Hasil untuk "Optics. Light"

Xin‐Zhu Liu, Yan‐Han Yang, Manuel Gessner et al.

Quantum metrology establishes fundamental precision limits for parameter estimation, yet standard Quantum Cramér‐Rao Bound (QCRB) becomes insufficient in the finite‐data regime. In this article, the QCRB is systematically tighten using a hybrid classical‐quantum framework by incorporating generalized unbiasedness constraints through test observables. These frequentist bounds form a hierarchy converging asymptotically to the QCRB as more measurements are performed. These hierarchical frequentist bounds are validated for single‐qubit phase estimation on a photonic platform.

Samuel Nlend, Sune Von Solms, Johann Meyer

This paper explores the provision of an all-in-one IR-spectroscopy platform for nanoplastics as well as less than 10μ m microplastics size, aiming to surpass the current limit of 20μm. For such a multilevel spectroscopy, we propose an optical chopper configuration that produces multilevel modulation of laser source, and an induced anti-Stokes shift technique that adds energy in a sample assumed to contain microplastics, their degraded form, and their possible retention. We control reduction of the source energy flux using a splitter, and a linear edges’ chopper, whose windows alternate between empty and filled with a transmitting but high absorbance nanotube material spaces, while controlling the sample emission using an induced Anti-Stokes shift. This yields two methods: vibrational/rotational and electronic transitions. The first method provides us with the absorbance against energy of a sample assumed to contain compounds made of CC, CH, CO, CN, xH. The second method defines the set of lower bandpass of the assumed diffraction grating entry from the wavelengths emitted, from where the bandpass are derived. The new geometrical chopper’s configuration, and its transmitted signals for a flux distribution are given. The IR source energy and the induced hot-band, both suitable for the multilevel bandpass for the detection of nano/micro-plastics and their retained nanoparticles spectroscopy are discussed. We obtain bandpass by scaling down the wavelengths which vary only when both energy sources vary for any allowed atomic energy level, and we characterize the absorbance of nanoparticles components in near-IR region.

Dong Wang, Qikuan Cheng, Weibang Xia et al.

Abstract Constructing micro-/nanostructure-modulated photofields in upconversion devices to absorb low-energy photons and emit high-energy light is revolutionary for bioimaging, lasers, and photovoltaics, with proven capability to boost upconversion luminescence (UCL) by orders of magnitude. However, photoenergy dissipation and inadequate absorption result in excitation thresholds exceeding 1 mW/cm2, which exceeds retinal safety limits and hinders wearable upconversion optics. Here, we report the use of upconversion core-shell microsphere-induced infrared field convergence, NaYF4:Yb,Er shell-based resonant cavities for multiple reflection-absorption-upconversion and photonic crystal amplifiers to improve UCL intensity three orders of magnitude, and achieve ultralow threshold (0.0025 mW/cm2). The 500 nm upconversion core-shell microspheres generated 1200-fold stronger electric field through concentrated photofield and attained 8-fold infrared absorption with a forward/backward emission ratio of 150. Fabricated upconversion contact lenses significantly improved dark-light imaging clarity and vision restoration in retinal degeneration rabbits. Microsphere-mediated directional upconversion strategy maximizes photoenergy utilization, paving the way for high-performance wearable upconversion devices.

Chieri Okawa, Hiraku Okada, Tadahiro Wada

This study focuses on visible light communication using a high-speed display and rolling shutter camera. In conventional methods, data are arranged in vertical stripes, but the low transmission rate is a critical challenge. Herein, we improve the transmission rate by arranging data in a grid pattern. Owing to the characteristics of rolling shutter cameras, which are used as the receiver, the data loss rate increases. Therefore, we propose a method using error correction codes and conduct performance evaluation experiments. In the proposed method, the transmission data are encoded using error correction codes, and the packet structure is adapted to the capturing characteristics of the rolling shutter camera. Through experiments, we compared the conventional vertical stripe arrangement with the proposed grid arrangement and evaluated the impact of different code rates and lengths, demonstrating the feasibility of achieving higher transmission rates.

Linzhi Yu, Haobijam J. Singh, Jesse Pietila et al.

