Optical Review最新文献

We present a rapid wavefront sensor based on machine learning and using a line-scan camera. The object light wave propagates through a scattering medium. In our method, the scattered light wave undergoes a series of preconditioning steps. The resultant light wave, in which only the wavefront aberration component is emphasized and the reference object light wave is removed, is captured as one-dimensional data using line focusing optics. The captured data are trained by a convolutional neural network, and the trained network can estimate the Zernike coefficients without iterative calculations. The proposed method achieves significantly faster measurement compared to a two-dimensional sensor. The proposed method was experimentally demonstrated, as a proof of concept, using a line-scan camera and a preconditioning method that we designed.

Head-mounted displays (HMDs) for augmented reality (AR) require optical systems that deliver high luminance, high optical see-through performance, and high image resolution. Conventional two-directional pupil expansion using beam splitter array (BSA) waveguides often suffers from low light coupling efficiency and degraded image quality due to narrow coupling mirrors and wavefront disturbances caused by exposed mirror edges along the total internal reflection surface. We propose a novel HMD optical system that combines a pupil expansion (PE) prism with a one-directional BSA waveguide. The PE prism features an enlarged coupling surface, efficiently capturing light from the light engine. Importantly, the PE prism is designed to avoid exposed mirror edges in the optical path, thereby eliminating wavefront disturbances and enabling high-resolution virtual image projection. Within the PE prism, multiple ray paths are generated through complex reflections and transmissions via overlapping multi-mirrors. This multi-path propagation not only expands the eye-box orthogonally to the BSA waveguide, but also ensures uniform output luminance. A prototype HMD implementing the proposed method achieves high luminance (over 5000 cd/m²), high image resolution (MTF > 58% at 10 cycles/degree), high optical see-through transparency (over 94%), and luminance uniformity (over 53%). These results demonstrate significant improvements over conventional BSA waveguide approaches.

The exact analytical solution of the electric field of the Airy beam with a polarization in the x-direction is derived by the vector angular spectrum theory. And then, the evanescent interference of two symmetrically offset evanescent Airy beams is investigated by the angular spectrum theory in detail. Two separated Airy beams at the initial position will overlap and interfere due to the lateral self-acceleration. The y-axis interference field shows a superior stability and a slower decay compared to the x-axis. The interference optical field forms a spindle-shaped central optical field along the y-axis, and the intensity rapidly decays along the x-axis, and a small-scale scattered optical field is formed in the low-intensity regions on both sides. The result is useful to elucidating the formation mechanism and theoretical properties of the interference phenomenon of Airy beams.

This study presents a theoretical and numerical investigation of local field enhancement and optical bistability in ZnSe-based core–shell nanocomposites, providing insights for photonic applications. The structures consist of a ZnSe dielectric core and a metallic shell of either silver ((textrm{Ag})) or gold ((textrm{Au})), embedded in oxide matrices ((textrm{SiO}_2), (textrm{ZnO}), or (textrm{HFO}_2)) with varying permittivities. Using the quasi-static approximation and the Lorentz–Drude model, we analyze how variations in the core radius (keeping the outer radius fixed) influence spectral response and local field enhancement. Results show that smaller cores (thicker shells) yield stronger local field enhancement factors ((textrm{LFEF})) due to increased plasmonic confinement. Ag shells produce sharper, more intense resonances than Au, attributed to lower damping and superior plasmonic performance. The dielectric environment also plays a key role: low-permittivity matrices like (textrm{SiO}_2) support higher field localization, while high-permittivity ones such as (textrm{HFO}_2) weaken confinement and blue-shift the resonances. Nonlinear analysis reveals that thicker shells and lower matrix permittivity enhance bistability and reduce switching thresholds, particularly in Ag-based systems. These findings highlight the critical influence of geometry and material choice on both linear and nonlinear optical responses. The results offer practical guidance for engineering core–shell nanocomposites tailored for applications in photonic devices, optical sensors, and all-optical switching.

In this study, we investigate the time-fractional perturbed nonlinear Schrödinger equation in the context of optical fibers using the newly extended mapping scheme. As a result, many types of traveling wave solutions are obtained, including novel solitary wave solutions, triangular, hyperbolic, and periodic wave solutions expressed in terms of Jacobi elliptic functions. Solutions are obtained as well in the limiting cases for (ell) approach 0 or 1. By assigning specific values to the free parameters, the physical significance of the 2D and 3D geometric shapes of the derived solutions is discussed, and the corresponding physical variations are illustrated. This work demonstrates the applicability of the proposed method to a broader class of nonlinear evolution equations in physics and engineering.

