To address the current issues of low reconfigurability, low integration, and high dynamic power consumption in programmable units, this study proposes a novel programmable photonic unit cell, termed MZI-cascaded-ring unit (MCR). The unit functions analogously to an MZI, enabling broadband routing when operating within the free spectral range (FSR) of the embedded resonator, and it transitions into a wavelength-selective mode, leveraging the micro-ring’s resonance to achieve precise amplitude and phase control for narrowband signals while outside the FSR, featuring dual operational regimes. With the implementation of spiral waveguide structures, the design achieves higher integration density and lower dynamic power consumption. Based on the hexagonal mesh extension of such a unit, the programmable photonic processor successfully demonstrates a reconfiguration of large amounts of fundamental functions with tunable performance metrics, including broadband linear operations like optical router and wavelength-selective functionalities like wavelength division multiplexing. This work establishes a new paradigm for programmable photonic integrated circuit design.

The flexibility and active control of terahertz multi-focal focusing is essential for advancing next-generation terahertz communication systems. Here, we present and experimentally demonstrate a voltage-controlled liquid crystal (LC) integrated terahertz multi-focal metalens capable of dynamically reconfiguring focal configurations. Both simulation and experimental results confirm electrically modulated spatial-spin separation and multi-focal focusing within the 0.44–0.55 THz frequency band, exhibiting single-to-quadruple switching for left-handed circularly polarized (LCP) waves and dual-to-single transitions for right-handed circularly polarized (RCP) waves. The LC cascaded metalens achieves a measured full-width-at-half-maximum (FWHM) of <2.35 mm and a peak focusing efficiency of 70.4%. The normalized total output power of single, two, and four focal points exceeds 85.1%, 54.9%, and 59.3%. The combination of spatial-spin separation and reconfigurable focus modes is expected to significantly increase the capacity and energy efficiency of future terahertz communication systems.

Vector vortex beams (VVBs) have garnered significant attention in fields such as photonics, quantum information processing, and optical manipulation due to their unique optical properties. However, traditional metasurface fabrication methods are often complex and costly, limiting their practical application. This study successfully fabricated an all-dielectric aluminum oxide metasurface capable of achieving longitudinal variation using 3D printing technology. Experimental results demonstrate that this metasurface generates longitudinally varying VVBs at 0.1 THz, with detailed characterization of its longitudinal intensity distribution and vector polarization states. The high consistency between experimental and simulation results validates the effectiveness of 3D printing in metasurface fabrication. The proposed metasurface offers promising applications in optical polarization control and communication, providing, to our knowledge, new insights and technical support for related research.

By introducing photonic crystals with Dirac point based on valley edge states, we design heterostructure waveguides on the silicon-on-insulator platform, promising waveguides with different widths to operate in the single-mode state. Benefiting from the unidirectional transmission and backscattering-immunity characteristics enabled by the topological property, there is no scattering loss induced by the mode-mismatch at the transition junction between the waveguides with different widths. Therefore, the valley-locked heterostructure waveguide possesses unique width degrees of freedom. We demonstrate it by designing and fabricating waveguides with expanding, shrinking, and Z-type configurations. Thanks to the free transition between waveguides with different widths, an interesting energy convergency is observed, which is represented from the imaging of the enhanced third-harmonic generation of the silicon slab. Consequently, these heterostructure waveguides can be more flexibly integrated with existing on-chip devices and have the potential for high-capacity energy transmission, energy concentration, and field enhancement.

Silicon carbide (SiC) has great potential for optomechanical applications due to its outstanding optical and mechanical properties. However, challenges associated with SiC nanofabrication have constrained its adoption in optomechanical devices, as embodied by the considerable optical loss or lack of integrated optical access in existing mechanical resonators. In this work, we overcome such challenges and demonstrate a low-loss, ultracompact optomechanical resonator in an integrated 4H-SiC-on-insulator (4H-SiCOI) photonic platform for the first time, to our knowledge. Based on a suspended 4.3-μm-radius microdisk, the SiC optomechanical resonator features low optical loss (<1 dB/cm), a high mechanical frequency fm of 0.95×109 Hz, a mechanical quality factor Qm of 1.92×104, and a footprint of <1×10-5 mm2. The corresponding fm·Qm product is estimated to be 1.82×1013 Hz, which is among the highest reported values of optomechanical cavities tested in ambient environment at room temperature. In addition, the strong optomechanical coupling in the SiC microdisk enables coherent regenerative optomechanical oscillations at a threshold optical dropped power of 14 μW, which also supports efficient harmonic generation at increased power levels. With such competitive performance, we envision a range of chip-scale optomechanical applications to be enabled by the low-loss 4H-SiCOI platform.

Neuromorphic photonic systems offer significant advantages for parallel, high-speed, and low-power computing, among which spiking neural networks emerge as a powerful bio-inspired alternative. This study demonstrates, to our knowledge, a novel approach to all-optical spiking processing and reservoir computing using passive silicon microring resonators (MRRs). A key innovation is the demonstration of deterministic optical spiking and spectro-temporal coincidence detection without the need for pump-and-probe methods, simplifying the architecture and improving efficiency. By leveraging injection of excitatory optical signals at negative wavelength detuning relative to the MRR’s cold resonances, the system delivers prompt and high-contrast optical spiking events, essential for effective chip-integrated photonic spiking neural networks. Building on this, a photonic spiking reservoir computer is implemented using a single silicon MRR. The system encodes input information through a novel spectro-temporal scheme and classifies the Iris-Flower dataset with 92% accuracy. This performance is achieved with just 48 reservoir virtual nodes, averaging only three spikes per flower sample, hence highlighting the system’s efficiency and sparsity. These findings unlock novel neuromorphic photonic frameworks with MRRs, enabling sparse all-optical spiking processing and reservoir computing, particularly promising to be adapted in future coupled MRR structures and with binary output weights for light-enabled edge computing and sensing applications.

