Hasil untuk "Optics. Light"

T. Durduran, R. Choe, W. Baker et al.

Cheng Wang, Teng Zhang, Wenbin Lin

R. Loudon, M. Scully

R. Horstmeyer, H. Ruan, Changhuei Yang

L. Tian, L. Waller

Realizing high resolution across large volumes is challenging for 3D imaging techniques with high-speed acquisition. Here, we describe a new method for 3D intensity and phase recovery from 4D light field measurements, achieving enhanced resolution via Fourier ptychography. Starting from geometric optics light field refocusing, we incorporate phase retrieval and correct diffraction artifacts. Further, we incorporate dark-field images to achieve lateral resolution beyond the diffraction limit of the objective (5× larger NA) and axial resolution better than the depth of field, using a low-magnification objective with a large field of view. Our iterative reconstruction algorithm uses a multislice coherent model to estimate the 3D complex transmittance function of the sample at multiple depths, without any weak or single-scattering approximations. Data are captured by an LED array microscope with computational illumination, which enables rapid scanning of angles for fast acquisition. We demonstrate the method with thick biological samples in a modified commercial microscope, indicating the technique’s versatility for a wide range of applications.

S. Harris, L. Hau

Shaowei Liu, Dezhong Zhang, Lei Wang et al.

Abstract The integration of crystallographic control into solution-processed perovskite films remains a challenge for efficient light emission, as disordered optical dipoles fundamentally limit photon extraction, a bottleneck constraining both classical and quantum planar optoelectronic devices. Here, we address this by developing an in situ formation strategy for oriented quasi-2D perovskite nanosheets within films via ligand-engineered crystallization. By designing and orchestrating steric hindrance and π–π interactions of ligands, we direct the crystallization kinetics to yield regular face-on nanosheets exhibiting enhanced horizontal transition dipole moment orientation compared to conventional isotropic films. The in situ architectural control also elevates both the photoluminescence quantum yield beyond 90% and carrier mobility comparable to 3D perovskite levels. These synergies enable perovskite light-emitting diodes (PeLEDs) with an external quantum efficiency (EQE) of 31.2% for pure-red emission at 635 nm, comparing favorably to other pure-red PeLEDs. Concurrently, the peak luminance and operational stability of the in situ nanosheet PeLEDs exhibit significant improvements.

Musa N. Hamza, Mohammad Tariqul Islam, Sunil Lavadiya et al.

This paper addresses the challenge of early-stage cancer diagnosis using microwave imaging (MWI) techniques by targeting circulating exosomes, recently identified as promising cancer biomarkers. We introduce an innovative nano-photonic perfect absorber (NPA) operating in the terahertz (THz) range, offering a significant improvement over existing MWI-based approaches in terms of simplicity, sensitivity, and specificity. Unlike previous THz absorbers, the proposed NPA achieves an exceptionally wide operating bandwidth from 100 GHz to 50 THz with an absorption efficiency exceeding 97.5%, while featuring an ultra-compact nanoscale footprint (100 × 100 nm², thickness 30 nm). The design integrates a silver (Ag) resonator and a nickel (Ni) ground plane on a silicon dioxide (SiO₂) substrate, with meticulously tuned geometries to create multiple resonance modes, enabling continuous broadband absorption. Full-wave electromagnetic simulations validate the structure’s performance, including electric and magnetic field distributions, surface currents, and scattering parameters. Comparative analysis with state-of-the-art absorbers demonstrates the superior bandwidth, absorption stability, and angular robustness of our device. Furthermore, we demonstrate the NPA’s unique ability to act as a label-free biosensor for exosome detection, where cancerous exosomes consistently induce stronger electric field responses than normal exosomes due to their distinct molecular compositions. These results confirm the proposed NPA as a novel, highly effective platform for non-invasive, early-stage cancer diagnostics via MWI.

Lu Qian, Yamin Yang, Pan Chen et al.

