Light Field Research Articles

Filterless vector light field photodetector based on photonic-electronic co-designed non-Hermitian silicon nanostructures

Recent advances in near-field interference detection, inspired by the non-Hermitian coupling-induced directional sensing of Ormia ochracea, have demonstrated the potential of paired semiconductor nanowires for compact light field detection without optical filters. However, practical implementation faces significant challenges including limited active area, architectural scaling constraints, and incomplete characterization of angular and polarization information. Here, we demonstrate a filterless vector light field photodetector, leveraging the angle- and polarization-sensitive near-field interference of non-Hermitian semiconductor nanostructures. Our design unit comprises four devices, each containing identical silicon nanowires but varying in orientation and electric connection configuration, of which the four-dimensional photoconductive output can be uniquely mapped to key vector light field parameters: intensity, polar angle, azimuth angle, and the linear polarization difference (Stokes parameter, S1). Optimization of the geometry and doping concentration of these optoelectronic nanostructures yields a theoretical polar angle detectivity of 4 × 10−5 °/Hz0.5. This work establishes a paradigm for multi-output photodetectors with full-rank response matrices for multi-dimensional light field characterization, paving the way for integrated vector light field sensing systems.

Large screen size transparent display using spectrum expanded light field holograms

Holographic displays have the potential to reconstruct natural light field information, making them highly promising for applications in augmented reality (AR), head-up displays (HUD), and new types of transparent three-dimensional (3D) displays. However, current spatial light modulators (SLMs) are constrained by pixel size and resolution, limiting display size. Additionally, existing holographic displays have narrow viewing angles due to device diffraction limits, algorithms, and optical configurations. To overcome these obstacles, we propose a transparent large-size light-field holographic display system. This system utilizes a spectrum-expanded light-field holography algorithm that decomposes the light field in the spectrum domain according to each viewing angle. The spectrum is expanded by a factor of 3. The proposed algorithm widens the viewing angle of the holographic display and utilizes the full spectrum of the display device to support smooth motion parallax as well as the natural depth of field of the light field. Furthermore, we further enlarge the display size by introducing waveguides, and optimize the far-field display performance of the waveguide. The display size is enlarged to 100 mm compared to the general method. The extended spectrum enhances the diffraction angle on the waveguide’s grating, resolving content discontinuity in far-field views. The proposed method allows for a more vivid perception of light fields with motion parallax and depth effects on a large transparent screen.

Real-time deconvolution of light fields through pixel selection in the point-spread-function and direct inversion of the image formation process

This paper explores the optimization of light field deconvolution, a key process in image processing that reconstructs a 3D object space or a 2D refocus plane from a light field. Despite the critical role of deconvolution in light field technology, existing methods are often slow, computationally intensive, and unsuitable for real-time processing. Existing algorithms, such as the Richardson-Lucy approach, while groundbreaking, still suffer performance limitations due to their iterative nature and high computational costs. Central to our approach is the strategic selection of influential pixels within the point-spread-function, reducing redundant computations by focusing only on pixels contributing to a significant portion of the point-spread-function’s total intensity. In addition, we explore the potential to directly invert the image formation model, bypass iterative computations, and further accelerate the deconvolution process. Our findings reveal notable improvements in computational efficiency, with some of our methods achieving real-time performance. The reconstruction quality, measured using metrics such as the mean squared error, remained comparable to existing approaches, indicating a favorable balance between speed and reconstruction quality.

Controlled propagation and particle manipulation of off-axis-rotating elliptical Gaussian beams in strong nonlocal media

Abstract Off-axis-rotating elliptical Gaussian beams(OareGB) oblique incidence in strong nonlocal medium exhibit novel propagation properties.The analytical expressions of semi-axial beamwidths, and center-of-mass trajectory equations for transmitting off-axis-rotating elliptical Gaussian beams in strong nonlocal media are obtained using the ABCD transfer matrix method. The study revealed that the trajectory of the mass’s center in the cross-section can be controlled by changing the sizes of the OareGB parameters c, d, ζ, and f. The gradient force of the light field causes the spot region to form a spatial potential well in the media, and this spatial potential well can effectively capture nanoparticles. The particles captured by the light field can move along with the beam, realizing the effective manipulation of the particle trajectory. These laws may be applied to modulating the propagation path of light beams and optical tweezer technology.

