Visualizing rapid biological dynamics like neuronal signaling and microvascular flow is crucial yet challenging due to photon noise and motion artifacts. Here we present a deep learning framework for enhancing the spatiotemporal relations of optical microscopy data. Our approach leverages correlations of mirrored perspectives from conjugated scan paths, training a model to suppress noise and motion blur by restoring degraded spatial features. Quantitative validation on vibrational calcium imaging validates significant gains in spatiotemporal correlation (2.2×), signal-to-noise ratio (9–12 dB), structural similarity (6.6×), and motion tolerance compared to raw data. We further apply the framework to diverse in vivo experiments from mouse cerebral hemodynamics to zebrafish cardiac dynamics. This approach enables the clear visualization of the rapid nutrient flow (30 mm/s) in microcirculation and the systolic and diastolic processes of heartbeat (2.7 cycle/s), as well as cellular and vascular structure in deep cortex. Unlike techniques relying on temporal correlations, learning inherent spatial priors avoids motion-induced artifacts. This self-supervised strategy flexibly enhances live microscopy under photon-limited and motion-prone regimes.

Metamaterials and metasurfaces of artificial micro-/nano- structures functioning from microwave, terahertz, to infrared regime have enabled numerous applications from bioimaging, cancer detection and immunoassay to on-body health monitoring systems in the past few decades. Recently, the trend of turning metasurface devices flexible and stretchable has arisen in that the flexibility and stretchability not only makes the device more biocompatible and wearable, but also provides unique control and manipulation of the structural and geometrical reconfiguration of the metasurface in a creative manner, resulting in an extraordinary tunability for biomedical sensing and detection purposes. In this Review, we summarize recent advances in the design and fabrication techniques of stretchable reconfigurable metasurfaces and their applications to date thereof, and put forward a perspective for future development of stretchable reconfigurable metamaterials and metasurfaces.

There has been a long fundamental pursuit to enhance and levitate the Raman scattering signal intensity of molecule by a huge number of ~ 14–15 orders of magnitude, to the level comparable with the molecule fluorescence intensity and truly entering the regime of single-molecule Raman spectroscopy. In this work we report unambiguous observation of single-molecule Raman spectroscopy via synergic action of electromagnetic and chemical enhancement for rhodamine B (RhB) molecule absorbed within the plasmonic nanogap formed by gold nanoparticle sitting on the two-dimensional (2D) monolayer WS2 and 2 nm SiO2 coated gold thin film. Raman spectroscopy down to an extremely dilute value of 10–18 mol/L can still be clearly visible, and the statistical enhancement factor could reach 16 orders of magnitude compared with the reference detection sample of silicon plate. The electromagnetic enhancement comes from local surface plasmon resonance induced at the nanogap, which could reach ~ 10–11 orders of magnitude, while the chemical enhancement comes from monolayer WS2 2D material, which could reach 4–5 orders of magnitudes. This synergic route of Raman enhancement devices could open up a new frontier of single molecule science, allowing detection, identification, and monitor of single molecules and their spatial–temporal evolution under various internal and external stimuli.

Detection noise significantly degrades the quality of structured illumination microscopy (SIM) images, especially under low-light conditions. Although supervised learning based denoising methods have shown prominent advances in eliminating the noise-induced artifacts, the requirement of a large amount of high-quality training data severely limits their applications. Here we developed a pixel-realignment-based self-supervised denoising framework for SIM (PRS-SIM) that trains an SIM image denoiser with only noisy data and substantially removes the reconstruction artifacts. We demonstrated that PRS-SIM generates artifact-free images with 20-fold less fluorescence than ordinary imaging conditions while achieving comparable super-resolution capability to the ground truth (GT). Moreover, we developed an easy-to-use plugin that enables both training and implementation of PRS-SIM for multimodal SIM platforms including 2D/3D and linear/nonlinear SIM. With PRS-SIM, we achieved long-term super-resolution live-cell imaging of various vulnerable bioprocesses, revealing the clustered distribution of Clathrin-coated pits and detailed interaction dynamics of multiple organelles and the cytoskeleton.

The vacuum-ultraviolet (VUV, 10–200 nm) imaging photodetector (PD) based on the wide bandgap semiconductor (WBGS) can realize a more detailed observation of solar storms than the silicon ones. Here, an 8 × 8 VUV PD array based on the semiconductor AlN with an ultra-wide bandgap is presented, exhibiting the shortest cutoff wavelength (203 nm) reported so far. The PD array with a Pt/AlN/SiC/Ti/Au photovoltaic structure shows an excellent selective response to VUV light, an extremely low dark current density of 2.85 × 10–11 A·cm-2@ -2 V, a responsivity of 0.054 A·W-1@ 0 V and an ultra-short rise time of 13 ns. Also, the clear boundaries and an obvious contrast between light and dark of the VUV image displayed in the imaging measurement indicate the good imaging ability of this PD array, which can be used for the imaging application with high signal-to-noise ratio and high response speed. These results provide rich experience for the development of VUV imaging PDs based on WBGSs both in their fabrication and the practical applications in VUV detection.