Visible light communication plays an essential role in the next-generation 6G network due to its extremely high bandwidth and ultrafast transmission speed. Incorporating position sensing functionality into the communication system is highly desired for achieving target-oriented beamforming and accommodating high-speed data service. However, an efficient solution to integrated sensing and light communication remains challenging. Here, we demonstrate an integrated system that concurrently accomplishes high-precision sensing and high-speed data transmission by spatio-temporal modulation of the illumination and computational reconstruction. We developed a compressive angular projection imaging scheme to achieve rapid three-dimensional localization with high resolution, and a jointly optimized waveform design ensures slight sacrifice in the transmission data rate on the integrated system. We experimentally demonstrated a resolving resolution of 1 mm in lateral and 4 cm in depth within 0.6 m×0.6 m×0.6 m volume over 2 m distance at the sensing speed of 39 Hz in both static and dynamic conditions. This capability enables adaptive beamforming, which significantly enhances the data rate by 184% to permit errorless transmission of high-throughput virtual reality videos. Our work offers a promising route for intelligent wireless light communication systems with spatial perception capability, presenting the possibility of cable-free, immersive virtual reality experiences.

There is growing global interest in establishing free-space optical (FSO) communication links, such as ground-satellite links (GSLs) of at least hundreds of kilometers, intersatellite links of thousands of kilometers, and future deep space links of much greater dimensions. Enabling outdoor wireless FSO communication systems to be utilized during daylight hours can increase their availability in space-air-ground networks; however, this is usually accompanied by incoherent background radiation that impairs the signal-to-noise ratio (SNR) and bit error rate (BER). Therefore, a preliminary review of the background noise is required before constructing ground terminals with a suitable SNR in a harsh environment with high levels of solar noise. Herein, we evaluated the background noise that sunlight provides to ground terminals and quantitatively examined its impact on the SNR, communication performance, and beacon detection accuracy of the developed all-free-space ground terminal. Furthermore, we present the results of a daytime demonstration of a 7-km terrestrial free-space optical communication link by employing our ground terminal that was designed based on these analyses. The results verified that 2.5-Gbps data transmission up to 7 km is feasible, even in expected daytime satellite tracking scenarios with high background noise, by the developed system with spectral and spatial filtering to achieve an acceptable SNR. The background noise results of our research are anticipated to further the research on quantum communication networks, light detection and ranging (LiDAR), and green energy technologies.

Miniaturized spectrometers with high resolving power and cost-effectiveness are desirable but remain an open challenge. In this work, we repurpose a fiber generated by the catastrophic fuse effect and ingeniously harness it for a speckle-based computational spectrometer. Without complex disorder engineering, the axially random micro-cavities in the fused fiber enhance the wavelength sensitivity of multimode interference, enabling a 10 cm fiber to achieve a spectral resolution of 0.1 nm. This performance exhibits sixfold improvement over a common multimode fiber configuration of the same length. Furthermore, we develop a spectral reconstruction method that combines a weighted transmission matrix with automatic differentiation, which reduces the reconstruction error by approximately half and enhances the peak signal-to-noise ratio by 6.12 dB compared to traditional Tikhonov regularization. Spectra spanning a 40 nm range, exhibiting both sparse and dense characteristics, are accurately reconstructed. To the best of our knowledge, this represents the first application of fused fiber in computational spectrometers, demonstrating its potential for a wide range of spectral measurement scenarios.

Free-space strong-field terahertz (THz) pulses, generated via optical rectification of femtosecond lasers in nonlinear crystals, are pivotal in various applications. However, conventional Ti:sapphire lasers struggle to produce high-average-power THz sources due to their limited output power. While kilowatt ytterbium lasers are increasingly adopted, their application in THz generation faces challenges: low optical-to-THz conversion efficiency (attributed to long pulse duration and low energy) and crystal damage under high pumping power. Here, we report a high-average-power strong-field THz source using a lithium niobate crystal pumped by a 1030 nm, 570 fs, 1 mJ, 50 kHz ytterbium femtosecond laser with tilted pulse front pumping (TPFP). By systematically optimizing TPFP implementations and comparing grating- and echelon-type configurations, we achieve a THz source with 64.5 mW average power at 42 W, 50 kHz pumping, and focused peak electric field of 525 kV/cm at 0.83 mJ, 1 kHz operation. Additionally, we observe Zeeman torque signals in cobalt-iron ferromagnetic nanofilms. This high-repetition-rate, high-average-power THz system, combined with its potential capabilities in high signal-to-noise ratio spectroscopy and imaging, promises transformative impacts in quantum matter manipulation, non-destructive testing, and biomedicine.

We present a high-power and broadband terahertz (THz) time-domain spectroscopy setup utilizing the nonlinear organic crystal MNA both as an emitter and a detector. The THz source is based on optical rectification of near-infrared laser pulses at a central wavelength of 1036 nm from a commercial, high-power Yb-based laser system and reaches a high THz average power of 11 mW at a repetition rate of 100 kHz and a broad bandwidth of more than 9 THz without a significant power fall-off in the higher THz frequency components. The conversion efficiency is high (0.13%) in spite of the high excitation average power of 8 W. We validate the high dynamic range and reliability of the source for applications in linear spectroscopy by measuring the broadband THz properties of χ(2) nonlinear crystals up to 8 THz. This new high-repetition-rate source is very promising for ultra-broadband THz spectroscopy at high dynamic range and/or reduced measurement time.