Ferrofluid‐Assisted Dynamic Metasurface 3D Holography Endowed With Rapid, Linear, and High‐Contrast Color Modulation

AbstractMetasurface holography offers a highly promising approach for naked‐eye, full‐color, 3D displays. However, the natural static structure and material of the metasurface limit its ability to dynamically regulate the light field, posing a challenge for achieving photorealistic 3D holography. Here, a ferrofluid‐assisted dynamic metasurface is first demonstrated, conducting a 3D holography endowed with rapid, linear, and high‐contrast color modulation. The ferrofluid has nano‐structural control properties (flow behavior of nanoparticles and emulsion) that enable dynamic manipulation of the extinction (absorption and scattering) intensity in micron region across a broadband spectrum range (400–850 nm). By integrating the ferrofluid with a broadband metasurface, a novel dynamic meta‐hologram is created, which can not only regulate both amplitude and phase of the light field under a single wavelength laser but also in situ linearly changing the color of holographic images under multi‐wavelength lasers. This method provides a new perspective for implementing dynamic metasurface 3D holography capable of continuous color response.

4D Bioprinting: Keeping the Technology Alive

Abstract4D bioprinting is a groundbreaking technology with potential to revolutionize healthcare. It is based on additive manufacturing technologies, which are used to fabricate dynamic prosthetics and devices from biologically compatible smart materials that respond to stimuli. The ultimate end of 4D bioprinting is the creation of an artificial organ that perfectly mimics the functional movements of a native organ and is fully integrated within the human body. In this perspective, two phases are identified toward this end. The first is minimally invasive surgery (MIS) using shape memory composites stimulated by near‐infrared (NIR) light and/or magnetic fields. The second is dynamic tissue engineering (DTE) with activation by biological stimuli.

3D reconstruction of highly reflective surface based on multi-view fusion and point cloud fitting with structured light field

3D reconstruction of highly reflective surface based on multi-view fusion and point cloud fitting with structured light field

Phase-dependent Hanbury-Brown and Twiss effect for the complete measurement of the complex coherence function

Hanbury-Brown and Twiss (HBT) effect is the foundation for stellar intensity interferometry. However, it is a phase insensitive two-photon interference effect. Here we extend the HBT interferometer by mixing intensity-matched reference fields with the input fields before intensity correlation measurement. With the freely available coherent state serving as the reference field, we experimentally demonstrate the phase sensitive two-photon interference effect when the input fields are thermal fields in either continuous wave or non-stationary pulsed wave and measure the complete complex second-order coherence function of the input fields without bringing them together from separate locations. Moreover, we discuss how to improve the signal level by using the more realistic continuous wave broadband anti-bunched light fields as the reference field. Our investigations pave the way for developing new technology of remote sensing and interferometric imaging with applications in long baseline high-resolution astronomy.

Manipulating continuous optical spectra in the wave vector domain by metalens.

Complete 2π cycling of a phase around a phase singularity leads to a rapid phase variation in the nearby zones and forms a sharp local k-vector peak. In this paper, the intensity distribution in the spatial domain is transformed into a k-vector distribution in the wave vector domain, and we prove that the local k-vector peak is generated at the point of minimum light field intensity. The local k-vector peak is sharper when the minimum point is closer to the phase singularity. The k-vector peak can be manipulated by controlling the minimum optical field intensity. A metalens is designed to generate sharp k-vector peaks for continuous wavelengths and linearly shift the positions of these peaks with the incident wavelength. This method transforms full-band continuous optical spectra from the spatial domain to the wave vector domain. The spectral resolutions over the wavelength range from 800 nm to 810 nm are less than 0.82 nm, and the optimal spectral resolution reaches 0.027 nm. This approach can be used in metasurface spectroscopy, providing what we believe to be a new way to improve spectral resolution.

