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.

For the first time, to our knowledge, we demonstrate a six-mode transmission over a 960-km fiber link using in-line integrated amplification provided by a six-mode erbium-doped fiber amplifier (6M-EDFA) for a 28-GBaud dual-polarization QPSK signal. This transmission distance is five times longer than that of previously reported works. The integrated 6M-EDFA enabling this long-haul transmission exhibits modal gains of >17.6 dB, while the gains increase to 25 dB with an input power of -25 dBm. Importantly, a Gaussian-like erbium doping profile has been proposed to optimize the differential modal gain to 1.15 dB, ensuring a more uniform signal-to-noise ratio between spatial modes after long-haul transmission.

A conformal metasurface (MS) is required to load on a curved surface and both electromagnetic and mechanical performances need to be considered in practice. In this study, a bandpass circular-protrusion-jigsaw-shaped metasurface (CPJS-MS) is presented to meet the requirement of high mechanical character. In addition, a square-protrusion-jigsaw-shaped MS (SPJS-MS) is proposed, inspired by a mortise and tenon joint of ancient wooden architecture. First, the electromagnetic performance of a planar JS-MS is obtained using the equivalent circuit model (ECM) and simulation. Also, the polarization-independent angular stability for the two JS-MSs is compared with the conventional square-grid MS (SG-MS) to analyze the effect of protrusion structure on the pass band. Second, the transmission characteristics of the conformal JS-MS and SG-MS with different curvature radii are studied based on ECM. Then, the conformal stability of the three MSs is compared with infinite planar form under various incident angles and polarization states to further understand the conformal effect. Most importantly, mechanical properties, which are rarely reported, are discussed and compared. Finally, three MS samples are fabricated and measured to demonstrate the effectiveness and accuracy of the proposed MS designs. The analysis method is beneficial to further understanding electromagnetic and mechanical properties of conformal MSs.

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.

The state of polarization (SOP) on high-order Poincaré spheres (HOPSs), characterized by their distinctive phase profiles and polarization distributions, plays a crucial role in both classical and quantum optical applications. However, most existing metasurface-based implementations face inherent limitations: passive designs are restricted to represent a few predefined HOPS SOPs, while programmable versions typically constrain to 1-bit or 2-bit phase control resolution. In this paper, dynamic generation of HOPS beams with arbitrary SOP based on a transmissive space-time-coding metasurface is demonstrated. By combining 1-bit phase discretizations via PIN diodes with a time-coding strategy, the metasurface enables quasi-continuous complex-amplitude modulation for harmonic waves in both x- and y-polarizations. Based on near-field diffraction theory, arbitrary SOPs on any HOPSm,n can be precisely generated using a linearly polarized basis, which is independently controlled by FPGA reconfiguration. We experimentally demonstrate that polarization holography on HOPS0,0 achieves high polarization purity >91.28%, and vector vortex beams on HOPS1,3 and HOPS-1,3 exhibit high orbital angular momentum mode purities >91.25%. This methodology holds great potential for structured wavefront shaping, vortex generation, and high-capacity planar photonics.

Absorbing particles have attracted wide interest in multifarious fields due to their strong light absorption characteristics, which can be trapped by optical bottles (OBs), three-dimensional dark regions surrounded by light. Existing OB-based particle manipulation is typically limited to a single functionality, such as the stationary volume or the single manipulated object. This severely limits the versatility and selectivity of micro-manipulation, particularly in the multi-particle system. In this paper, we address these challenges by introducing a dynamic OBs generation method. By modulating optical vortices and multi-parabolic trajectory phases, a series of OBs with targeted positions, numbers, and states is encoded as a battery of holograms, which are imported into the spatial light modulator (SLM). Experimentally, by dynamically reconfiguring the corresponding holograms in the SLM, we validate selectively switching and moving OBs for dynamic particle manipulation. Consequently, a specific fraction of targeted particles can be selectively released, transported 7.2 mm away while the others remain trapped in place, or merged from two 3.5-mm-spaced OBs into a larger single entity. Our results deepen the applications of OB beams and may herald a new avenue for dynamic particle manipulation.