In complex environments, infrared camouflage within the long-wave infrared range is essential for modern defense and surveillance applications, requiring precise control over both radiative and scattering properties of military targets. For practical implementation, developing surfaces that integrate dynamic emissivity control, low specular reflectance, and scalable fabrication processes remains a significant challenge. Here, a novel infrared camouflage device is proposed to simultaneously achieve low specular reflectance (<0.1) and dynamic infrared camouflage. The device seamlessly blends into backgrounds with temperatures ranging from 35°C to 45°C by tuning the emissivity of the device, which is attained by controlling the Ge2Sb2Te5 phase change. In addition, it reflects almost no surrounding thermal signals compared with the conventional low-emissivity smooth surface. The thermal camouflage remains effective and stable across observation angles ranging from 20° to 60°. This work proposes a novel approach to simultaneously reducing specular reflection and dynamic emissivity control, potentially inspiring future research and applications in multispectral camouflage and stealth technology.

Upconversion nanoparticles (UCNPs) have attracted considerable interest due to their large anti-Stokes shift, offering promising applications in lasing. Here, multi-wavelength upconversion whispering gallery mode (WGM) lasing is demonstrated in silica microspheres coated with NaYF4@NaYbF4:1%Tm3+@NaYF4 nanoparticles and coupled with tapered fibers. Under continuous-wave 980 nm pumping, low-threshold lasing is achieved across Tm3+ transitions from near-infrared to visible, with an ultra-low threshold of 0.61 μW for the H43→H36 transition. Additionally, upconversion laser output can also be achieved in Er3+- and Ho3+-activated microspheres. These results establish tapered fiber coupling as a versatile approach for enhancing upconversion microlasers.

Non-Hermitian chiral coalescence associated with polarization in optical scattering systems has been routinely realized and applied. However, the scattering exceptional points (EPs) associated with polarization obtained by modes with broadband response and high dissipation constrain its further application in narrowband optics. Here, as a scheme, distinct from the implementation pathway of traditional EPs, we introduce a quasi-bound state in the continuum based on a quadrupole mode as the response environment for EP generation, achieving an EP with high-quality-factor characteristics on a metasurface. Furthermore, we demonstrate the robustness of EPs as intrinsic features of non-Hermitian systems, independent of specific parameter choices. Finally, we present an example of direct chirality detection and display, showcasing the maximum spin-selective property induced by EPs. Our approach unveils the potential of scattering chiral EPs for applications in narrowband optics.

Optical topological quasiparticles with nontrivial topological textures, such as skyrmions and meron lattices, have attracted considerable attention due to their potential applications in high-dimensional optical data storage and communications. Most previous studies of optical topological quasiparticles have focused on the formation of topological structures in isotropic media, whereas in our work, we perform a comprehensive investigation into the formation, topological stability, and phase transitions of optical meron lattices at the metal/uniaxial crystal interface. Our theoretical studies show that by rotating the optical axis orientation of the uniaxial crystal, meron lattices constructed by electric-field vector undergo phase transitions from a topologically nontrivial to a topologically trivial state, whereas the skyrmion number of the spin meron lattices remains robust against such rotations. The findings offer new insights into the topological stability and phase transitions of topological quasiparticles under light–matter interactions and hold promise for applications in optical data storage, information encryption, and communications.

Nonreciprocal optical devices are key components in photonic integrated circuits for light reflection blocking and routing. Most reported silicon integrated nonreciprocal optical devices to date were unit devices. To allow complex signal routing between multiple ports in photonic networks, multi-port magneto-optical (MO) nonreciprocal photonic devices are desired. In this study, we report experimental demonstration of a silicon integrated 5×5 nonreciprocal optical router based on a magneto-optical phased array. By introducing different nonreciprocal phase shifts to planar photonic waveguides, the device focuses light to different ports for both forward and backward propagation directions. The device shows designable nonreciprocal optical transmission between 5×5 ports, achieving 16 dB isolation ratio and -18 dB crosstalk.

The high degree of freedom of multimechanism metasurfaces has greatly facilitated multifunction or even multiphysics design for practical applications. In this work, to achieve camouflages simultaneously in microwave, infrared, and optical regimes, we propose a multimechanism-empowered metasurface composed of four elemental indium-tin-oxide-based meta-atoms. Each meta-atom can modulate microwaves both in phase and magnitude through polarization conversion and resonance absorption, which can realize radar stealth at 8–14 GHz. The reflective amplitude is less than -10 dB. When the incident angle increases to 60°, the reflective amplitude is still less than -3 dB. The far-field scattering patterns of microwaves are modulated by destructive interferences of reflected waves, which results in diffusion-like scattering due to randomly distributed reflection phases on the metasurface. The superposition of microwave absorption and diffuse reflection enables broadband microwave scattering reduction of the metasurface. Meanwhile, the emissivity of four types of meta-atoms covers from 0.3–0.8 at 3–14 μm due to delicately designed occupation ratios. The infrared radiation of the metasurface exhibits the characteristics of digital camouflage in infrared imaging. To demonstrate this method, prototypes were fabricated and measured. The measured results are consistent with the simulated ones. The angular stability in the microwave range within 0°–60° was also demonstrated. This work presents an approach to achieving multispectrum functions with integrated multimechanisms in a single functional metasurface layer and offers a new methodology for custom-designing infrared performance. Moreover, the simplicity of the structure offers significant cost control and large-scale fabrication advantages.

Developing approaches for precise engineering of the optical response of plasmonic nanocavities at the post-fabrication stage is important for achieving enhanced and tunable light-matter interactions. In this work, we demonstrate selective enhancement/suppression of specific plasmonic modes by embedding nanocube-on-mirror plasmonic nanocavities into a poly(methyl methacrylate) (PMMA) layer with a controllable thickness. With the increase of the PMMA thickness from 0 to approximately 100 nm, the dominating out-of-plane plasmonic modes are significantly suppressed in the scattering spectra, while the in-plane plasmonic modes are greatly enhanced with a factor reaching 102±20. This enhancement is related to the variation of momentum matching between the plasmonic modes and the radiative fields, affecting both mode excitation and emission properties. In addition, the spectral positions of the in-plane and out-of-plane plasmonic modes shift up to 52±5 and 81±2 nm, respectively. These properties are important for matching and enhancing plasmonic and molecular resonances in a variety of applications.