Full-reference light field image quality assessment based on multi-feature interactive fusion network

Full-reference light field image quality assessment based on multi-feature interactive fusion network

Interstitial Oxygen-Driven Far-Red/Near-Infrared Emission and Efficiency Enhancement via Heterovalent Cation Substitution in Ca3WO6 Phosphors.

In this work, Ca3WO6 (CWO) phosphors were successfully synthesized using a high-temperature solid-state method, exhibiting an anomalous far-red/near-infrared (FR-NIR) emission centered at 685 nm. The origin of this FR-NIR emission is confirmed through Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), density functional theory (DFT) calculations, and heterovalent cationic substitution (Y3+/Na+ → Ca2+). These analyses indicate that interstitial oxygen (Oi) defects within the lattice are primarily responsible for the FR-NIR emission. The heterovalent substitution of Y3+ for Ca2+ increases the concentration of Oi, significantly enhancing the FR-NIR emission intensity. This results in an increase in the internal quantum efficiency (IQE) increasing from 12.8 to 90.9%, realizing an efficient FR-NIR emission from self-activated phosphors. Furthermore, CWO phosphors demonstrate a unique dual-band emission characterized by a blue emission at 435 nm and an FR-NIR emission at 685 nm. This dual-band emission endows CWO phosphors with multifunctional applications in plant growth lighting, nondestructive testing, and night vision fields.

Smartphone based non invasive real time white blood cell counter leveraging blue light and static magnetic field

White blood cells (WBCs), also known as leukocytes, are one of the most significant parts of the immune system. They generate antibodies, protect the body from illnesses, and heal wounds. Accurate estimation of WBCs is key for diagnosing cancer, infections, leukemia, lymphoma, and other diseases. However, the widely used Complete Blood Count (CBC) test presents challenges, including prick anxiety, discomfort, and logistical inconvenience to patients. This study introduces a ubiquous White Blood Cell counting system, UbiWhite, a novel smartphone-based, non-invasive system for real-time WBC counting from fingertip videos. Our system uses optical and magnetic techniques to provide accurate WBC counts without blood extraction. An initial experimentation was carried out on 20 adult participants to verify the system’s effectiveness compared to standard CBC tests (IRB #4051). The developed algorithms exhibit 1.04 and 1.23 RMSE, respectively. Our innovation provides an easy, affordable, and instantaneous solution for monitoring WBCs in various healthcare settings, including homes and critical care units. Additionally, it serves as a beacon of hope for low- and middle-income nations, where access to and affordability of traditional lab tests are limited.

Computationally Efficient Light Field Video Compression Using 5-D Approximate DCT

Five-dimensional (5-D) light field videos (LFVs) capture spatial, angular, and temporal variations in light rays emanating from scenes. This leads to a significantly large amount of data compared to conventional three-dimensional videos, which capture only spatial and temporal variations in light rays. In this paper, we propose an LFV compression technique using low-complexity 5-D approximate discrete cosine transform (ADCT). To further reduce the computational complexity, our algorithm exploits the partial separability of LFV representations. It applies two-dimensional (2-D) ADCT for sub-aperture images of LFV frames with intra-view and inter-view configurations. Furthermore, we apply one-dimensional ADCT to the temporal dimension. We evaluate the performance of the proposed LFV compression technique using several 5-D ADCT algorithms, and the exact 5-D discrete cosine transform (DCT). The experimental results obtained with LFVs confirm that the proposed LFV compression technique provides a more than 250 times reduction in the data size with near-lossless fidelity with a peak-signal-to-noise ratio greater than 40 dB and structural similarity index greater than 0.9. Furthermore, compared to the exact DCT, our algorithms requires approximately 10 times less computational complexity.

Far-field Characterization Method for 3D Light Field Displays Evaluation

Far-field Characterization Method for 3D Light Field Displays Evaluation

Rapid Focused Spot Scanning Imaging Using Multimode Fiber with a Convolutional Neural Network-Based Phase Modulation

In this paper, we present a rapid beam-focusing method for multimode fiber (MMF) that integrates a Convolutional Neural Network (CNN) with a Spatial Light Modulator (SLM). This approach efficiently focuses light fields by training neural networks to approximate the transmission matrix of the optical system, eliminating the need for iterative calculations. Experimental results indicate that this method can generate focused spots within 200 ms, representing a significant improvement over traditional methods. Additionally, the feasibility of point-scanning imaging was verified using the USAF-1951 test target with a resolution greater than 7.81 μm. This advance is expected to improve the speed and accuracy of endoscopic imaging and other real-time imaging applications, potentially leading to more effective diagnostic tools and imaging technologies in medical and industrial settings.