Purpose: The major limitation of tumor microwave ablation (MWA) operation is the lack of predictability of the ablation zone before surgery. Operators rely on their individual experience to select a treatment plan, which is prone to either inadequate or excessive ablation. This paper aims to establish an ablation prediction model that guides MWA tumor surgical planning. Methods: An MWA process was first simulated by incorporating electromagnetic radiation equations, thermal equations, and optimized biological tissue parameters (dynamic dielectric and thermophysical parameters). The temperature distributions (the short/long diameters, and the total volume of the ablation zone) were then generated and verified by 60 cases ex vivo porcine liver experiments. Subsequently, a series of data were obtained from the simulated temperature distributions and to further fit the novel ablation coagulated area prediction model (ACAPM), thus rendering the ablation-dose table for the guiding surgical plan. The MWA clinical patient data and clinical devices suggested data were used to validate the accuracy and practicability of the established predicted model. Results: The 60 cases ex vivo porcine liver experiments demonstrated the accuracy of the simulated temperature distributions. Compared to traditional simulation methods, our approach reduces the long-diameter error of the ablation zone from 1.1[Formula: see text]cm to 0.29[Formula: see text]cm, achieving a 74% reduction in error. Further, the clinical data including the patients’ operation results and devices provided values were consistent well with our predicated data, indicating the great potential of ACAPM to assist preoperative planning.

Marina Romanova, Sergii Chertopalov, Yuri Dekhtyar et al.

The charge trapping phenomenon in the SiO2 layer of Si/SiO2 substrates during the electron beam deposition of CaF2 thin films of varying thicknesses (50–277 nm) was studied. Photoelectron emission (PE) spectroscopy was employed to analyze electron trapping mechanisms induced by the deposition process. Distinct peaks corresponding to electron traps in the SiO2 layer were identified in the PE spectra of CaF2 films. The intensity of these peaks varied with the film thickness and the accumulated electron irradiation dose. The study also investigated the relaxation of the PE spectra in both vacuum and air environments. In a vacuum, the PE peaks and integrated PE intensity remained stable for at least 24 h for CaF2 films of all thicknesses. When exposed to air, the PE peaks persisted for several days in films 125 nm thick or thinner but relaxed within several hours in 277 nm films. This rapid relaxation was attributed to a relatively high irradiation dose (about 2.5 mC) obtained during the fabrication of the 277 nm film, leading to an increased concentration of ionized F centers at the SiO2–CaF2 interface and the formation of (O2–-VA) centers upon air exposure. The relaxation of the PE spectrum intensity was attributed to electron transfer from SiO2 traps to (O2–-VA) centers. Furthermore, the possibility of a 260 nm electron escape depth for CaF2 material was confirmed.

Jesús E. Gómez-Correa, Brian Vohnsen, Barbara K. Pierścionek et al.

The field of visual and physiological optics is undergoing continuous significant advancements, driven by a deeper understanding of the human visual system and the development of cutting-edge optical technologies. This Roadmap, authored by leading experts, delves into critical areas such as corneal biomechanical properties, keratoconus, and advancements in corneal imaging and elastography. It explores the intricate structure-function relationship within the eye lens, offering new perspectives through lens models and ray tracing techniques. The document also covers advancements in retinal imaging, highlighting the current state and future directions, and the role of adaptive optics in evaluating retinal structure and function in both healthy and diseased eyes. Furthermore, it addresses the modelling of ocular surfaces using different mathematical functions and examines the factors affecting peripheral image quality in the human eye, emphasizing the importance of these aspects in visual performance. Additional topics include schematic and functional models of the human eye, the impact of optical and chromatic aberrations, and the design of contact, and intraocular lenses. Finally, the Roadmap addresses the intersection of neurosciences with vision health, presenting a comprehensive overview of current research and future trends aimed at improving visual health and optical performance. Ultimately, this Roadmap aims to serve as a valuable resource for ophthalmologists, optometrists, vision scientists, and engineers dedicated to advancing the field of visual and physiological optics.

Qianke Wang, Jun Liu, Dawei Lyu et al.

Abstract While the spatial mode of photons is widely used in quantum cryptography, its potential for quantum computation remains largely unexplored. Here, we showcase the use of the multi-dimensional spatial mode of photons to construct a series of high-dimensional quantum gates, achieved through the use of diffractive deep neural networks (D2NNs). Notably, our gates demonstrate high fidelity of up to 99.6(2)%, as characterized by quantum process tomography. Our experimental implementation of these gates involves a programmable array of phase layers in a compact and scalable device, capable of performing complex operations or even quantum circuits. We also demonstrate the efficacy of the D2NN gates by successfully implementing the Deutsch algorithm and propose an intelligent deployment protocol that involves self-configuration and self-optimization. Moreover, we conduct a comparative analysis of the D2NN gate’s performance to the wave-front matching approach. Overall, our work opens a door for designing specific quantum gates using deep learning, with the potential for reliable execution of quantum computation.