All-optical image processing offers a high-speed, energy-efficient alternative to conventional electronic systems by leveraging the wave nature of light for parallel computation. However, traditional optical processors rely on bulky components, limiting scalability and integration. Here, we demonstrate a compact metasurface-based platform for analog optical computing. By employing double-phase encoding and polarization multiplexing, our approach enables arbitrary image transformations within a single passive nanophotonic device, eliminating the need for complex optical setups or digital post-processing. We experimentally showcase key computational operations, including first-order differentiation, cross-correlation, vertex detection, and Laplacian differentiation. Additionally, we extend this framework to high-resolution 3D holography, achieving subwavelength-scale volumetric wavefront control for depth-resolved reconstructions with high fidelity. Our results establish a scalable and versatile approach to computational optics, with applications including real-time image processing, energy-efficient computing, biomedical imaging, high-fidelity holographic displays, and optical data storage, driving the advancement of intelligent optical processors.

Xiaoyu Zhao, Ke Sun, Siyuan Cui et al.

Over the last decades, continuous technological advancements have been made in III‐nitride light‐emitting diodes (LEDs), so that they are considered as a promising replacement of traditional light sources. With the emission wavelength covering the entire visible spectrum, InGaN LEDs find various applications such as solid‐state lightings, full‐color displays, and visible light communication. However, the quantum efficiency of InGaN LEDs suffers from a dramatic decline as the emission wavelength extends from blue to green–red region. This issue restrains the lighting and display applications based on the color‐mixing monolithic lighting source system. In this review, the recent breakthroughs in long‐wavelength InGaN LEDs, together with the challenges and approaches to realize high‐indium‐composition InGaN epilayers, are introduced. These cover the different epitaxial substrates, nucleation layers, and epitaxial structures, especially multiple quantum wells active region. The related studies are also discussed to improve the long‐wavelength LEDs performance from the aspect of crystal quality, growth orientation, carrier‐injection, and 3D nanostructures. Finally, current status and perspectives for future long‐wavelength LEDs development are proposed briefly.

Nemanja Jovanovic, Pradip Gatkine, Narsireddy Anugu et al.

Photonic technologies offer numerous functionalities that can be used to realize astrophotonic instruments. The most spectacular example to date is the ESO Gravity instrument at the Very Large Telescope in Chile that combines the light-gathering power of four 8 m telescopes through a complex photonic interferometer. Fully integrated astrophotonic devices stand to offer critical advantages for instrument development, including extreme miniaturization when operating at the diffraction-limit, as well as integration, superior thermal and mechanical stabilization owing to the small footprint, and high replicability offering significant cost savings. Numerous astrophotonic technologies have been developed to address shortcomings of conventional instruments to date, including for example the development of photonic lanterns to convert from multimode inputs to single mode outputs, complex aperiodic fiber Bragg gratings to filter OH emission from the atmosphere, complex beam combiners to enable long baseline interferometry with for example, ESO Gravity, and laser frequency combs for high precision spectral calibration of spectrometers. Despite these successes, the facility implementation of photonic solutions in astronomical instrumentation is currently limited because of (1) low throughputs from coupling to fibers, coupling fibers to chips, propagation and bend losses, device losses, etc, (2) difficulties with scaling to large channel count devices needed for large bandwidths and high resolutions, and (3) efficient integration of photonics with detectors, to name a few. In this roadmap, we identify 24 key areas that need further development. We outline the challenges and advances needed across those areas covering design tools, simulation capabilities, fabrication processes, the need for entirely new components, integration and hybridization and the characterization of devices. To realize these advances the astrophotonics community will have to work cooperatively with industrial partners who have more advanced manufacturing capabilities. With the advances described herein, multi-functional integrated instruments will be realized leading to novel observing capabilities for both ground and space based platforms, enabling new scientific studies and discoveries.