Combined effect of light and magnetic field on recombinant protein production driven by photosystem II-related gene promoters in the cyanobacterium Synechococcus elongatus PCC 7942

Combined effect of light and magnetic field on recombinant protein production driven by photosystem II-related gene promoters in the cyanobacterium Synechococcus elongatus PCC 7942

Nonlinear Optics in Two-Dimensional Magnetic Materials: Advancements and Opportunities.

Nonlinear optics, a critical branch of modern optics, presents unique potential in the study of two-dimensional (2D) magnetic materials. These materials, characterized by their ultra-thin geometry, long-range magnetic order, and diverse electronic properties, serve as an exceptional platform for exploring nonlinear optical effects. Under strong light fields, 2D magnetic materials exhibit significant nonlinear optical responses, enabling advancements in novel optoelectronic devices. This paper outlines the principles of nonlinear optics and the magnetic structures of 2D materials, reviews recent progress in nonlinear optical studies, including magnetic structure detection and nonlinear optical imaging, and highlights their role in probing magnetic properties by combining second harmonic generation (SHG) and multispectral integration. Finally, we discuss the prospects and challenges for applying nonlinear optics to 2D magnetic materials, emphasizing their potential in next-generation photonic and spintronic devices.

Light Field Modulation Algorithms for Spatial Light Modulators: A Review

The coding method of spatial light modulator is the core key of spatial light field modulation technology, and the needs of the modulation algorithm are different under the specified mode and application requirements. This paper first reviews the progress made in recent years in light field control algorithms for digital micromirror devices (DMDs) and liquid crystal spatial light modulators (LC-SLM). Based on existing algorithms, the impact of optimization methods is analyzed. Then, the application areas of the different algorithms are summarized, and the characteristics of the control algorithms are analyzed. In addition, this review highlights innovative breakthroughs achieved by using various coding schemes and spatial light modulators (SLM) to manipulate the light field. Finally, critical future challenges facing emerging control algorithm technologies are outlined, while prospects for developing SLM control algorithms are proposed.

Intelligent responsive nanogels: New Horizons in cancer therapy.

Biologically engineered nanogels formed through sophisticated intramolecular crosslinking processes represent the forefront of next-generation drug delivery systems. These innovative systems offer many advantages, like adjustable size, satisfactory biocompatibility, and minimal toxicity. Their unique attributes facilitate deep penetration and long-term retention of drugs in tumors, effectively enhancing the anti-tumor effects. Nonetheless, the rapid disintegration of nanogels and the subsequent triggering of drug release at the tumor site pose significant challenges in achieving more effective and precise tumor treatments. Therefore, increasing research has been dedicated to exploring stimulus-responsive nanogels for enhancing tumor therapy. This review aims to encapsulate the research advancements in emerging stimulus-responsive antitumor nanogels. Firstly, a detailed exposition is provided on various endogenous stimulus-responsive nanogels, encompassing factors such as pH, hypoxia, enzymes, reactive oxygen species (ROS), and glutathione (GSH). Secondly, various nanogels triggered by exogenous stimuli such as light, ultrasound, temperature, and magnetic fields are elaborately presented. Furthermore, nanogels with multifaceted stimulus-responsive properties are also skillfully designed. Finally, the future directions, application prospects, and challenges of intelligent responsive nanogels in cancer treatment are highlighted.

Liquid Crystal Microlens Arrays Based on Aluminum-doped Zinc Oxide Oriented Microstructure Facilitate Light Field Image Resolution Enhancement

Liquid Crystal Microlens Arrays Based on Aluminum-doped Zinc Oxide Oriented Microstructure Facilitate Light Field Image Resolution Enhancement