Aqueous zinc-ion batteries provide a most promising alternative to the existing lithium-ion batteries due to their high theoretical capacity, intrinsic safety, and low cost. However, commercializing aqueous zinc-ion batteries suffer from dendritic growth and side reactions on the surface of metallic zinc, resulting in poor reversibility. To overcome this critical challenge, here, we report a one-step ultrafast laser processing method for fabricating three-dimensional micro-/nanostructures on zinc anodes to optimize zinc nucleation and deposition processes. It is demonstrated that the three-dimensional micro-/nanostructure with increased specific surface area significantly reduces nucleation overpotential, as well as preferentially absorbs zinc ions to prevent dendritic protuberances and corrosion. As a result, the presence of three-dimensional micro-/nanostructures on the zinc metal delivers stable zinc plating/stripping beyond 2500 h (2 mA cm-2/1 mAh cm-2) in symmetric cells, a high Coulombic efficiency (99.71%) in half cells, and moreover an improved capacity retention (71.8%) is also observed in full cells. Equally intriguingly, the pouch cell with three-dimensional micro-/nanostructures can operate across various bending states without severely compromising performance. This work provides an effective strategy to construct ultrafine and high-precision three-dimensional micro-/nanostructures achieving high-performance zinc metal anodes and is expected to be of immediate benefit to other metal-based electrodes.

Optical imaging techniques provide low-cost, non-radiative images with high spatiotemporal resolution, making them advantageous for long-term dynamic observation of blood perfusion in stroke research and other brain studies compared to non-optical methods. However, high-resolution imaging in optical microscopy fundamentally requires a tight optical focus, and thus a limited depth of field (DOF). Consequently, large-scale, non-stitched, high-resolution images of curved surfaces, like brains, are difficult to acquire without z-axis scanning. To overcome this limitation, we developed a needle-shaped beam optical coherence tomography angiography (NB-OCTA) system, and for the first time, achieved a volumetric resolution of less than 8 μm in a non-stitched volume space of 6.4 mm × 4 mm × 620 μm in vivo. This system captures the distribution of blood vessels at 3.4-times larger depths than normal OCTA equipped with a Gaussian beam (GB-OCTA). We then employed NB-OCTA to perform long-term observation of cortical blood perfusion after stroke in vivo, and quantitatively analyzed the vessel area density (VAD) and the diameters of representative vessels in different regions over 10 days, revealing different spatiotemporal dynamics in the acute, sub-acute and chronic phase of post-ischemic revascularization. Benefiting from our NB-OCTA, we revealed that the recovery process is not only the result of spontaneous reperfusion, but also the formation of new vessels. This study provides visual and mechanistic insights into strokes and helps to deepen our understanding of the spontaneous response of brain after stroke.

Optical encryption strategies utilizing fully coherent light have been widely explored but often face challenges such as speckle noise and beam instabilities. In this work, we introduce a novel protocol for multi-channel optical information encoding and encryption using vectorial spatial coherence engineering of a partially coherent light beam. By characterizing the beam’s spatial coherence structure with a $$2 \times 2$$ coherence matrix, we demonstrate independent control over the three components of the coherence Stokes vector. This allows for three-channel optical information encoding and encryption, with applications in color image representation. Unlike existing methods based on fully coherent light modulations, our approach utilizes a two-point dependent coherence Stokes vector, proving resilient to random noise in experimental scenarios. Our findings provide a robust foundation for higher-dimensional optical encoding and encryption, addressing limitations associated with partially coherent light in complex environments.

Measurements and imaging of the mechanical response of biological cells are critical for understanding the mechanisms of many diseases, and for fundamental studies of energy, signal and force transduction. The recent emergence of Brillouin microscopy as a powerful non-contact, label-free way to non-invasively and non-destructively assess local viscoelastic properties provides an opportunity to expand the scope of biomechanical research to the sub-cellular level. Brillouin spectroscopy has recently been validated through static measurements of cell viscoelastic properties, however, fast (sub-second) measurements of sub-cellular cytomechanical changes have yet to be reported. In this report, we utilize a custom multimodal spectroscopy system to monitor for the very first time the rapid viscoelastic response of cells and subcellular structures to a short-duration electrical impulse. The cytomechanical response of three subcellular structures - cytoplasm, nucleoplasm, and nucleoli - were monitored, showing distinct mechanical changes despite an identical stimulus. Through this pioneering transformative study, we demonstrate the capability of Brillouin spectroscopy to measure rapid, real-time biomechanical changes within distinct subcellular compartments. Our results support the promising future of Brillouin spectroscopy within the broad scope of cellular biomechanics.

The molecular fingerprint sensing technology based on metasurface has unique attraction in the biomedical field. However, in the terahertz (THz) band, existing metasurface designs based on multi-pixel or angle multiplexing usually require more analyte amount or possess a narrower tuning bandwidth. Here, we propose a novel single-pixel graphene metasurface. Based on the synchronous voltage tuning, this metasurface enables ultra-wideband ( $$\sim$$ 1.5 THz) fingerprint enhancement sensing of trace analytes, including chiral optical isomers, with a limit of detection (LoD) ≤ 0.64 μg/mm2. The enhancement of the fingerprint signal ( $$\sim$$ 17.4 dB) originates from the electromagnetically induced transparency (EIT) effect excited by the metasurface, and the ideal overlap between the light field constrained by single-layer graphene (SLG) and ultra-thin analyte. Meanwhile, due to the unique nonlinear enhancement mechanism in graphene tuning, the absorption envelope distortion is inevitable. To solve this problem, a universal fingerprint spectrum inversion model is developed for the first time, and the restoration of standard fingerprints reaches Rmax2 ≥ 0.99. In addition, the asynchronous voltage tuning of the metasurface provides an opportunity for realizing the dynamic reconfiguration of EIT resonance and the slow light modulation in the broadband range. This work builds a bridge for ultra-wideband THz fingerprint sensing of trace analytes, and has potential applications in active spatial light modulators, slow light devices and dynamic imaging equipments.

