetic radiation, polarization is often omitted in its mathematical treatment. Nevertheless, polarization and its measurement are of interest in almost every area of science, as well as in imaging technology. Traditional cameras are sensitive to intensity alone, but in a variety of contexts, knowledge of polarization can reveal features that are otherwise invisible. Determination of the full-Stokes vector—the most complete description of light’s polarization—necessitates at least four individual measurements. This results in optical systems that are often bulky, reliant on moving parts, and limited in time resolution. RATIONALE We introduce a formalism—matrix Fourier optics—for treating polarization in paraxial diffractive optics. This formalism is a powerful generalization of a large body of past work on optical elements in which polarization may vary spatially. Moreover, it suggests a path to realizing many polarization devices in parallel using a single optical element. We can then design diffraction gratings whose orders behave as polarizers for an arbitrarily selected set of polarization states, a new class of optical element. The intensity of light on a set of diffraction orders is then dictated by the polarization of the illuminating light, making these gratings immediately applicable to full-Stokes polarization imaging. RESULTS We theoretically investigate these gratings and develop an optimization scheme for their design. Our diffraction gratings were realized with dielectric metasurfaces in which subwavelength, anisotropic structures provide for tunable polarization control at visible frequencies. Characterization of the fabricated gratings shows that they perform as designed. Notably, an arbitrary set of polarizations may be analyzed by a single unit cell, in contrast to past approaches that relied on interlacing of several individually designed diffraction gratings, increasing the flexibility of these devices. These gratings enable a snapshot, full-Stokes polarization camera—a camera acquiring images in which the full polarization state is known at each pixel—with no traditional polarization optics and no moving parts (see panel A of the figure). Polarized light from a photographic scene is incident on the grating inside of a camera. The polarization is “sorted” by the specially designed subwavelength metasurface grating. When combined with imaging optics (a lens) and a sensor, four copies of the image corresponding to four diffraction orders are formed on the imaging sensor. These copies have each, effectively, passed through a different polarizer whose functions are embedded in the metasurface. The four images can be analyzed pixel-wise to reconstruct the four-element Stokes vector across the scene. Several examples are shown at 532 nm, both indoors and outdoors. The figure depicts an example photograph of two injection-molded plastic pieces, a ruler and a spoon (illuminated by a linearly polarized backlight), that show in-built stresses (see panels C to E of the figure) that are not evident in a traditional photograph (panel B). The camera is compact, requiring only the grating (which is flat and monolithically integrated, handling all the polarization analysis in the system), a lens, and a conventional CMOS (complementary metal–oxide–semiconductor) sensor. CONCLUSION Metasurfaces can therefore simplify and compactify the footprint of optical systems relying on polarization optics. Our design formalism suggests future research directions in polarization optics. Moreover, it enables a snapshot, full-Stokes polarization imaging system with no moving parts, no bulk polarization optics, and no specially patterned camera pixels that is not altogether more complicated than a conventional imaging system. Our hardware may enable the adoption of polarization imaging in applications (remote sensing, atmospheric science, machine vision, and even onboard autonomous vehicles) where its complexity might otherwise prove prohibitive. Metasurface-based polarization camera. (A) Photographic scenes contain polarized light that is invisible to traditional, intensity-based imaging, which may reveal hidden features. Our camera uses a metasurface (inset) that directs incident light depending on its polarization, forming four copies of an image that permit polarization reconstruction. (B to E) A plastic ruler and spoon are photographed with the camera. (B) A monochrome intensity image (given by the S0 component of the Stokes vector) does not reveal the rich polarization information stemming from stress-birefringence readily evident in (C) to (E), which show a raw exposure, azimuth of the polarization ellipse, and the S3 component of the Stokes vector that describes circular polarization content, respectively. Recent developments have enabled the practical realization of optical elements in which the polarization of light may vary spatially. We present an extension of Fourier optics—matrix Fourier optics—for understanding these devices and apply it to the design and realization of metasurface gratings implementing arbitrary, parallel polarization analysis. We show how these gratings enable a compact, full-Stokes polarization camera without standard polarization optics. Our single-shot polarization camera requires no moving parts, specially patterned pixels, or conventional polarization optics and may enable the widespread adoption of polarization imaging in machine vision, remote sensing, and other areas.