Due to the outstanding anti-interference capability against the ambient noise, LiDARs based on frequency-modulated continuous wave (FMCW) technology with high sensitivity and high signal-to-noise ratio (SNR) are essential to achieve ideal photodetection of weak light. To significantly improve the weak light detection performance of balanced photodetectors, this work first demonstrates a novel near-infrared germanium-on-silicon (Ge/Si) avalanche photodetector with a three-electrode balanced scheme. The single three-electrode avalanche photodetector exhibits a high responsivity of >200 A/W near breakdown voltage. The three-electrode balanced avalanche photodetector (3ele-BAPD) achieves a common-mode rejection ratio (CMRR) of 50 dB at an operating wavelength of 1550 nm. We have set up the FMCW coherent detection system. The minimum detectable power of -93 dBm can be achieved, corresponding to an SNR of 3.2 dB and a detection probability of 54%. In comparison, the performance exceeds that of the two-electrode balanced avalanche photodetector (2ele-BAPD), which exhibits a minimum detectable power of -85 dBm with a corresponding SNR of 3.1 dB and a detection probability of 51%. The superior weak light detection performance enables the 3ele-BAPD to accomplish 3D imaging based on the FMCW LiDAR scheme. Moreover, the 3ele-BAPD is also applied to velocity measurement for 4D sensing. The applications of LiDAR velocity measurement and imaging are verified.

Optical interconnects based on photonic integrated circuits (PICs) are emerging as a pivotal technology to address the relentless surge in data traffic driven by compute-intensive applications. Combining mode-division multiplexing (MDM) with wavelength-division multiplexing (WDM) offers a compelling approach to significantly enhance the shoreline density of optical interconnects. However, existing on-chip MDM systems encounter considerable challenges in simultaneously achieving a large optical bandwidth, multi-band operation, and ultra-compactness, thereby limiting scalability as conventional telecom band resources become increasingly constrained. Here we introduce, to our knowledge, the first inverse-designed multi-band mode multiplexer (MUX) utilizing a digital metamaterial structure to support the first three-order TE modes. The proposed device features an ultra-compact footprint of 6 μm×4.8 μm and exhibits an exceptionally flat spectral response, with numerical simulations confirming spectral variations of less than 0.94 dB across the 1500–2100 nm range. Experimental results further validate its performance, demonstrating insertion losses below 4.3 dB and 4.0 dB, and crosstalk below -11.6 dB and -11.3 dB, within the 1525–1585 nm and 1940–2040 nm bands, respectively. Additionally, system-level optical interconnect experiments using a multi-band MDM circuit successfully achieve single-wavelength transmission rates of 3-modes×180 Gb/s at the 1.55 μm band and record-setting 3-modes×114 Gb/s in the 2 μm band. This work highlights the transformative potential of employing multi-band MDM technology to enhance bandwidth density and scalability, providing a robust foundation for next-generation high-capacity on-chip optical interconnects.

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.

Multiplexing techniques have always been one of the important components of optical communication research. These techniques can transmit multiple signals in a shared information channel and can greatly increase the maximum capacity of an information channel. The Dirac-vortex cavity is a type of photonic crystal surface emission system, and its characteristics of miniaturization and high stability make it very suitable for on-chip optical system. In this paper, we realized dual-channel emission of the Dirac-vortex cavity, which is achieved by modulating the size and phase of hexagonal holes in the hexagon lattice. The characteristics of dual-channel emission are investigated by numerical simulation, and the dual-channel emission rules are summarized. The double Dirac-vortex cavity model is not only explored for its multiplexing capability but also as an alternative scheme for the application of Dirac-vortex cavity in multiplex communication systems.

We present a novel, to our knowledge, optical arbitrary waveform generation (OAWG) technique, termed four-wave optical-waveguided chirp-free ultrafast shaping (FOCUS), which utilizes four-wave mixing (FWM)-based spectral transcription. FOCUS enables the generation of chirp-free pulse sequences with independently adjustable duration, intensity, interval, and central wavelength of sub-pulses. Experimental validation demonstrates that the system achieves a 2 ps temporal resolution and a 400 ps record length while maintaining <1 nm spectral bandwidth, >30 dB extinction ratio, ∼1 nJ pulse energy consumption, and 3.5 nm continuous wavelength tunability. Fundamental analysis reveals that three key parameters govern temporal resolution: spectral shaper resolution (the current limiting factor), pump bandwidth (potentially expandable to 30 nm), and engineered group delay dispersion (GDD). Recent advancements in chip-scale mode-locked lasers, dispersion-engineered waveguides, and nonlinear FWM modules position the FOCUS platform as a promising candidate for next-generation ultrafast photonic systems designed for simultaneous sub-picosecond temporal resolution and nanosecond-scale waveform programmability within compact integrated architectures.

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.