Propagating waves and surface waves are two distinct types of light-transporting modes, the free control of which are both highly desired in integration photonics. However, previously realized devices are bulky in sizes, inefficient, and/or can only achieve one type of light-manipulation functionality with a single device. Here, we propose a generic approach to design bi-channel meta-devices, constructed by carefully selected meta-atoms possessing reflection phases of both structural-resonance and geometric origins, which can exhibit two distinct light-manipulation functionalities in near-field (NF) and far-field (FF) channels, respectively. After characterizing the scattering properties of basic meta-atoms and briefly stating the theoretical strategy, we design/fabricate three different meta-devices and experimentally characterize their bi-channel wave-control functionalities in the telecom regime. Our experiments show that the first two devices can multiplex the generations of NF and FF optical vortices with different topological charges, while the third one exhibits anomalous surface plasmon polariton focusing in the NF and hologram formation in the FF simultaneously. Our results expand the wave-control functionalities of metasurfaces to all wave-transporting channels, which may inspire many exciting applications in integration optics.

Fluorescence polarization microscopy is widely used in biology for molecular orientation properties. However, due to the limited temporal resolution of single-molecule orientation localization microscopy and the limited orientation dimension of polarization modulation techniques, achieving simultaneous high temporal-spatial resolution mapping of the three-dimensional (3D) orientation of fluorescent dipoles remains an outstanding problem. Here, we present a super-resolution 3D orientation mapping (3DOM) microscope that resolves 3D orientation by extracting phase information of the six polarization modulation components in reciprocal space. 3DOM achieves an azimuthal precision of 2° and a polar precision of 3° with spatial resolution of up to 128 nm in the experiments. We validate that 3DOM not only reveals the heterogeneity of the milk fat globule membrane, but also elucidates the 3D structure of biological filaments, including the 3D spatial conformation of λ-DNA and the structural disorder of actin filaments. Furthermore, 3DOM images the dipole dynamics of microtubules labeled with green fluorescent protein in live U2OS cells, reporting dynamic 3D orientation variations. Given its easy integration into existing wide-field microscopes, we expect the 3DOM microscope to provide a multi-view versatile strategy for investigating molecular structure and dynamics in biological macromolecules across multiple spatial and temporal scales.

Optical encryption plays an increasingly important role in the field of information security owing to its parallel processing capability and low power consumption. Employing the ultrathin metasurfaces in optical encryption has promoted the miniaturization and multifunctionality of encryption systems. Nevertheless, with the few number of degrees of freedom (DoFs) multiplexed by single metasurface, both key space and encoding space are limited. To address this issue, we propose a high-security and large-capacity optical encryption scheme based on perfect high-dimensional Poincaré beams with expanded DoFs. By cascading two arrayed metasurfaces, more beam properties can be independently engineered, which gives rise to the extensively expanded key and encoding spaces. Our work provides a promising strategy for optical encryption with high security level and large information capacity and might facilitate the applications of Poincaré beams in optical communications and quantum information.

Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency. Compact, integrated optical switches are attractive thanks to their scalability, readiness for mass production, and robustness against mechanical disturbances. The basic unit relies mostly on a microring resonator or a Mach–Zehnder interferometer for binary “bar” and “cross” switching. Such single-mode structures are often wavelength / polarization dependent, sensitive to phase errors and loss-prone. Furthermore, when they are cascaded to a network, the number of control units grows quickly with the port count, causing high complexity in electronic wiring and drive circuit integration. Herein, we propose a new switching method by thermo-optic waveguide lens. Essentially, this multimode waveguide forms a square law medium by a pair of heater electrodes and focuses light within a chip by robust 1 × 1 imaging. A 1 × 24 basic switch is demonstrated with 32 electrodes and only two are biased at a time for a chosen output. By two-level cascading, the switch expands to 576 ports and only four electrodes are needed for one path. The chips are fabricated on wafer scale in a low-budget laboratory without resorting to foundries. Yet, the performance goes beyond state of the art for low insertion loss, low wavelength dependence and low polarization dependence. This work provides an original, alternative, and practical route to construct large-scale optical switches, enabling broad applications in telecom, datacom and photonic computing.

Extreme ultraviolet (EUV) light is difficult to focus due to strong absorption of most materials. Photon sieves (PS), rather than Fresnel zone plates (FZP), can focus EUV to smaller spot and suppress the higher orders of secondary maxima by several orders of magnitude. The number of pinholes used in PS is far more than that of transparent rings used in FZP, providing a great flexibility to manipulate structured focusing in EUV. In this work we investigate the Fermat-spiral PS to produce focused vortices with different topological charges. Experiment at the wavelength of 46.9 nm is carried out and multi-planar coherent diffractive imaging is used to retrieve the phase map of the focused EUV vortices. These results show the enormous potential of PS for manipulating EUV light. This study not only provides a compact, affordable substitute to focusing vortices where transmissive optics materials are unavailable, but also provides a route of converting various complex light manipulation ranging from visible light to EUV and soft x-ray.