Cholestatic liver diseases (CLD) lead to bile accumulation, hepatobiliary dysfunction, and progressive liver damage. Early, accurate evaluation of cholestasis is essential for improving prognosis. In this study, we developed a cross-scale, noninvasive optical imaging platform designed to evaluate both microstructure and metabolic functions in cases of intrahepatic cholestasis, such as primary biliary cholangitis, as well as extrahepatic cholestasis resulting from bile duct ligation. We employed high-resolution photoacoustic microscopy to assess changes in bile duct permeability, hepatic lobular architecture, and blood oxygen saturation following varying degrees of bile duct injury. Meanwhile, we utilized near-infrared-II fluorescence imaging to track the transport of indocyanine green, thereby mapping the absorption and excretion dynamics throughout the liver. Liver function reserve was monitored in situ using contrast-enhanced photoacoustic computed tomography. The imaging manifestations of microstructural alterations and functional impairments associated with cholestasis were quantitatively characterized, demonstrating a correlation with disease progression and validation of our findings. This platform enables dynamic, high-resolution assessment of small bile duct injury and hepatobiliary dysfunction, offering a promising tool for early diagnosis, monitoring, and therapeutic evaluation of CLD.

Polarization detection is essential for various applications, ranging from biological diagnostics to quantum optics. Although various metasurface-based polarimeters have emerged, these platforms are commonly realized through spatial-division designs, which restrict detection accuracy due to inherent factors such as crosstalk. Here, we propose, to our knowledge, a novel strategy for high-accuracy, broadband full-Stokes polarization detection based on the analysis of a single vector beam, whose polarization profile varies sensitively and exhibits a one-to-one correspondence with the incident polarization. Based on this, the incident polarization is completely encoded into the field profile of the vector beam, which avoids crosstalk in principle, and results in high-accuracy polarization detection without any calibration process. As a proof of concept, a geometric-phase metasurface-based grafted perfect vector vortex beam (GPVVB) generator was designed and fabricated. Experimental results demonstrate that our method achieves polarization detection with an average relative error of 2.25%. Benefiting from the broadband high transmittance exceeding 95% of the metasurface due to the femtosecond laser-induced birefringence process, our method operates across a wavelength range of 450–1100 nm. Furthermore, the detection capability of the vector beam polarization profile was validated using a GPVVB-generating array. These results highlight the potential of our approach for transformative applications in polarization detection, including optical communication and machine vision.

Circular dichroism (CD) spectroscopy, widely used for chiral sensing, has been limited by the detection sensitivity. Enhancing optical chirality in the light fields interacting with chiral molecules is crucial for achieving ultrasensitive chiral detection. Here, we present a new paradigm for ultrasensitive chiral detection by creating accessible chiral hotspots using a toroidal dipole Fabry–Perot bound state in the continuum (TD FP-BIC) metasurface. BIC resonance is achieved by controlling the coupling between the TD resonance and its multilayer reflector-induced perfect mirror image. This method enables unprecedented local maximum and average optical chirality enhancements of up to 6×104-fold and 2×103-fold, respectively, within non-structured regions, resulting in an 866-fold increase in CD signals compared to chiral molecules alone without nanostructures. Our results pave the way for enhanced light–matter interactions and ultrasensitive enantiomeric operation.

Two-dimensional second-order spatial differentiation metasurfaces with different numerical apertures (NAs) were designed by the spatial-frequency Trust-Region algorithm, which can be directly embedded into existing optical imaging systems to efficiently extract edge information of the observed targets. The spatial-frequency Trust-Region algorithm was implemented by integrating the Fourier modal method (FMM) with the Trust-Region algorithm to perform inverse optimization of the metasurface nanostructure. The fabricated metasurface with high-resolution functionality achieved a resolution of 1.2 μm and numerical aperture of 0.87, while the high-contrast one obtained a root-mean-square (RMS) contrast higher than that of the first with a numerical aperture of 0.26. Embedded in an optical microscope, the high-resolution differentiation metasurface, with more high-spatial-frequency components in the transfer function, was utilized to extract fine structures of unstained, even transparent, cell images, providing a new avenue for image segmentation, such as in magnetic resonance imaging. The high-contrast counterpart, due to its high transmission efficiency, was employed to detect edges in dynamic images of paramecia and Brachionus without motion smear, offering potential for application in microsurgical procedures involving real-time image analysis.

Symmetry plays a fundamental role in topological photonic crystals, and topological phase transitions induced by disorder have also been extensively explored in recent years. However, in this work, we find anisotropy can be induced by reducing symmetry in a C2v symmetry triangular photonic crystal. We investigate that anisotropy-induced interfaces profoundly affect edge states and enable the realization of slow light dispersion. Numerical simulations reveal a transition from gapless chiral edge modes to gapped flat band dispersion. Furthermore, we observe higher-order corner states in corner structures constructed by anisotropic interfaces. The corner states can be induced and localized at different lattice positions, thereby realizing multiple types of higher-order topological states. We demonstrate the significance of anisotropic geometry in topological photonics. These findings open new possibilities for steering wave transport in multiple dimensions and offer, to our knowledge, a novel research perspective on the transformation of topological states induced by anisotropic lattices.

Inhomogeneous uniaxial strain-induced lattice deformations result in the Dirac point shift, leading to a strong synthetic pseudomagnetic field. The chiral edge state in the Haldane model and the antichiral edge state in the modified Haldane model can be realized in gyromagnetic photonic crystals, immersed in external real magnetic fields. Here, the interplay of the real- and pseudo-magnetic fields is investigated based on the onsite magnetization modulation and the uniaxial strain within gyromagnetic photonic crystals, thereby resulting in photonic band deformations including the shift of the chiral edge states and the lift of the degenerate antichiral edge states. The experiment is further performed to observe the imbalanced transport of these edge states on two opposite sides. Our findings can help to deeply explore rich and significant physics of synthetic gauge fields, and facilitate designs of photonic functional devices, such as the proposed unidirectional multichannel waveguide.