A. Devos, F. Chevreux, C. Licitra et al.

Colored Picosecond Acoustics (CPA) and Spectroscopic Ellipsometry (SE) are combined to measure elastic and thermoelastic properties of polymer thin-film resins deposited on 300 mm wafers. Film thickness and refractive index are measured using SE. Sound velocity and thickness are measured using CPA from the refractive index. Comparing the two thicknesses allows checking consistency between both approaches. The same combination is then applied at various temperatures from 19° to 180°C. As the sample is heated, both thickness and sound velocity change. By monitoring these contributions separately, the Temperature Coefficient on sound Velocity (TCV) and the Coefficient on Thermal Expansion are deduced. The protocol is applied to five industrial samples made of different thin-film resins currently used by microelectronic industry. Young’s modulus varies from resin to resin by up to 20%. TCV is large on each resin and varies from one resin to another up to 57%.

Igor Meglinski, Lingyan Shi, Hui Ma

Kang-Hyok O, Kwang-Hyon Kim

Marriage of the concepts of parity‐time (PT) symmetry and topology recently gave rise to PT‐symmetric topological photonics, triggering great interest in the community of photonics. This work reveals PT‐symmetric phase transition in second‐order topological photonic systems: the photonic systems consisting of square lattice topological photonic crystals with balanced gain and loss support the corner states, two of which are in thresholdless PT broken phase and the other two exhibit PT phase transition with a threshold determined by the coupling strength between the corner modes. The main advantage of the proposed photonic system is the significantly high gain contrast between the corner states and unnecessary background modes originating from bulk and edge ones, enabling diverse photonic applications such as nanolasing with significantly high power compared with the preceding topological nanolasers made of only gain sublattices. The results presented in this work pave the way toward potential applications such as biological sensing and spectroscopy at the nanoscale.

Dong Yang, Haifeng Hu, Han Gao et al.

Tightly focused vector fields, which can be generated by focusing a light beam through a high-numerical-aperture objective, play an important role in nano-optics research. How to fully characterize this kind of field in the subwavelength scale is a challenging but important task. The Mie scattering nanointerferometry technique has been proposed to reconstruct the tightly focused vector field accurately. In this work, we theoretically demonstrate that the technique can be realized by collecting the transmitted light with two orthogonal polarization states simultaneously. Therefore, when nanoparticles are employed to scan the fields to be measured, more information of the scattering field can be acquired in the far field. This is helpful for solving the linear inverse scattering problem by reducing the number of scanning points, thus making the measurement more efficient.

Magdalena Furman, Rafał Mirek, Mateusz Król et al.

The insensitivity of photons towards external magnetic fields forms one of the hardest barriers against efficient magneto-optical control, aiming at modulating the polarization state of light. However, there is even scarcer evidence of magneto-optical effects that can spatially modulate light. Here, we demonstrate the latter by exploiting strongly coupled states of semimagnetic matter and light in planar semiconductor microcavities. We nonresonantly excite two spatially adjacent exciton-polariton condensates which, through inherent ballistic near field coupling mechanism, spontaneously synchronise into a dissipative quantum fluidic supermode of definite parity. Applying a magnetic field along the optical axis, we continuously adjust the light-matter composition of the condensate exciton-polaritons, inducing a supermode switch into a higher order mode of opposite parity. Our findings set the ground towards magnetic spatial modulation of nonlinear light.

M. Khorasaninejad, K. Crozier

A. Zayats, I. Smolyaninov

Michael Reitz, Christian Sommer, Claudiu Genes

Quantum cooperativity is evident in light-matter platforms where quantum-emitter ensembles are interfaced with confined optical modes and are coupled via the ubiquitous electromagnetic quantum vacuum. Cooperative effects can find applications, among other areas, in topological quantum optics, in quantum metrology, or in quantum information. This tutorial provides a set of theoretical tools to tackle the behavior responsible for the onset of cooperativity by extending open quantum system dynamics methods, such as the master equation and quantum Langevin equations, to electron-photon interactions in strongly coupled and correlated quantum-emitter ensembles. The methods are illustrated on a wide range of current research topics such as the design of nanoscale coherent-light sources, highly reflective quantum metasurfaces, or low intracavity power superradiant lasers.

Xiaoyang Chang, Wenxiu Li, Hao Zhang et al.