Since the concept of adaptive optics(AO) was proposed in 1953, AO has become an indispensable technology for large aperture ground-based optical telescopes aimed at high resolution observations. This paper provides a comprehensive review of AO progress for large aperture astronomical optical telescopes including both night-time and day-time solar optical telescopes. The recent AO technological advances, such as Laser Guide Star, Deformable Secondary Mirror, Extreme AO, and Multi-Conjugate AO are focused.

Wavefront control is the fundamental requirement in optical informatics. Planar optics have drawn intensive attention due to the merits of compactness and light weight. However, it remains a challenge to freely manipulate the dispersion, hindering practical applications, especially in imaging. Here, we propose the concept of frequency-synthesized phase engineering to solve this problem. A phasefront-frequency matrix is properly designed to encode different spatial phases to separate frequencies, thus makes arbitrary dispersion tailoring and even frequency-separated functionalization possible. The periodically rotated director endows cholesteric liquid crystal with a spin and frequency selective reflection. Moreover, via presetting the local initial orientation of liquid crystal, geometric phase is encoded to the reflected light. We verify the proposed strategy by cascading the chiral anisotropic optical media of specifically designed helical pitches and initial director orientations. By this means, planar lenses with RGB achromatic, enhanced chromatic aberration and color routing properties are demonstrated. Inch-sized and high-efficient lenses are fabricated with low crosstalk among colors. It releases the freedom of dispersion control of planar optics, and even enables frequency decoupled phase modulations. This work brings new insights to functional planar optics and may upgrade the performance of existing optical apparatuses.

Lensless fiber endomicroscopy, an emergent paradigm shift for minimally-invasive microscopic optical imaging and targeted light delivery, holds transformative potential, especially in biomedicine. Leveraging holographic detection and physical or computational wavefront correction, it enables three-dimensional imaging in an unprecedentedly small footprint, which is crucial for various applications such as brain surgery. This perspective reviews the recent breakthroughs, highlighting potential emerging applications, and pinpointing gaps between innovation and real-world applications. As the research in this realm accelerates, the novel breakthroughs and existing frontiers highlighted in this perspective can be used as guidelines for researchers joining this exciting domain.

Holographic display offers the capability to generate high-quality images with a wide color gamut since it is laser-driven. However, many existing holographic display techniques fail to fully exploit this potential, primarily due to the system’s imperfections. Such flaws often result in inaccurate color representation, and there is a lack of an efficient way to address this color accuracy issue. In this study, we develop a color-aware hologram optimization approach for color-accurate holographic displays. Our approach integrates both laser and camera into the hologram optimization loop, enabling dynamic optimization of the laser’s output color and the acquisition of physically captured feedback. Moreover, we improve the efficiency of the color-aware optimization process for holographic video displays. We introduce a cascade optimization strategy, which leverages the redundant neighbor hologram information to accelerate the iterative process. We evaluate our method through both simulation and optical experiments, demonstrating the superiority in terms of image quality, color accuracy, and hologram optimization speed compared to previous algorithms. Our approach verifies a promising way to realize a high-fidelity image in the holographic display, which provides a new direction toward the practical holographic display.

Three-dimensional (3D) panoramic vision system plays a fundamental role in the biological perception of external information, and naturally becomes a key system for embodied intelligence to interact with the outside world. A binocular vision system with rotating eyeball has long baseline, large volume and weak sensitivity to motion. A compound eye system has small volume, high sensitivity to motion but poor precision. Here, a planar compound eye microsystem for high precision 3D perception is proposed by combining semiconductor manufacturing process and biological compound eye structure. Using a semiconductor planar image sensor as the sensing unit, a space-coded planar sub-eye array is designed and its sub field of view (FOV) is dynamically mapped to the image sensor. It solves the problem that a traditional vision system cannot simultaneously accommodate wide FOV with long focal length and high sensitivity to motion with high resolution. The parallax among different sub-eyes enables the system to accurately perceive and dynamically track the 3D position of the target in the range of 10 m and within the FOV of 120 ° in a single compound eye. This system is of great significance in the fields of intelligent robot and intelligent perception.

Surface plasmon resonance (SPR) sensors are based on photon-excited surface charge density oscillations confined at metal-dielectric interfaces, which makes them highly sensitive to biological or chemical molecular bindings to functional metallic surfaces. Metal nanostructures further concentrate surface plasmons into a smaller area than the diffraction limit, thus strengthening photon-sample interactions. However, plasmonic sensors based on intensity detection provide limited resolution with long acquisition time owing to their high vulnerability to environmental and instrumental noises. Here, we demonstrate fast and precise detection of noble gas dynamics at single molecular resolution via frequency-comb-referenced plasmonic phase spectroscopy. The photon-sample interaction was enhanced by a factor of 3,852 than the physical sample thickness owing to plasmon resonance and thermophoresis-assisted optical confinement effects. By utilizing a sharp plasmonic phase slope and a high heterodyne information carrier, a small atomic-density modulation was clearly resolved at 5 Hz with a resolution of 0.06 Ar atoms per nano-hole (in 10–11 RIU) in Allan deviation at 0.2 s; a faster motion up to 200 Hz was clearly resolved. This fast and precise sensing technique can enable the in-depth analysis of fast fluid dynamics with the utmost resolution for a better understanding of biomedical, chemical, and physical events and interactions.