We demonstrate that a moiré superlattice nanocavity constructed in a photonic crystal slab promises strongly enhanced nonlinear optics, which is beneficial from the high-quality factor and high coupling efficiency of the flat-band mode with zero group velocity. From a silicon moiré superlattice nanocavity integrated with few-layer gallium selenide (GaSe), the second-harmonic generation (SHG) of GaSe is enhanced by over 10,000 times, and the third-harmonic generation (THG) is enhanced by 8500 times. Our results suggest the moiré superlattice nanocavity could be considered as a promising platform for developing high-efficiency nonlinear photonic devices.

The near-eye display feature in emerging spatial computing systems produces a distinctive visual effect of mixing virtual and real worlds. However, its application for all-day wear is greatly limited by the bulky structure, energy expenditure, and continuous battery heating. Here, we propose a lightweight holographic near-eye display system that takes advantage of solar energy for self-charging. To guarantee the collection of solar energy and near-eye display without crosstalk, we implement holographic optical elements (HOEs) to diffract sunlight and signal light into a common waveguide. Then, small-area solar cells convert the collected solar energy and power the system. Compact power supply components replace heavy batteries, thus contributing to the lightweight design. The simple acquisition and management of solar energy provide the system with sustainable self-charging capability. We believe that the lightweight design and continuous energy input solution will significantly promote the popularity of near-eye display in our daily lives.

Recently, infrared polarization imaging technology has become a research hotspot due to its ability to better resolve the physicochemical properties of objects and significantly enhance the target characteristics. However, the traditional infrared polarization imaging is limited to similar imaging mechanism restrictions, and it is difficult to acquire the polarization information of a wide-area posture in real time. Therefore, we report a combination of hardware and software for super-wide-field-of-view long-wave infrared gaze polarization imaging technology. Utilizing the non-similar imaging theory and adopting the inter-lens coupling holographic line-grid infrared polarization device scheme, we designed the infrared gazing polarized lens with a field-of-view of over 160°. Based on the fusion of infrared intensity images and infrared polarization images, a multi-strategy detail feature extraction and fusion network is constructed. Super-wide-field-of-view (150°×120°), large face array (1040×830), detail-rich infrared fusion images are acquired during the test. We have accomplished the tasks of vehicle target detection and infrared camouflage target recognition efficiently using the fusion images, and verified the superiority of recognizing far-field targets. Our implementation should enable and empower applications in machine vision, intelligent driving, and target detection under complex environments.

Photoacoustic microscopy (PAM) operating within the 1.7-μm absorption window holds great promise for the quantitative imaging of lipids in various biological tissues. Despite its potential, the effectiveness of lipid-based PAM has been limited by the performance of existing nanosecond laser sources at this wavelength. In this work, we introduce a 1725-nm hybrid optical parametric oscillator emitter (HOPE) characterized by a narrow bandwidth of 1.4 nm, an optical signal-to-noise ratio (OSNR) of approximately 34 dB, and a high spectral energy density of up to 480 nJ/nm. This advanced laser source significantly enhances the sensitivity of photoacoustic imaging, allowing for the detailed visualization of intrahepatic lipid distributions with an impressive maximal contrast ratio of 23.6:1. Additionally, through segmentation-based analysis of PAM images, we were able to determine steatosis levels that align with clinical assessments, thereby demonstrating the potential of our system for high-contrast, label-free lipid quantification. Our findings suggest that the proposed 1725-nm HOPE source could be a powerful tool for biomedical research and clinical diagnostics, offering a substantial improvement over current technologies in the accurate and non-invasive assessment of lipid accumulation in tissues.

Fourier ptychographic microscopy (FPM) is a promising technique for achieving high-resolution and large field-of-view imaging, which is particularly suitable for pathological applications, such as imaging hematoxylin and eosin (H&E) stained tissues with high space-bandwidth and reduced artifacts. However, current FPM implementations require either precise system calibration and high-quality raw data, or significant computational loads due to iterative algorithms, which limits the practicality of FPM in routine pathological examinations. In this work, latent wavefront denoting the unobservable exiting wave at the surface of the sensor is introduced. A latent wavefront physical model optimized with variational expectation maximization (VEM) is proposed to tackle the inverse problem of FPM. The VEM-FPM alternates between solving a non-convex optimization problem as the main task for the latent wavefront in the spatial domain and merging together their Fourier spectrum in the Fourier plane as an intermediate product by solving a convex closed-formed Fourier space optimization. The VEM-FPM approach enables a stitching-free, full-field reconstruction for Fourier ptychography over a 5.3 mm×5.3 mm field of view, using a 2.5× objective with a numerical aperture (NA) of 0.08. The synthetic aperture achieves a resolution equivalent to 0.53 NA at 532 nm wavelength. The execution speed of VEM-FPM is twice as fast as that of state-of-the-art feature-domain methods while maintaining comparable reconstruction quality.

Multicolor imaging has been widely applied across various biological and medical applications, especially essential for probing diverse biological structures. However, existing multicolor imaging methods often sacrifice either simultaneity or speed, posing a challenge for simultaneous imaging of over three fluorophores. Here, we proposed off-axis spectral encoding multicolor microscopy (OSEM) with a single camera that simultaneously captures encoded multicolor signals and reconstructs monochromatic images by decoding. Based on the natural intensity modulation difference of a single illumination spot across off-axis detection positions, we adjusted the multicolor excitation beams with distinct off-axis offsets from the same detection position to achieve spectral encoding. The method achieved multicolor simultaneous imaging in a single camera without extra sacrifice of frame rate. We evaluated OSEM’s imaging performance by imaging multicolor synthetic samples and fluorescent microbeads. We also demonstrated that OSEM reduced imaging time by 5.8 times and achieved 99% accuracy in classifying and counting multicolor fluorescent bacteria, outperforming sequential imaging. We obtained four-color fluorescent optical-sectioning images of a mouse brain slice at a speed of 2.85 mm2/s, demonstrating its effectiveness for high-throughput multicolor imaging of large tissue samples. These results indicate that OSEM offers a reliable and efficient tool for multicolor fluorescent imaging of large biological tissues.