L. Novotný, B. Hecht

Research in optics and photonics, in parallel with the rapid development of nanoscience, has driven advancements within many fields of contemporary science and technology, allowing nano-optics to flourish as a research field. This authoritative text provides a comprehensive and accessible account of this important topic, beginning with the theoretical foundations of light localization and the propagation and focusing of optical fields, before progressing to more advanced topics such as near-field optics, surface plasmons in noble metals, metamaterials, and quantum emitters. Now in its third edition, the book has been substantially restructured, expanded, and developed to include additional problem sets and important topics such as super-resolution microscopy, random media, and coupled-mode theory. It remains an essential resource for graduate students and researchers working in photonics, optoelectronics, and nano-optics.

W. Barnes, A. Dereux, T. Ebbesen

R. Minck, R. Terhune, C. C. Wang

Paul Kubelka

M. Fleischhauer, A. Imamoğlu, J. Marangos

J. Ramus, J. Kirk

Chao He, Honghui He, Jintao Chang et al.

Many polarisation techniques have been harnessed for decades in biological and clinical research, each based upon measurement of the vectorial properties of light or the vectorial transformations imposed on light by objects. Various advanced vector measurement/sensing techniques, physical interpretation methods, and approaches to analyse biomedically relevant information have been developed and harnessed. In this review, we focus mainly on summarising methodologies and applications related to tissue polarimetry, with an emphasis on the adoption of the Stokes–Mueller formalism. Several recent breakthroughs, development trends, and potential multimodal uses in conjunction with other techniques are also presented. The primary goal of the review is to give the reader a general overview in the use of vectorial information that can be obtained by polarisation optics for applications in biomedical and clinical research. The review focuses on methodologies and biomedical applications of polarisation optics. It also presents prospects on development trends, the potential multi-modal uses in conjunction with other techniques.

A. Dorrah, N. Rubin, Aun Zaidi et al.

Yijie Shen, Qiang Zhang, Peng Shi et al.

Skyrmions are topologically stable quasiparticles that have been predicted and demonstrated in quantum fields, solid-state physics and magnetic materials, but only recently observed in electromagnetic fields. Here we review the recent advances in optical skyrmions within a unified topological framework. Starting from fundamental theories and classification of skyrmionic states, we describe generation and topological control of different kinds of skyrmions in evanescent, structured and spatiotemporal optical fields. We further highlight generalized classes of optical topological quasiparticles beyond skyrmions and outline the emerging applications, future trends and open challenges. A complex vectorial field structure of optical quasiparticles with versatile topological characteristics emerges as an important feature in modern spin optics, imaging, metrology, optical forces, structured light, and topological and quantum technologies. Advances in the understanding of optical skyrmions, within a unified topological framework, are reviewed. The field structure of such optical quasiparticles, and their topological characteristics, may be useful for fields ranging from imaging to quantum technologies.

Ethan Tseng, S. Colburn, James E. M. Whitehead et al.

Nano-optic imagers that modulate light at sub-wavelength scales could enable new applications in diverse domains ranging from robotics to medicine. Although metasurface optics offer a path to such ultra-small imagers, existing methods have achieved image quality far worse than bulky refractive alternatives, fundamentally limited by aberrations at large apertures and low f-numbers. In this work, we close this performance gap by introducing a neural nano-optics imager. We devise a fully differentiable learning framework that learns a metasurface physical structure in conjunction with a neural feature-based image reconstruction algorithm. Experimentally validating the proposed method, we achieve an order of magnitude lower reconstruction error than existing approaches. As such, we present a high-quality, nano-optic imager that combines the widest field-of-view for full-color metasurface operation while simultaneously achieving the largest demonstrated aperture of 0.5 mm at an f-number of 2. While meta-optics have the potential to dramatically miniaturize camera technology, the quality of the captured images remains poor. Co-designing a single meta-optic and software correction, here the authors report on full-color imaging with quality comparable to commercial cameras.