The issue of brightness in strong ambient light conditions is one of the critical obstacles restricting the application of augmented reality (AR) and mixed reality (MR). Gallium nitride (GaN)-based micro-LEDs, renowned for their exceptional brightness and stability, are considered the foremost contenders for AR applications. Nevertheless, conventional heteroepitaxial growth micro-LED devices confront formidable challenges, including substantial wavelength shifts and efficiency droop. In this paper, we firstly demonstrated the high-quality homoepitaxial GaN-on-GaN micro-LEDs micro-display, and thoroughly analyzed the possible benefits for free-standing GaN substrate from the material-level characterization to device optoelectronic properties and micro-display application compared with sapphire substrate. The GaN-on-GaN structure exhibits a superior crystal quality with ultra-low threading dislocation densities (TDDs) of ~ 105 cm-2, which is three orders of magnitude lower than that of GaN-on-Sapphire. Through an in-depth size-dependent optoelectronic analysis of blue/green emission GaN-on-GaN/ Sapphire micro-LEDs from 100 × 100 shrink to 3 × 3 μm2, real that a lower forward voltage and series resistance, a consistent emission wavelength (1.21 nm for blue and 4.79 nm for green @ 500 A/cm2), coupled with a notable reduction in efficiency droop ratios (15.6% for blue and 28.5% for green @ 500 A/cm2) and expanded color gamut (103.57% over Rec. 2020) within GaN-on-GaN 10 μm micro-LEDs. Last but not least, the GaN-on-GaN micro-display with 3000 pixels per inch (PPI) showcased enhanced display uniformity and higher luminance in comparison to its GaN-on-Sapphire counterpart, demonstrating significant potentials for high-brightness AR/MR applications under strong ambient light.

Refractive index (RI) sensors play an important role in various applications including biomedical analysis and food processing industries. However, developing RI sensors with both high resolution and wide linear range remains a great challenge due to the tradeoff between quality (Q) factor and free spectral range (FSR) of resonance mode. Herein, the optical steelyard principle is presented to address this challenge by synergizing resonances from the Fabry–Perot (FP) cavity and metasurface, integrated in a hybrid configuration form on the end facet of optical fibers. Specifically, the FP resonance acting like the scale beam, offers high resolution while the plasmonic resonance acting like the weight, provides a wide linear range. Featuring asymmetric Fano spectrum due to modal coupling between these two resonances, a high Q value (~ 3829 in liquid) and a sensing resolution (figure of merit) of 2664 RIU-1 are experimentally demonstrated. Meanwhile, a wide RI sensing range (1.330–1.430 in the simulation and 1.3403–1.3757 in the experiment) is realized, corresponding to a spectral shift across several FSRs (four and two FSRs in the simulation and experiment, respectively). The proposed steelyard RI sensing strategy is promising in versatile monitoring applications, e.g., water salinity/turbidity and biomedical reaction process, and could be extended to other types of sensors calling for both high resolution and wide linear range.

Recent advances in imaging sensors and digital light projection technology have facilitated rapid progress in 3D optical sensing, enabling 3D surfaces of complex-shaped objects to be captured with high resolution and accuracy. Nevertheless, due to the inherent synchronous pattern projection and image acquisition mechanism, the temporal resolution of conventional structured light or fringe projection profilometry (FPP) based 3D imaging methods is still limited to the native detector frame rates. In this work, we demonstrate a new 3D imaging method, termed deep-learning-enabled multiplexed FPP (DLMFPP), that allows to achieve high-resolution and high-speed 3D imaging at near-one-order of magnitude-higher 3D frame rate with conventional low-speed cameras. By encoding temporal information in one multiplexed fringe pattern, DLMFPP harnesses deep neural networks embedded with Fourier transform, phase-shifting and ensemble learning to decompose the pattern and analyze separate fringes, furnishing a high signal-to-noise ratio and a ready-to-implement solution over conventional computational imaging techniques. We demonstrate this method by measuring different types of transient scenes, including rotating fan blades and bullet fired from a toy gun, at kHz using cameras of around 100 Hz. Experiential results establish that DLMFPP allows slow-scan cameras with their known advantages in terms of cost and spatial resolution to be used for high-speed 3D imaging tasks.

Period-doubling bifurcation, as an intermediate state between order and chaos, is ubiquitous in all disciplines of nonlinear science. However, previous experimental observations of period doubling in ultrafast fiber lasers are mainly restricted to self-sustained steady state, controllable manipulation and dynamic switching between period doubling and other intriguing dynamical states are still largely unexplored. Here, we propose to expand the vision of dissipative soliton periodic doubling, which we illustrate experimentally by reporting original spontaneous, collisional, and controllable spectral period doubling in a polarization-maintaining ultrafast fiber laser. Specifically, the spontaneous period doubling can be observed in both single- and double-pulses. The mechanism of the switchable state and periodic doubling was revealed by numerical simulation. Moreover, state transformation of individual solitons can be resolved during the collision of triple solitons involving stationary, oscillating, and period doubling. Further, controllable deterministic switching between period doubling and other dynamical states, as well as exemplifying the application of period-doubling-based digital encoding, is achieved under programmable pump modulation. Our results open a new window for unveiling complex Hopf bifurcation in dissipative systems and bring useful insights into nonlinear science and applications.