Compressed ultrafast photography (CUP) is a computational imaging technique that can simultaneously achieve an imaging speed of 1013 frames per second and a sequence depth of hundreds of frames. It is a powerful tool for observing unrepeatable ultrafast physical processes. However, since the forward model of CUP is a data compression process, the reconstruction process is an ill-posed problem. This causes inconvenience in the practical application of CUP, especially in those scenes with complex temporal behavior, high noise level and compression ratio. In this paper, the CUP system model based on spatial-intensity-temporal constraints is proposed by adding an additional charge-coupled device (CCD) camera to constrain the spatial and intensity behaviors of the dynamic scene and an additional narrow-slit streak camera to constrain the temporal behavior of the dynamic scene. Additionally, the unsupervised deep learning CUP reconstruction algorithm with low-rank tensor embedding is also proposed. The algorithm enhances the low-rankness of the reconstructed image by maintaining the low-rank structure of the dynamic scene and effectively utilizes the implicit prior information of the neural network and the hardware physical model. The proposed joint learning model enables high-quality reconstruction of complex dynamic scenes without training datasets. The simulation and experimental results demonstrate the application prospect of the proposed joint learning model in complex ultrafast physical phenomena imaging.

Multi-angle illumination is a widely adopted strategy in various super-resolution imaging systems, where improving computational efficiency and signal-to-noise ratio (SNR) remains a critical challenge. In this study, we propose the integration of the iterative kernel correction (IKC) algorithm with a multi-angle (MA) illumination scheme to enhance imaging reconstruction efficiency and SNR. The proposed IKC-MA scheme demonstrates the capability to significantly reduce image acquisition time while achieving high-quality reconstruction within 1 s, without relying on extensive experimental datasets. This ensures broad applicability across diverse imaging scenarios. Experimental results indicate substantial improvements in imaging speed and quality compared to conventional methods, with the IKC-MA model achieving a remarkable reduction in data acquisition time. This approach offers a faster and more generalizable solution for super-resolution microscopic imaging, paving the way for advancements in real-time imaging applications.

Linearly chirped microwave waveforms (LCMWs) are indispensable in advanced radar systems. Our study introduces and validates, through extensive experimentation, the innovative application of a thin-film lithium niobate (TFLN) photonic integrated circuit (PIC) to realize a Fourier domain mode-locked optoelectronic oscillator (FDML OEO) for generating high-precision LCMW signals. This integrated chip combines a phase modulator (PM) and an electrically tuned notch micro-ring resonator (MRR), which functions as a rapidly tunable bandpass filter, facilitating the essential phase-to-intensity modulation (PM-IM) conversion for OEO oscillation. By synchronizing the modulation period of the applied driving voltage to the MRR with the OEO loop delay, we achieve Fourier domain mode-locking, producing LCMW signals with an impressive tunable center frequency range of 18.55 GHz to 23.59 GHz, an adjustable sweep bandwidth from 3.85 GHz to 8.5 GHz, and a remarkable chirp rate up to 3.22 GHz/μs. Unlike conventional PM-IM based FDML OEOs, our device obviates the need for expensive tunable lasers or microwave sources, positioning it as a practical solution for generating high-frequency LCMW signals with extended sweep bandwidth and high chirp rates, all within a compact and cost-efficient form factor.

Chip-based soliton frequency microcombs combine compact size, broad bandwidth, and high coherence, presenting a promising solution for integrated optical telecommunications, precision sensing, and spectroscopy. Recent progress in ferroelectric thin films, particularly thin-film lithium niobate (LiNbO3) and thin-film lithium tantalate (LiTaO3), has significantly advanced electro-optic (EO) modulation and soliton microcombs generation, leveraging their strong third-order nonlinearity and high Pockels coefficients. However, achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena. These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation. Here, following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach, we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once, and implement a facile method for soliton formation and its long-term stabilization in integrated X-cut LiTaO3 microresonators for the first time, to the best of our knowledge. The resulting mode-locked states exhibit robust stability against perturbations, enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.

A low noise oscillator is a crucial component in determining system performance in modern communication, microwave spectroscopy, microwave-based sensing (including radar and remote sensing), and metrology systems. In recent years, ultra-low phase noise photonic microwave oscillators based on optical frequency division have become a paradigm shift for the generation of high performance microwave signals. In this work, we report on-chip low phase noise photonic microwave generation based on spiral resonator referenced lasers and an integrated electro-optical frequency comb. Dual lasers are co-locked to an ultra-high-Q silicon nitride spiral resonator and their relative phase noise is measured below the cavity thermal noise limit, resulting in record low on-chip optical phase noise. A broadband integrated electro-optic frequency comb is utilized to divide down the relative phase noise of the spiral resonator referenced lasers to the microwave domain, resulting in record-low phase noise for chip-based oscillators (-69 dBc/Hz at 10 Hz offset, and -144 dBc/Hz at 10 kHz offset for a 10 GHz carrier scaled from 37.3 GHz output). The exceptional phase noise performance, planar chip design, high technology readiness level, and foundry-ready processing of the current work represent a major advance of integrated photonic microwave oscillators.