M. Chen, Xiaoyuan Liu, Yanni Sun et al.

Recent years have witnessed promising artificial intelligence (AI) applications in many disciplines, including optics, engineering, medicine, economics, and education. In particular, the synergy of AI and meta-optics has greatly benefited both fields. Meta-optics are advanced flat optics with novel functions and light-manipulation abilities. The optical properties can be engineered with a unique design to meet various optical demands. This review offers comprehensive coverage of meta-optics and artificial intelligence in synergy. After providing an overview of AI and meta-optics, we categorize and discuss the recent developments integrated by these two topics, namely AI for meta-optics and meta-optics for AI. The former describes how to apply AI to the research of meta-optics for design, simulation, optical information analysis, and application. The latter reports the development of the optical Al system and computation via meta-optics. This review will also provide an in-depth discussion of the challenges of this interdisciplinary field and indicate future directions. We expect that this review will inspire researchers in these fields and benefit the next generation of intelligent optical device design.

Zhenyi Luo, Yannanqi Li, John Semmen et al.

Diffractive liquid-crystal optics is a promising optical element for virtual reality (VR) and mixed reality as it provides an ultrathin formfactor and lightweight for human factors and ergonomics. However, its severe chromatic aberrations impose a big challenge for full-color display applications. In this study, we demonstrate an achromatic diffractive liquid-crystal device to overcome this longstanding chromatic aberration issue. The proposed device consists of three stacked diffractive liquid crystal optical elements with specifically designed spectral response and polarization selectivity. The concept is validated by both simulations and experiments. Our experimental results show a significant improvement in imaging performance with two types of light engines: a laser projector and an organic light-emitting diode display panel. In addition, our simulation results indicate that the lateral color shift is reduced by ~100 times in comparison with conventional broadband diffractive liquid-crystal lens. Potential applications for VR-enabled metaverse, spatial computing, and digital twins that have found widespread applications in smart tourism, smart education, smart healthcare, smart manufacturing, and smart construction are foreseeable. An achromatic diffractive liquid crystal optics system has been demonstrated to overcome the longstanding chromatic aberration issue, which provides more compact optical components for a wide range of applications.

Zhenyue Chen, Yi Chen, Irmak Gezginer et al.

Abstract A critical gap currently exists in systematic understanding and experimental validation of the role of astrocytes in neurovascular coupling and their functional links with other brain cells. Despite a broad selection of functional neuroimaging tools for multi-scale brain interrogations, no methodology currently exists that can discern responses from neural and glial cells while simultaneously mapping the associated hemodynamic activity on a large scale. We present a hybrid multiplexed fluorescence and magnetic resonance imaging (HyFMRI) platform for measuring neuronal and astrocytic activity registered to concurrently recorded brain-wide hemodynamic responses. It features a fiberscope-based imaging system for multichannel fluorescence and optical intrinsic signal recordings and a custom surface radiofrequency coil, which are incorporated into the bore of a preclinical magnetic resonance imaging (MRI) scanner. We used HyFMRI to study peripheral-stimulus-evoked brain responses in mice differentially labeled with RCaMP and GCaMP genetically-encoded calcium indicators. Stimulation-evoked neuronal responses displayed the fastest kinetics and highest activation amplitude followed by astrocytic signals and the hemodynamic responses simultaneously recorded with functional MRI. In addition, the activation traces from neurons and astrocytes exhibited high linear correlation, thus providing direct evidence of astrocytic mediation in neurovascular coupling. This newly developed capacity to capture cell-type-specific calcium signaling alongside whole-brain hemodynamics enables the simultaneous investigation of neuro-glial-vascular interactions in health and disease. HyFMRI thus expands the current neuroimaging toolbox for a wide range of studies into synaptic plasticity, neural circuitry, brain function and disorders.

Bai Zhang, Zhenqing Jiang, Zipeng Yin et al.

Angle measurement technology, an essential geometric measurement technique, has extensive applications in manufacturing, aerospace, and other fields. It has become a focal point in the research of measurement technology. The novel optical angular sensor that adopts multiple optical arm amplification technology is presented in this paper. The system is equipped with a dual-layer pyramid reflector configuration. This configuration takes advantage of multiplicative light path reflection effects to amplify angular displacements. The reflection laser displacement is detected by using a position-sensitive detector (PSD), effectively converting angular measurements into linear displacement parameters. By alternating measurement of multiple measuring units, continuous high-precision angle measurement can be achieved. Experimental verification has confirmed the technical feasibility of this multiple optical arm amplification principle. Prototype testing shows that the sensor can achieve an accuracy of ±0.5″ under standard operating conditions. The continuous measurement principle of the angle sensor prototype is verified by the alternating measurement of multiple measuring units with two adjacent groups of reflective surfaces. The proposed measurement principle offers a low-cost and high-precision solution for angle measurement.