The field of high-bandwidth holography has been extensively studied over the past decade. Orbital angular momentum (OAM) holography, which utilizes vortex beams with theoretically unbounded OAM modes as information carriers, showcases the large capacitance of hologram storage. However, OAM holography has been limited to a single wavelength, restricting its potential for full-color holography and displays. In this study, we propose wavelength and OAM multiplexed holography that utilizes the multiple dimensions of light—wavelength and OAM—to provide a multi-color platform that expands the information capacity of holographic storage devices. The proposed wavelength-OAM multiplexed holography is physically realized by a metasurface, the state-of-the-art optical element consisting of an array of artificially engineered nanostructures. Hydrogenated silicon meta-atoms, the constituents of the metasurface, are engineered to possess wavelength selectivity by tailoring the dispersion of polarization conversion. These meta-atoms are used to encode the calculated OAM-preserved phase maps based on our design. The sampling grid of the phase map is rotated by 45°, which effectively suppress higher-order diffraction, providing a great strategy for achieving large field-of-view (FOV) holography. We successfully demonstrate six holographic images that are selectively reconstructed under the illumination of light with specific wavelengths (λ = 450, 635 nm) and topological charges (l = -2, 0, 2), without high-order diffraction. Our work suggests that ultrathin meta-holograms can potentially realize ultrahigh-bandwidth full-color holography and holographic video displays with large FOV.

The programmable photonic integrated mesh is arising as a powerful tool to deal with crosstalk in the multimode optical communication link.

Single-molecule localization microscopy (SMLM) surpasses the diffraction limit by randomly switching fluorophores between fluorescent and dark states, precisely pinpointing the resulted isolated emission patterns, thereby reconstructing the super-resolution images based on the accumulated locations of thousands to millions of single molecules. This technique achieves a ten-fold improvement in resolution, unveiling the intricate details of molecular activities and structures in cells and tissues. Multicolor SMLM extends this capability by imaging distinct protein species labeled with various fluorescent probes, providing insights into structural intricacies and spatial relationships among different targets. This review explores recent advancements in multicolor SMLM, evaluates the strengths and limitations of each variant, and discusses the future prospects.

Over the past few decades, metasurfaces have revolutionized conventional bulky optics by providing an effective approach to manipulate optical waves at the subwavelength scale. This advancement holds great potential for compact, multifunctional, and reconfigurable optical devices. Notably, metasurfaces constructed with anisotropic nanostructures have exhibited remarkable capability in manipulating the polarization state of optical waves. Furthermore, they can be employed to achieve independent control of the amplitude and phase of optical waves in different polarization channels. This capability has garnered significant attention from the photonics community due to its unprecedented potential for polarization-selective and -multiplexed optical wave manipulation, offering versatile applications in optical imaging, communication, and detection. This paper reviews the design principles, representative works, and recent advancements in anisotropic nanostructures for optical polarization manipulation, detection, as well as polarization-selective and -multiplexed optical wave manipulation. Personal insights into further developments in this research area are provided.

Photonic integrated circuits (PICs) represent a promising technology for the much-needed medical devices of today. Their primary advantage lies in their ability to integrate multiple functions onto a single chip, thereby reducing the complexity, size, maintenance requirements, and costs. When applied to optical coherence tomography (OCT), the leading tool for state-of-the-art ophthalmic diagnosis, PICs have the potential to increase accessibility, especially in scenarios, where size, weight, or costs are limiting factors. In this paper, we present a PIC-based CMOS-compatible spectrometer for spectral domain OCT with an unprecedented level of integration. To achieve this, we co-integrated a 512-channel arrayed waveguide grating with electronics. We successfully addressed the challenge of establishing a connection from the optical waveguides to the photodiodes monolithically co-integrated on the chip with minimal losses achieving a coupling efficiency of 70%. With this fully integrated PIC-based spectrometer interfaced to a spectral domain OCT system, we reached a sensitivity of 92dB at an imaging speed of 55kHz, with a 6dB signal roll-off occurring at 2mm. We successfully applied this innovative technology to obtain 3D in vivo tomograms of zebrafish larvae and human skin. This ground-breaking fully integrated spectrometer represents a significant step towards a miniaturised, cost-effective, and maintenance-free OCT system.

Owing to the ability to parallel manipulate micro-objects, dynamic holographic optical tweezers (HOTs) are widely used for assembly and patterning of particles or cells. However, for simultaneous control of large-scale targets, potential collisions could lead to defects in the formed patterns. Herein we introduce the artificial potential field (APF) to develop dynamic HOTs that enable collision-avoidance micro-manipulation. By eliminating collision risks among particles, this method can maximize the degree of parallelism in multi-particle transport, and it permits the implementation of the Hungarian algorithm for matching the particles with their target sites in a minimal pathway. In proof-of-concept experiments, we employ APF-empowered dynamic HOTs to achieve direct assembly of a defect-free 8 × 8 array of microbeads, which starts from random initial positions. We further demonstrate successive flexible transformations of a 7 × 7 microbead array, by regulating its tilt angle and inter-particle spacing distances with a minimalist path. We anticipate that the proposed method will become a versatile tool to open up new possibilities for parallel optical micromanipulation tasks in a variety of fields.