Olusola Akinbami, Thelma Majola, Grace Nomthandazo Ngubeni et al.

The search for alternatives to Pb‐based perovskites, due to concerns about stability and toxicity, has led to the exploration of Pb‐free options. Tin (Sn) and bismuth (Bi) are promising candidates, given their similar ionic radii to Pb and the isoelectronic nature of Pb2+ and Bi3+, which suggest comparable chemical properties. Among these, CsSnBr3 and Cs3Bi2Br9 are relatively underexplored but offer lower toxicity and enhanced stability while demonstrating optoelectronic properties suitable for various applications. In this study, CsSnBr3 and Cs3Bi2Br9 nanocrystals are synthesized using a colloidal method and integrated into Schottky diodes. X‐ray photoelectron spectroscopy analysis of the surface chemistry confirms improved thermal and phase stability compared to Pb‐based perovskites. Schottky diode parameters, including ideality factor, barrier height, and series resistance are assessed using conventional thermionic emission, modified Cheung's, and Norde's models. The Cs3Bi2Br9‐based Schottky diode exhibits superior electrical performance with the lowest series resistance and optimal barrier height. Electrical impedance spectroscopy results indicated that CsSnBr3 has higher resistances and lower capacitances than Cs3Bi2Br9, reflecting lower charge carrier mobility and more defects, although the R1C1 regions in both materials demonstrated faster charge dynamics, making them ideal for high‐speed applications.

Zhi-Gang Hu, Yi-Meng Gao, Jian-Fei Liu et al.

Abstract Cavity optomechanical systems have enabled precision sensing of magnetic fields, by leveraging the optical resonance-enhanced readout and mechanical resonance-enhanced response. Previous studies have successfully achieved mass-produced and reproducible microcavity optomechanical magnetometry (MCOM) by incorporating Terfenol-D thin films into high-quality (Q) factor whispering gallery mode (WGM) microcavities. However, the sensitivity was limited to 585 pT Hz−1/2, over 20 times inferior to those using Terfenol-D particles. In this work, we propose and demonstrate a high-sensitivity and mass-produced MCOM approach by sputtering a FeGaB thin film onto a high-Q SiO2 WGM microdisk. Theoretical studies are conducted to explore the magnetic actuation constant and noise-limited sensitivity by varying the parameters of the FeGaB film and SiO2 microdisk. Multiple magnetometers with different radii are fabricated and characterized. By utilizing a microdisk with a radius of 355 μm and a thickness of 1 μm, along with a FeGaB film with a radius of 330 μm and a thickness of 1.3 μm, we have achieved a remarkable peak sensitivity of 1.68 pT Hz−1/2 at 9.52 MHz. This represents a significant improvement of over two orders of magnitude compared with previous studies employing sputtered Terfenol-D film. Notably, the magnetometer operates without a bias magnetic field, thanks to the remarkable soft magnetic properties of the FeGaB film. Furthermore, as a proof of concept, we have demonstrated the real-time measurement of a pulsed magnetic field simulating the corona current in a high-voltage transmission line using our developed magnetometer. These high-sensitivity magnetometers hold great potential for various applications, such as magnetic induction tomography and corona current monitoring.

Faridah Abu Bakar, Nur Syahidatul Insyirah Mohd Foad

Kevin Z. Derby, Kian Milani, Solvay Blomquist et al.