In this study, we developed a robust, ultra-wideband, and high-speed wavelength-swept distributed feedback (DFB) laser array with an 8×3 matrix interleaving structure with no movable or fragile optical components. This wavelength-swept laser (WSL) achieves a continuous (gap-free) wavelength sweeping range of 60 nm and a rapid sweeping speed of 82.7 kHz, marking the widest wavelength sweeping range reported to date for high-speed WSLs based on DFB laser arrays, to our knowledge. To achieve the high-precision mapping from the time domain to the frequency domain, a nonlinear wavelength and frequency variation measurement system based on dual Fabry–Perot (F-P) etalons is designed. The system accurately measures the dynamic relationship of frequency variations over time, enabling precise wavelength interrogation. The proposed WSL was applied to the fiber Bragg grating (FBG) sensor interrogation system. In the high-low temperature and strain experiments, the system performed real-time dynamic interrogation of FBGs for up to 3 h. The experimental results demonstrated good relative accuracy and excellent interrogation performance of the system. In the vibration experiment, the system achieved high-precision interrogation of FBG sensors for high-frequency sinusoidal vibrations up to 8 kHz. Furthermore, the system worked stably under strong vibrations and shocks. Thus, the proposed WSL is applicable to high-speed FBG sensing and optical coherence tomography applications.

Effective detection schemes for spatiotemporal light fields hold significant importance in the study of high-dimensional spatiotemporal nonlinear systems. We propose a compact seven-core fiber spatiotemporal mapping system (SCF-SMS) to investigate the transient dynamics within a spatiotemporal mode-locked (STML) fiber laser. By utilizing this system, we observed intriguing transient phenomena during STML processes, including beating dynamics and spatiotemporal soliton state transition dynamics. In the beating dynamics, two channels corresponding to distinct spatial sampling points exhibited different transient behaviors. Conversely, during the spatiotemporal soliton state transition dynamics, the transition processes of two channels were asynchronous, with observable discrepancies before and after the transitions. Compared with existing spatiotemporal light field acquisition methods, the SCF-SMS enables more compact spatiotemporal mapping within STML fiber lasers. This real-time, synchronous system for spatiotemporal soliton information measurement facilitates an in-depth study of nonlinear dynamical phenomena in STML fiber lasers.

Submicron-thick thin-film lithium niobate (TFLN) has emerged as a promising platform for nonlinear integrated photonics. In this work, we demonstrate the efficient simultaneous generation of broadband 2nd–8th harmonics in chirped periodically poled (CPP) TFLN. This is achieved through the synergistic effects of cascaded χ(2) nonlinear up-conversion and χ(3) self-phase modulation, driven by near-infrared femtosecond pulses with a central wavelength of 2100 nm and a pulse energy of 1.2 μJ. Remarkably, the 7th and 8th harmonics extend into the deep ultraviolet (DUV) region, reaching wavelengths as short as 250 nm. The 3rd–8th harmonic spectra seamlessly connect, forming a broadband supercontinuum spanning from the DUV to the visible range (250–800 nm, -25 dB), with an on-chip conversion efficiency of 19% (0.23 μJ). This achievement is attributed to the CPP-TFLN providing multiple broadband reciprocal lattice vector bands, enabling quasi-phase matching for a series of χ(2) nonlinear processes, including second harmonic generation (SHG), cascaded SHG, and third harmonic generation. Furthermore, we demonstrated the significant role of cascaded χ(2) phase-mismatched nonlinear processes in high-harmonic generation (HHG). Our work unveils the intricate and diverse nonlinear optical interactions in TFLN, offering a clear path toward efficient on-chip HHG and compact coherent white-light sources extending into the DUV.

An object or system is said to be chiral if it cannot be superimposed on its mirror reflection. Chirality is ubiquitous in nature, for example, in protein molecules and chiral phonons—acoustic waves carrying angular momentum—which are usually either intrinsically present or magnetically excited in suitable materials. Here, we report the use of intervortex forward Brillouin scattering to optically excite chiral flexural phonons in a twisted photonic crystal fiber, which is itself a chiral material capable of robustly preserving circularly polarized optical vortex states. The phonons induce a spatiotemporal rotating linear birefringence that acts back on the optical vortex modes, coupling them together. We demonstrate intervortex frequency conversion under the mediation of chiral flexural phonons and show that, for the same phonons, backward and forward intervortex conversion occurs at different wavelengths. The results open up, to our knowledge, new perspectives for Brillouin scattering and the chiral flexural phonons offer new opportunities for vortex-related information processing and multi-dimensional vectorial optical sensing.

Current synaptic characteristics focus on replicating basic biological operations, but developing devices that combine photoelectric responsiveness and multifunctional simulation remains challenging. An optoelectronic transistor is presented, utilizing a PMHT/Al2O3 heterostructure for photoreception, memory storage, and computation. This artificial synaptic transistor processes optical and electrical signals efficiently, mimicking biological synapses. The work presents four logic functions: “AND”, “OR”, “NOR”, and “NAND”. It demonstrates electrical synaptic plasticity, optical synaptic plasticity, sunburned skin simulation, a photoelectric cooperative stimulation model for improving learning efficiency, and memory functions. The development of heterostructure synaptic transistors and their photoelectric response enhances their application in neuromorphic computation.

Engineering ultrashort laser pulses is crucial for advancing fundamental research fields and applications. Controlling their spatiotemporal behavior, tailored to specific applications, can unlock new experimental capabilities. However, achieving this control is particularly challenging due to the difficulty in independently structuring their intensity and spatial phase distributions, given their polychromatic bandwidth. This article addresses this challenge by presenting a technique for generating flying structured laser pulses with tunable spatiotemporal behavior. We developed a comprehensive approach to directly design and govern these laser pulses. This method elucidates the role jointly played by the pulse’s spatiotemporal couplings and its prescribed phase gradient in governing the pulse dynamics. It evidences that the often-overlooked design of the phase gradient is indeed essential for achieving programmable spatiotemporal control of the pulses. By tailoring the prescribed phase gradient, we demonstrate the creation of, to our knowledge, novel families of flying structured laser pulses that travel at the speed of light in helical spring and vortex multi-ring forms of different geometries. The achieved control over the dynamics of their intensity peaks and wavefronts is analyzed in detail. For instance, the intensity peak can be configured as a THz rotating light spot or shaped as a curve, enabling simultaneous substrate illumination at rates of tens of THz, far exceeding the MHz rates typically used in laser material processing. Additionally, the independent manipulation of the pulse wavefronts allows local tuning of the orbital angular momentum density carried by the beam. Together, these advancements unveil advantageous capabilities that have been sought after for many years, especially in ultrafast optics and light-matter interaction research.