Jan Sova, Marie Kolaříková

The radiometric integral is the fundamental radiance--to--flux relation in imaging, whereas étendue is typically used as a compact system-level descriptor. For quantitative imaging and calibration, however, the operative mapping must be explicit at the level of individual detector pixels, including pixel acceptance and field-dependent pupil visibility. This work packages the pixel-restricted radiometric integral into a reusable geometric throughput factor by defining a per-pixel optogeometric (optical-throughput) factor $F_{\mathrm{opg},i}$ (units \si{m^2.sr}) such that, under weak radiance variation, $Φ_i \approx L_i\,F_{\mathrm{opg},i}$. Making throughput explicit at the pixel scale yields an optics-delivered photon budget in which the incident photon count at the detector, $N_{\mathrm{inc},i}$ (before quantum efficiency), scales linearly with geometry: $N_{\mathrm{inc},i}\propto F_{\mathrm{opg},i}$ for a given scene radiance distribution and fixed acquisition settings (bandwidth, integration time, and optical transmission). The corresponding optics-delivered (pre-detection) shot-noise ceiling is set by the incident photon count $N_{\mathrm{inc},i}$, with $\mathrm{SNR}_{\mathrm{inc},i}\le \sqrt{N_{\mathrm{inc},i}}\propto \sqrt{F_{\mathrm{opg},i}}$, while in photoelectron units one has $\mathrm{SNR}_i \le \sqrt{N_{\mathrm{ph},i}}=\sqrt{η(\barν)\,N_{\mathrm{inc},i}}\propto \sqrt{F_{\mathrm{opg},i}}$, where $N_{\mathrm{ph},i}$ is the detected photoelectron count and $η(\barν)$ is the (narrowband) quantum efficiency; additional detector/electronics noise sources (e.g.\ dark current and read noise) can only reduce the achieved SNR below these shot-noise limits.

Pujing Zhang, Xue Hao, Qingli Zhou et al.

Mixed-dimensional van der Waals systems could improve terahertz modulators’ performance by utilizing the advantages of different dimensional materials. However, the reported available mixed-dimensional heterojunctions using two-dimensional (2D) and three-dimensional materials usually sacrifice the modulation speed to realize a higher modulation depth. Here, we creatively integrate one-dimensional (1D) nanowires with 2D nanofilms to construct the novel mixed-dimensional tellurium (Te) homojunction and achieve optimal indices with an ultrahigh modulation depth and a shorter carrier lifetime. In addition, a Te-based large-array imaging element was fabricated to successfully reproduce the painting colors under specific pump conditions as well as the dynamic multicolor display. Further measurements with the introduction of metamaterials prove that the required energy consumption can be significantly reduced by one order of magnitude. Our proposed 1D/2D integration strategy opens a new way to build high-performance terahertz functional devices and greatly expands the application fields of Te nanomaterials.

Lingmei Kong, Yun Luo, Qianqian Wu et al.

Abstract Light-emitting diodes (LEDs) based on perovskite semiconductor materials with tunable emission wavelength in visible light range as well as narrow linewidth are potential competitors among current light-emitting display technologies, but still suffer from severe instability driven by electric field. Here, we develop a stable, efficient and high-color purity hybrid LED with a tandem structure by combining the perovskite LED and the commercial organic LED technologies to accelerate the practical application of perovskites. Perovskite LED and organic LED with close photoluminescence peak are selected to maximize photon emission without photon reabsorption and to achieve the narrowed emission spectra. By designing an efficient interconnecting layer with p-type interface doping that provides good opto-electric coupling and reduces Joule heating, the resulting green emitting hybrid LED shows a narrow linewidth of around 30 nm, a peak luminance of over 176,000 cd m−2, a maximum external quantum efficiency of over 40%, and an operational half-lifetime of over 42,000 h.