Extreme wavefront correction is required for coronagraphs on future space telescopes to reach 1e-8 or better starlight suppression for the direct imaging and characterization of exoplanets in reflected light. Thus, a suite of wavefront sensors working in tandem with active and adaptive optics are used to achieve stable, nanometer-level wavefront control over long observations. In order to verify wavefront control systems comprehensive and accurate integrated models are needed. These should account for any sources of on-orbit error that may degrade performance past the limit imposed by photon noise. An integrated model of wavefront sensing and control for a space-based coronagraph was created using geometrical raytracing and physical optics propagation methods. Our model concept consists of an active telescope front end in addition to a charge-6 vector vortex coronagraph instrument. The telescope uses phase retrieval to guide primary mirror bending modes and secondary mirror position to control the wavefront error within tens of nanometers. The telescope model is dependent on raytracing to simulate these active optics corrections for compensating the wavefront errors caused by misalignments and thermal gradients in optical components. Entering the coronagraph, a self-coherent camera is used for focal plane wavefront sensing and digging the dark hole. We utilize physical optics propagation to model the coronagraph's sensitivity to mid and high-order wavefront errors caused by optical surface errors and pointing jitter. We use our integrated models to quantify expected starlight suppression versus wavefront sensor signal-to-noise ratio.

Zhifei Hu, Xiangchao Zhang, Wei Lang et al.

With the fast development in the fields of photovoltaics and integrated circuits, the measurement of surface topographies and micro-scaled defects has attracted intensive interests. However, existing measurement methods are time-consuming and unsuitable for in-situ detection. Therefore, a fast topographic measurement method is developed based on the deflectometric microscope system. Microscopic deflectometry is an attractive tool due to its high sensibility to surface slopes and large dynamic range of measurement. For the quantitative reconstruction of surface topographies from slopes, an integration method is developed based on the minimum spanning tree, and the integration path is designed based on a sparse representation and a curl map. The robustness and accuracy of the integration method are validated by numerical simulation and experiments. This method can achieve a high measurement accuracy with a high lateral resolution and a depth of field of 90 μm, hereby improving the manufacturing efficiency and quality of opto-electronics functional devices.

Serguei Smirnov, Aleksandra Przewłoka, Aleksandra Krajewska et al.

Materials with tunable dielectric properties are highly relevant for terahertz (THz) applications. Herein, the tuning of the dielectric response of single‐walled carbon nanotube layers by light illumination is studied for applications to THz phase shifters. The dependence of the length of individual nanotubes on the THz photoconductivity of the network is experimentally investigated in the frequency range of 0.2–1 THz by time‐domain spectroscopy (TDS). The effective conductivity of the networks is described by a theoretical model that fits the measured dielectric function. Terahertz phase shifters are realized with the carbon nanotube layers as the optically tunable element deposited on the wall of rectangular dielectric waveguides. The phase of the electromagnetic wave propagating in the waveguide is shown to be tunable by illuminating the nanotubes. A linear phase shift with the frequency is measured between 75 and 500 GHz with a low change in amplitude due to the illumination.

Anton Losev, Vladimir Zavodilenko, Andrey Koziy et al.

In this paper, we investigateda self-developed sine wave gated single-photon detector (SPD) for 1550 nm wavelength primary for quantum key distribution (QKD) usage. We studied the influence of DC bias voltage and AC gate amplitude on the SPD’s functional parameters and presented a simple and effective algorithm for its optimization. Such optimization showed practical benefits while SPD was set up on the QKD device. We admitted that the dark count rate decreases with an increase in gating voltage with fixed photon detection efficiency. We observed the charge persistence effect in sine-gated SPDs, which previously had been observed only at square-pulses gated SPDs, and showed that this effect is limiting for infinity increasing gate amplitude.

Brenden A. Magill, Kai Wang, Stephen McGill et al.

Traditional organic–inorganic halide perovskites (OIHPs), in which perovskites layers are separated by an organic spacer material, have been mainly explored for photovoltaics devices, but they also offer promises for nonlinear optics and quantum light applications. These attributes include (a) high quantum efficiency, (b) large binding energy of excitons in low-dimensional structures, (c) polarons of long coherence times at room temperature, and (d) a large spin–orbit coupling. OIHP systems can be engineered to have photoluminescence (PL) emissions from UV to IR regions, in addition to power conversion efficiencies, in excess of 24%. This class of materials offers broad tunability of its properties, through controlling the number of atomic layers in the quantum well, tuning the organic spacer thickness, or even engineering the composition with exotic dopants. In this work, we present PL and time-resolved PL measurements of quasi-2D BA2PbI4 and provide new insights on the temperature dependence of their excitonic dynamics and fine structures of their PL emissions. We observed long lifetimes, which can result from the formation of large polarons, screening the Coulomb interactions of the charge carriers and reducing the scattering of the carriers with charge defects.