Optical gyroscope based on the Sagnac effect have excellent potential in the application of high-sensitivity inertial rotation sensors. In this paper, we demonstrate that for an optical resonance gyroscope with normal dispersion, the measurement sensitivity can be increased by two orders of magnitude through coupling into a squeezed vacuum light, which is different from that in the classical situation. When the system is operated under critical anomalous dispersion condition, injecting a squeezed vacuum light allows the measurement sensitivity beyond the corresponding standard quantum limit by five orders of magnitude, with a minimum value of 3.8*10^-5 Hz. This work offers a promising possibility for developing optical gyroscopes that combine high sensitivity with tiny size.

Sameen Ahmed Khan, Ramaswamy Jagannathan

We derive a new eight dimensional matrix representation of the Maxwell equations for a linear homogeneous medium and extend it to the case of a linear inhomogneous medium. This derivation starts ab initio with the Maxwell equations and uses arguments based on the algebra of the Pauli matrices. This process leads automatically to the matrix representation based on the Riemann-Silberstein-Weber (RSW) vector. The new representation for the homogeneous medium is a direct sum of four Pauli matrix blocks. This aspect of the new representation should make it suitable for studying the propagation of electromagnetic waves in a linear inhomogeneous medium adopting the techniques of quantum mechanics treating the inhomogeneity as a perturbation. The new representation is used to rederive the Mukunda-Simon-Sudarshan matrix substitution rule for transition from the Helmholtz scalar wave optics to the Maxwell vector wave optics.

Taoying Yu, Xuesong Liu, Andrey Pryamikov et al.

In this paper, compression of high-power femtosecond pulses in Sagnac interferometers constructed of anti-resonant hollow core fibers (ARHCF) is investigated numerically and experimentally. By varying the types and pressures of gas filled in the hollow core fiber, the group velocity dispersion and the nonlinear pulse phase accumulation difference between clockwise and counterclockwise propagations could be tuned conveniently. In experiment, we demonstrate the pedestal suppression temporal pulse compression of 800 nm, 160 fs, 10 μJ pulses from a Ti: Sapphire laser at 1 kHz to 20 fs with maximum compression efficiency of 25% nearly and compression ratio of eight.

Angelos Karlas, Michael Kallmayer, Michael Bariotakis et al.

Several imaging techniques aim at identifying features of carotid plaque instability but come with limitations, such as the use of contrast agents, long examination times and poor portability. Multispectral optoacoustic tomography (MSOT) employs light and sound to resolve lipid and hemoglobin content, both features associated with plaque instability, in a label-free, fast and highly portable way. Herein, 5 patients with carotid atherosclerosis, 5 healthy volunteers and 2 excised plaques, were scanned with handheld MSOT. Spectral unmixing allowed visualization of lipid and hemoglobin content within three ROIs: whole arterial cross-section, plaque and arterial lumen. Calculation of the fat-blood-ratio (FBR) value within the ROIs enabled the differentiation between patients and healthy volunteers (P = 0.001) and between plaque and lumen in patients (P = 0.04). Our results introduce MSOT as a tool for molecular imaging of human carotid atherosclerosis and open new possibilities for research and clinical assessment of carotid plaques.

Giovanni Donati, Claudio R. Mirasso, Mattia Mancinelli et al.

Microring resonators (MRRs) are a key photonic component in integrated devices, due to their small size, low insertion losses, and passive operation. While the MRRs have been established for optical filtering in wavelength-multiplexed systems, the nonlinear properties that they can exhibit give rise to new perspectives on their use. For instance, they have been recently considered for introducing optical nonlinearity in photonic reservoir computing systems. In this work, we present a detailed numerical investigation of a silicon MRR operation, in the presence of external optical feedback, in a time delay reservoir computing scheme. We demonstrate the versatility of this compact, passive device, by exploiting different operating regimes and solving computing tasks with diverse memory requirements. We show that when large memory is required, as it occurs in the Narma 10 task, the MRR nonlinearity does not play a significant role when the photodetection nonlinearity is involved, while the contribution of the external feedback is significant. On the contrary, for computing tasks such as the Mackey-Glass and the Santa Fe chaotic timeseries prediction, the MRR and the photodetection nonlinearities contribute both to efficient computation. The presence of optical feedback improves the prediction of the Mackey-Glass timeseries while it plays a minor role in the Santa Fe timeseries case.