In recent years, quantum nanophotonics has forged a rich nexus of nanotechnology with photonic quantum information processing, offering remarkable prospects for advancing quantum technologies beyond their current technical limits in terms of physical compactness, energy efficiency, operation speed, temperature robustness and scalability. In this perspective, we highlight a number of recent studies that reveal the especially compelling potential of nanoplasmonic cavity quantum electrodynamics for driving quantum technologies down to nanoscale spatial and ultrafast temporal regimes, whilst elevating them to ambient temperatures. Our perspective encompasses innovative proposals for quantum plasmonic biosensing, driving ultrafast single-photon emission and achieving near-field multipartite entanglement in the strong coupling regime, with a notable emphasis on the use of industry-grade devices. We conclude with an outlook emphasizing how the bespoke characteristics and functionalities of plasmonic devices are shaping contemporary research directives in ultrafast and room-temperature quantum nanotechnologies.

Computer holography is a prominent technique for reconstructing customized three-dimensional (3D) diffraction fields. However, the quality of optical reconstruction remains a fundamental challenge in 3D computer holography, especially for the 3D diffraction fields with physically continuous and extensive depth range. Here, we propose a 3D computer-generated hologram (CGH) optimization framework with phase space tailoring. Based on phase space analysis of the space and frequency properties in both lateral and axial directions, the intensity of the 3D diffraction field is adequately sampled across a large depth range. This sampling ensures the reconstructed intensity distribution to be comprehensively constrained with physical consistency. A physics-informed loss function is constructed based on the phase space tailoring to optimize the CGH with suppression of vortex stagnation. Numerical and optical experiments demonstrate the proposed method significantly enhances the 3D optical reconstructions with suppressed speckle noise across a continuous and extensive depth range.

Cancer-associated adipocytes (CAAs) have emerged as pivotal players in various cancers, particularly in such as breast cancer, significantly influencing their progression and therapy resistance. Understanding the adipocytes/cancer cells crosstalk is crucial for effective treatment strategies. Raman spectroscopy, a label-free optical technique, offers potential for characterizing biological samples by providing chemical-specific information. In this study, we used Raman spectroscopy and Trajectory Inference methods, specifically the Partition-based graph abstraction algorithm, to investigate the interactions between 3T3-L1 differentiated adipocytes and MDA-MB-231 breast cancer cells in a 2D co-culture model. We demonstrate the existence of subpopulations of adipocytes and the molecular changes associated with CAAs phenotype. This work contributes to understanding the role of CAAs in breast cancer progression and may guide the development of targeted therapies disrupting this interaction.

Pulsed polarized vortex beams, a special form of structured light, are generated by tailoring the light beam spatiotemporally and witness the growing application demands in nonlinear optics such as ultrafast laser processing and surface plasma excitation. However, existing techniques for generating polarized vortex beams suffer from either low compactness due to the use of bulky components or limited controlment of pulse performance. Here, an all-fiber technique combining plasmonic metafibers with mode conversion method is harnessed to generate high-performance pulsed polarized vortex beams. Plasmonic metafibers are utilized as saturable absorbers to produce Q-switched pulses with micro-second duration, while the offset splicing method is employed to partially convert the fundamental transverse mode (LP $$~~{01}$$ ) to higher-order mode (LP $$~~{11}$$ ). Eventually, a polarized vortex beams laser is achieved at the telecom band with a repetition frequency of 116.0 kHz. The impact of geometrical parameters including period of metafibers and offset of splicing on the spatiotemporal properties of pulsed polarized vortex beams is systematically investigated. Our findings could pave the way for design, control and generation of all-fiber pulsed polarized vortex beams, and also offer insights into the development of other types of structured laser sources.

Single-pixel detectors are popular devices in optical sciences because of their fast temporal response, high sensitivity, and low cost. However, when being used for imaging, they face a fundamental challenge in acquiring high-dimensional information of an optical field because they are essentially zero-dimensional sensors and measure only the light intensity. To address this problem, we developed a cascaded compressed-sensing single-pixel camera, which decomposes the measurement into multiple stages, sequentially reducing the dimensionality of the data from a high-dimensional space to zero dimension. This measurement scheme allows us to exploit the compressibility of a natural scene in multiple domains, leading to highly efficient data acquisition. We demonstrated our method in several demanding applications, including enabling tunable single-pixel full-waveform hyperspectral light detection and ranging (LIDAR) for the first time.

Information security plays an important role in every aspect of life to protect data from stealing and deciphering. However, most of the previously reported works were based on pure algorithm layer or pure physical layer encryptions, which have certain limitations in security. In this paper, a nondeterministic message encryption communication scheme is proposed based on a spin-space-frequency multiplexing metasurface (SSFMM), which integrates both algorithmic and physical layer encryptions, and can also produce multiple different ciphertexts for the same message to prevent the message from being cracked through frequency analysis, thus greatly enhancing the security of the information. To be specific, an SSFMM is first designed as a physical-layer meta-key, which can generate eight independent dot matrix holograms with different spin, space, and frequency characteristics. The target message is then encrypted based on these dot matrix holograms combined with algorithmic operations, and the encrypted message is converted into a quick response (QR) code for easy sending to the target users. Once the target user gets that QR code, he/she can scan it to obtain the encryption information, and then recover the target message according to the pre-agreed encryption protocol combined with the eight dot matrix holograms of SSFMM. Finally, the feasibility of the proposed encryption scheme was experimentally validated at the microwave frequency band.