Recent advances in lensless imaging reconstruction have primarily relied on supervised neural models trained using target images captured by lensed cameras via a beam splitter. However, we argue that using reference images from a different optical system introduces bias into the reconstruction process. To mitigate this issue, we propose a self-supervised approach that leverages data-fidelity guidance, similar to deep image prior, to train neural models for single-iteration lensless reconstruction. Through simulations and prototype camera experiments, we demonstrate that combining simple convex optimization methods with a denoising UNet improves perceptual quality (LPIPS), accelerates inference compared to traditional optimization techniques, and reduces potential unwanted biases in the reconstruction network.

Detectors based on cross delay-line (XDL) anodes with charge induction are widely applicable in space astronomical telescopes, deep space exploration, and fluorescence lifetime measurements. In this article, a three-dimensional structure XDL anode based on Printed Circuit Board (PCB) technology is proposed, which can conveniently realize high-resolution detection with a simple process and low cost. We theoretically studied the charge induction principle and established a model of the XDL anode through the finite element method. The model allows us to determine anode parameters, such as anode strip width, inter-strip distance, and substrate thickness, to optimize the output signal on the XDL anode, thereby indirectly affecting the resolution of the detector. Based on the experimental platform, we systematically characterized the key performance parameters of the detector. We conclude that the spatial resolution of the detector is better than 50 (upmu)m and the non-linearity is less than 5(%).

Owing to the rapid growth of digital information, demand for archival storage with high data transfer rate, large capacity, longevity, low power consumption, and low running cost has surged. Although holographic data storage (HDS) is considered as a promising candidate for next-generation archival storage due to its potential in these areas, it has not been released commercially due to difficulties in stable recording and reproduction across the whole recording area or multibook area. In this study, we proposed a robust multibook recording technique based on signal beam phase optimization using the Gerchberg–Saxton (GS) algorithm. We optimized the target distribution of the signal beam amplitude at the Fourier plane for the GS algorithm, considering the hologram recording and reproduction characteristics, such as DC suppression, inter-book-interference (IBI) reduction, and the signal-to-noise ratio (SNR). Optical simulation of multibook recording and reproduction shows that IBI can be properly reduced, and sufficient SNR can be retained even if 13.6% book misalignments occur during recording. In addition, combining the proposed technique with an accurate book alignment method could increase the HDS capacity by 33.9%.

When a hydrophone with a vibrating membrane is placed in water, the ultrasonic waves to be detected diffract and reflect. Therefore, conventional hydrophones cannot accurately measure the sound field distribution. Another noncontact method for measuring the sound field distribution is the Schlieren method. However, this method requires meticulous optical axis adjustment using a Schlieren lens and a knife edge, and this method is not versatile. Therefore, a laser hydrophone, which uses the self-coupling effect of a semiconductor laser to detect ultrasonic waves without contact with the sound field, is developed, and the sound field is investigated. The optical system of the laser hydrophone is composed of only a few components. In addition, because ultrasonic waves can be detected using only a small amount of light, no optical axis adjustment is necessary. The frequency response of the laser hydrophone is flat. The upper limit of the detectable frequency is determined by the relationship between the large diameter of the laser beam and the frequency of the ultrasonic waves. The measured sound pressure distribution of the laser hydrophone qualitatively agreed with that of the simulation.

Given that silicon-on-insulator (SOI) has a high refractive index contrast and intrinsic birefringence, photonics devices based on SOI are typically polarization-sensitive. To address this issue, a novel broadband mid-infrared polarization rotator (PR) based on cascaded stepped waveguides was put forward. It can achieve polarization conversion between the fundamental TM₀ and TE₀ modes through mode hybridization formed in asymmetric waveguides. The finite-difference time-domain (FDTD) method was employed to explore its polarization rotation characteristics and optimize the device structure. Simulation results demonstrate that at the central wavelength of 2.53 µm, the maximum polarization extinction ratio (PER) can attain 40.02 dB, the polarization conversion efficiency (PCE) exceeds 99.8%, and the insertion loss (IL) is as low as 0.12 dB. Moreover, the operating bandwidth is expanded to 490 nm (spanning from 2.28 to 2.77 µm). Meanwhile, the device length is merely 16.4 μm. Furthermore, tolerance analysis indicates that the device has good manufacturing tolerance. Owing to its high PER, large bandwidth, and small footprint, the proposed PR has significant application potential in mid-infrared photonic integrated circuits (PICs).