Efficient active control of optical nonlinearity has long been a critical goal for advancing nonlinear optoelectronic devices. However, this remains a significant challenge, as nonlinear susceptibilities are inherently dictated by the microscopic properties of materials. In this work, we propose a microscopic mechanism to electrically reconfigure the Kerr nonlinearity by modulating the concentration of free electrons in heavily doped semiconductors under a static bias. Our theory incorporates electrostatic and hydrodynamic frameworks to describe the electronic dynamics, demonstrating electrically tunable linear and nonlinear modulations. The power threshold of achieving optical bistability shows unprecedented tunability over 2 orders of magnitude, reaching values as low as $10\text{μ}\mathrm{W}$ through surface-charge control. These findings offer insights into understanding and actively controlling Kerr nonlinearities, paving the way for efficient refractive-index engineering as well as the development of advanced linear and nonlinear electro-optical modulators

Performing simultaneous depth-of-field (DOF) extension and edge enhancement within a single optical element remains a fundamental challenge in advanced imaging. Here, we propose a wavelength-tunable nonlocal Huygens metasurface capable of simultaneously extracting depth and edge features of images in a single-shot exposure. Using the selective polarization response of the Huygens metasurfaces, the circularly polarized converted component undergoes geometric phase modulation for wave-front shaping to extend the DOF, while the nonconverted component acts as a spatial frequency filter to enhance edge contrast. The integration of a phase-change material, ${\mathrm{Sb}}_2{\mathrm{S}}_3$, enables continuous tuning of the resonance wavelength across a range of 100 nm by modulating its refractive index, granting the system excellent broadband spectral adaptability. This work offers a compact solution for real-time depth sensing and feature extraction in applications such as autonomous navigation and biomedical imaging.

Steering frequency combs with equal line spacing and high directivity are essential for applications in precision measurement, wireless communication, and radar detection. However, existing approaches typically separate frequency comb generation from beam steering, requiring precise phase locking and multiple discrete devices. These systems not only demand ample space to accommodate multiple device structures, but also impose strict demands on physical integration and engineering implementation. Here, we present a multicolor space-time modulation approach based on programmable waveguide antennas that integrates frequency comb generation and beam steering into a single device. Using coupled-mode theory, we first validate the scattering modes in the momentum-frequency plane for monochromatic space-time modulation. We further generalize the framework to incorporate multicolor space-time modulation, achieving simultaneous control over beam-steering direction, comb line spacing, and intensity. By unifying comb generation and beam steering within a single device, our work offers a compact and reconfigurable solution for photonic and microwave systems.

Facilitated by low-noise laser-frequency locking, optical microresonators with the Pockels effect have shown unprecedented high resolutions in sensing electrical field. However, the requirement for tunable and low-noise laser sources considerably increases the cost and the size of the system, thereby limiting the industrial applicability of the microresonator-based technology. Here, we explore the possibility of using a low-cost fixed-frequency semiconductor laser as the pump laser to perform radiofrequency electrometry. A resonant mode in a lithium niobate microresonator is frequency locked to the laser using the electrooptic effect. This same effect also underlies the radiofrequency electric-field sensing mechanism. Our experimental results show that the electrometry resolution can be maintained at signal frequencies beyond the optical resonance bandwidth and that the signal-to-noise ratio does not change with varied coupling conditions as long as the laser frequency noise is the dominant noise source of the system. In addition, narrowband electrooptic sensitivity enhancement is observed at frequencies of the microresonator’s piezoelectric resonances, resulting in a resolution enhancement factor of approximately 3 at signal frequencies around 4 MHz. Our work advances the photonic resonant electrometry technology by studying the bandwidth limitation, and opens the road to the employment of low-cost lasers in high-resolution sensing applications.

Integration of two-dimensional (2D) ferroelectric materials into van der Waals (vdW) heterostructures offers a promising strategy for enhancing photocatalytic efficiency. Herein, we reveal the electronic structures and photoexcited carrier dynamics in ${\mathrm{Cu}\mathrm{In}\mathrm{P}}_2{\mathrm{S}}_6/\mathrm{Si}\mathrm{C}$ heterostructures, using first-principles and nonadiabatic molecular dynamics simulations. Both the down- and up-polarization configurations exhibit a type-II charge-separation mechanism with ultrafast electron (hole) transfer within about 58 fs (110 fs), accompanied by long carrier lifetime scales of several nanoseconds. Notably, switching ${\mathrm{Cu}\mathrm{In}\mathrm{P}}_2{\mathrm{S}}_6$ ferroelectric polarization from up to down exhibits a low polarization-reversal energy barrier (0.32 eV) and reduces nonadiabatic coupling in the recombination process, due to weakened electron-phonon coupling and accelerated quantum decoherence, thereby suppressing electron-hole recombination and prolonging its lifetime from 1.04 to 3.44 ns. These findings demonstrate that ${\mathrm{Cu}\mathrm{In}\mathrm{P}}_2{\mathrm{S}}_6/\mathrm{Si}\mathrm{C}$ has great promise for photocatalysis using 2D ferroelectric vdW heterostructures.