The classical properties of thermal light fields were instrumental in shaping our early understanding of light. Before the invention of the laser, thermal light was used to investigate the wave-particle duality of light. The subsequent formulation of the quantum theory of electromagnetic radiation later confirmed the classical nature of thermal light fields. Here, we fragment a pseudothermal field into its multiparticle constituents to demonstrate that it can host multiphoton dynamics mediated by either classical or quantum properties of coherence. This is shown in a forty-particle system through a process of scattering mediated by twisted paths endowed with orbital angular momentum. This platform enables accurate projections of the scattered pseudothermal system into isolated multiphoton subsystems governed by quantum dynamics. Interestingly, the isolated multiphoton subsystems exhibiting quantum coherence produce interference patterns previously attributed to entangled optical systems. As such, our work unveils novel mechanisms to isolate quantum systems from classical fields. This possibility opens new paradigms in quantum physics with enormous implications for the development of robust quantum technologies.

Holography is an essential technique of generating three-dimensional images. Recently, quantum holography with undetected photons (QHUP) has emerged as a groundbreaking method capable of capturing complex amplitude images. Despite its potential, the practical application of QHUP has been limited by susceptibility to phase disturbances, low interference visibility, and limited spatial resolution. Deep learning, recognized for its ability in processing complex data, holds significant promise in addressing these challenges. In this report, we present an ample advancement in QHUP achieved by harnessing the power of deep learning to extract images from single-shot holograms, resulting in vastly reduced noise and distortion, alongside a notable enhancement in spatial resolution. The proposed and demonstrated deep learning QHUP (DL-QHUP) methodology offers a transformative solution by delivering high-speed imaging, improved spatial resolution, and superior noise resilience, making it suitable for diverse applications across an array of research fields stretching from biomedical imaging to remote sensing. DL-QHUP signifies a crucial leap forward in the realm of holography, demonstrating its immense potential to revolutionize imaging capabilities and pave the way for advancements in various scientific disciplines. The integration of DL-QHUP promises to unlock new possibilities in imaging applications, transcending existing limitations and offering unparalleled performance in challenging environments.

Soliton molecules (SMs) play a crucial role in nonlinear optical systems, enriching our understanding of nonlinear science through the study of their interaction dynamics. While passively mode-locked fiber lasers offer an efficient platform for generating diverse types of SMs, the complex internal dynamics of the laser often pose challenges in achieving predetermined temporal separations between SMs. Here, we implement a delayed optical feedback technique within a femtosecond optical parametric oscillator, enabling the generation of SMs with precise and controllable temporal separations. A theoretical model, which models the intracavity iterations of the signal with a simplified Ikeda map, is proposed to study the impact of parametric gain, intracavity feedback delay, and cavity length on the internal separations of the SMs. Our experimental results confirm that adjusting the cavity length allows for producing desired temporal separations within SMs. To reveal the evolution dynamics of the SMs, we further develop a rigorous numerical model using the carrier-resolved Forward Maxwell Equation, which is capable of modeling ultra-broadband complex dynamics based on a single equation without relying on the slowly-varying envelope approximation. The numerical model unveils the rich formation dynamics of the SMs at various separations, which confirms the critical role of the gain window provided by the pump. This work opens up new opportunities for the on-demand generation of SMs and provides valuable insights into the complex dynamics in femtosecond optical parametric oscillator systems with optical delayed feedback.

Nonlinear Raman-Nath diffraction (NRND) is a unique diffraction pattern formed when a high-intensity laser interacts with a nonlinear microstructure bulky medium relying only on the transverse phase matching condition. Here, we report on the first experimental observation of NRND in a submicron-thick periodically poled lithium niobate thin film (PPLNTF) by geometric reflection pumped via a near-infrared femtosecond pulse laser. We further observe the evolution of the diffracted signals after broadening of the pump laser via a fused silica plate. We systematically analyze the spectral properties of multi-order second harmonic generation (SHG) diffracted signals exhibiting asymmetric distributions and explicitly clarify their phase matching conditions, simultaneously considering the impacts of the incident pump wavelength, the sample poling period, and the incident angle on the properties of the angular distribution diffracted beams. The realization of NRND phenomena with appreciable on-chip efficiency at a submicron interaction length is mainly attributed to the significant contribution of domain walls to enhance the nonlinear effects along with the modulation of second-order nonlinear susceptibilities $${\chi }^{(2)}$$ . This NRND scheme provides a high-resolution, non-destructive on-chip microstructure diagnostic method, and even has the potential to develop novel on-chip integrated optoelectronic devices for applications such as precision metrology, biosensing, and spectral analysis.

Micro/nanorobots have shown great potential to execute different tasks in microenvironments due to their small size, high controllability and environmental adaptability. However, it is still challenging to precisely control the deformation and navigation of soft micro/nanorobots to better adapt to unstructured and complex surroundings. Here, we report a photonic nanojet (PNJ)-regulated soft microalga robot (saBOT) based on Euglena gracilis with controlled deformation and precise navigation capability. The deformability of the saBOT was precisely controlled by the highly focused light energy from a microlens-based PNJ bound to a tapered optical fiber probe (TFP), which can precisely stimulate the channelrhodopsin-2 (ChR2) in the photoreceptor of the microalga. This saBOT can be further precisely navigated toward different positions in complex and unstructured microenvironments by combining the deformability with the phototaxis ability of the microalga via the flexible manipulation of TFP. Notably, due to the ability of controllable deformation and precision navigation, the saBOT can travel across cell clusters for precision drug delivery toward a target cell. This PNJ-regulated saBOT holds great promise in executing different biomedical tasks in complex and unstructured microenvironments that cannot be reached by conventional tools and rigid microrobots.