The nitrogen-vacancy (NV) color center in diamond is a promising solid-state quantum system at room temperature. However, its sensitivity is limited by its low fluorescence collection efficiency, and its coherence time is limited by spin interference of impurity electrons around the NV color center. Here, we innovatively fabricated a one-dimensional photonic crystal on the surface of diamond, which greatly improved the fluorescence intensity of the NV color centers and increased the sensitivity of NV ensembles by a factor of 2.92. In addition, the laser reflected by the photonic crystal excites impurity electrons around the NV color centers, improving the electric field environment around the NV color centers, which exponentially prolongs the dephasing time (from 209 to 841 ns), opening avenues for NV color-center ensemble sensors.

A hybrid entangled state that involves both discrete and continuous degrees of freedom is a key resource for hybrid quantum information processing. It is essential to characterize entanglement and quantum coherence of the hybrid entangled state toward the application of it. Here, we experimentally characterize the entanglement and quantum coherence of the prepared hybrid entangled state between a polarization-encoded discrete-variable qubit and a cat-encoded wave-like continuous-variable qubit. We show that the maximum quantum coherence is obtained when the probability of the horizontal-polarization photon is 0.5, and entanglement and quantum coherence of the hybrid entangled state are robust against loss in both discrete- and continuous-variable parts. Based on the experimentally reconstructed two-mode density matrix on the bases of polarization and cat state, we obtain the logarithm negativity of 0.57 and l1-norm of 0.82, respectively, which confirms the entanglement and quantum coherence of the state. Our work takes a crucial step toward the application of the polarization-cat hybrid entangled state.

Programmable photonic integrated circuits (PICs) have emerged as a promising platform for analog signal processing. Programmable PICs, as versatile photonic integrated platforms, can realize a wide range of functionalities through software control. However, a significant challenge lies in the efficient management of a large number of programmable units, which is essential for the realization of complex photonic applications. In this paper, we propose an innovative approach using Ising-model-based intelligent computing to enable dynamic reconfiguration of large-scale programmable PICs. In the theoretical framework, we model the Mach–Zehnder interferometer (MZI) fundamental units within programmable PICs as spin qubits with binary decision variables, forming the basis for the Ising model. The function of programmable PIC implementation can be reformulated as a path-planning problem, which is then addressed using the Ising model. The states of MZI units are accordingly determined as the Ising model evolves toward the lowest Ising energy. This method facilitates the simultaneous configuration of a vast number of MZI unit states, unlocking the full potential of programmable PICs for high-speed, large-scale analog signal processing. To demonstrate the efficacy of our approach, we present two distinct photonic systems: a 4×4 wavelength routing system for balanced transmission of four-channel NRZ/PAM-4 signals and an optical neural network that achieves a recognition accuracy of 96.2%. Additionally, our system demonstrates a reconfiguration speed of 30 ms and scalability to a 56×56 port network with 2000 MZI units. This work provides a groundbreaking theoretical framework and paves the way for scalable, high-speed analog signal processing in large-scale programmable PICs.

To adapt to the complex environment where low infrared emissivity and high infrared emissivity coexist, a radar stealth-infrared camouflage compatibility metasurface requires meta-atoms with customized infrared emissivity. Generally, the infrared emissivity is determined by the occupation ratio. However, the high occupation ratio will interfere with the scattering reduction function due to the Lorentz resonance from the metal patch. To address the problem, a method for decoupling Lorentz resonance is proposed in this paper. By shifting the resonant frequency of the metal patch to a high frequency, the Lorentz resonance is suppressed in the frequency band of scattering reduction. To verify the method, a single functional layer metasurface with microwave scattering reduction and customized infrared emissivity is designed. The scattering reduction at 3.5–5.5 GHz is realized through the polarization conversion. Meanwhile, the infrared emissivity of the metasurface can be gradient-designed by changing the occupation ratios of the meta-atoms. Compared with the initial design, the improved metasurface expands the infrared emissivity range from 0.60–0.80 to 0.51–0.80, and the scattering reduction effect remains unchanged. The experimental results agree with the simulated results. The work enriches the infrared emissivity function, which can be applied to camouflage in complex spectrum backgrounds.

Programmable metasurfaces are revolutionizing the field of communication and perception by dynamically modulating properties such as amplitude and phase of electromagnetic (EM) waves. Nevertheless, it is challenging for existing programmable metasurfaces to attain fully independent dynamic modulation of amplitude and phase due to the significant correlation between these two parameters. In this paper, we propose a radiation-type metasurface that can realize radiation space-time coding of the joint amplitude-phase. Hence, independent and arbitrary modulation of amplitudes and phases can be achieved for both x-polarized and y-polarized EM waves. For demonstration, the dynamic beam scanning with ultra-low sidelobe levels (SLLs) is validated. Moreover, we propose a strategy of stochastic coding and non-uniform modulation to suppress the harmonic energy, thereby obtaining the ultra-low sideband levels (SBLs). Prototypes were fabricated and measured, and all simulations and measurements demonstrated the superiority of the proposed strategy. In addition, the proposed strategy is optimization-free and highly integrated, which has unrivaled potential in the field of compact communication systems and radar systems.