Anisotropic optical response in two-dimensional (2D) black phosphorene (BP) has attracted intense interest in condensed matter physics and materials science. The strong contrast in the optical response between lights polarized along the in-plane two orthogonal directions gives rise to wide applications in optoelectronics, such as optical polarizers and photodetectors. Expanding the family of anisotropic 2D materials toward a wider spectrum is, therefore, highly desirable. Here, based on a many-body perturbation method, we have investigated the quasiparticle band structure, exciton states, and optical properties in three niobium oxide dihalides $\mathrm{Nb}\mathrm{O}{X}_2$ ($X=\mathrm{I},\mathrm{Br},\mathrm{Cl}$). Similar to 2D transition-metal dichalcogenides, e.g., ${\mathrm{Mo}\mathrm{S}}_2$, the strong exciton effect has been identified in these 2D systems. However, in addition to the enhanced electron-hole interaction from unusual 2D screening, the flat bands revealed in the three 2D systems make the electron-hole excitation closer to Frenkel type. In the meantime, the anisotropic 2D crystal structure makes the exciton excitation orientationally preferred and consequently giant linear dichroism. Compared with anisotropic BP, violet phosphorene (VP), monochalcogenides $AB$ ($A=\mathrm{Ge}$ and $\mathrm{Sn}$; $B=\mathrm{S}$ and $\mathrm{Se}$), and magnetic $\mathrm{Cr}\mathrm{SBr}$, these niobium oxide dihalides exhibit much stronger optical anisotropy. In particular, for incident light at the wavelength of near ultraviolet, ultraviolet, and deep ultraviolet, the polarization rotation angle for reflected light exceeds $9^{\circ }$ and hyperbolic exciton-polaritons could be realized, guaranteeing their potential applications in 2D anisotropic optoelectronics.

A method for efficient isotope separation is proposed, based on efficient photoionization of atoms by a continuous-wave laser using resonant enhancement in an ultralarge volume optical cavity. This method should enable higher efficiency than the existing state of the art and could be used as an alternative to radiochemistry. It should also allow separation of radioisotopes that are not amenable to standard radiochemistry, with important implications for medicine.

Blockages—common in pipelines, microchannels, and vascular networks—dramatically disrupt laminar flow, amplify energy dissipation, and threaten system efficiency, posing a critical challenge across industrial and biomedical domains. Current hydrodynamic metamaterial solutions frequently employ viscosity tuning, an approach that faces challenges due to stringent precision requirements and limited operational flexibility. We experimentally demonstrate a paradigm shift: a geometric carpet cloak that restores undisturbed flow profiles and eliminates the blockage-induced pressure drop across diverse flow conditions and blockage geometries, without any need to adjust material parameters. Our design approach enables advanced hydrodynamic metadevices, such as flow splitters and combiners, that can partition liquids while rapidly restoring a uniform, parallel downstream flow profile. This flow-collimating capability is crucial for creating densely packed, low-crosstalk microfluidic circuits. Our work connects metamaterial theory to practical liquid engineering, offering new strategies for high-fidelity flow management and flow-field engineering.

The need for reconfigurable and energy-efficient logic systems in modern computing has led to growing interest in spintronic devices. Spin-orbit-torque magnetic tunnel junctions (SOT MTJs) present an effective solution, enabling fast and low-power logic operations without requiring external magnetic fields. In this work, we introduce a reconfigurable SOT MTJ device capable of performing seven distinct Boolean logic operations: and, or, nand, nor, not, xor, and xnor. The device leverages the unique properties of spin-orbit torque to dynamically switch between two circuit configurations, with the input voltages controlling the logic gate function. Experimental results demonstrate the successful implementation of all seven gates, validating the device’s efficiency and versatility. This work highlights the potential of SOT MTJs for scalable, low-power spintronic logic systems, offering a promising path for next-generation reconfigurable computing applications.

We theoretically design and experimentally demonstrate a mechanism to protect intercavity polaritons, a mixed light-matter excitation in strongly coupled optical cavities. This arises from the strategic design of the energy-level landscape, which provides a direct connection with the transparency window, typically discussed in the context of slow light. The protection manifests itself as a remarkable robustness of the intercavity polariton dispersion over a wide momentum range, uncompromised photon-exciton mixing, and spatial separation of its photonic and excitonic components. The consequent tunable heavy mass opens avenues for exploring and using this unique optical excitation in advanced photonics.

Speaker localization is critical technology with applications in smart homes, surveillance, and robotics, particularly for enhancing human-machine interactions. Traditional localization methods typically rely on large sensor arrays, which add hardware complexity and cost. To address this limitation, this work presents an approach that combines an anisotropic acoustic metamaterial antenna (AMA) with a deep-learning-based voiceprint recognition (VPR) algorithm to achieve speaker localization using only a single microphone. The anisotropic modulation of speech signals by our proposed subwavelength AMA is the core mechanism enabling the method, constituting the physical foundation for single-microphone speaker localization. Our approach can achieve an impressive localization accuracy of 99.4% with speaker-independent and text-independent features, demonstrating robustness in distinguishing speakers from various directions. Numerical calculations are developed to confirm the orthogonality of frequency modulation across channels, enabling the extraction of directional information from speech. These modulated data are then processed using a VPR model to localize the speaker. Experiments were conducted using the Zhvoice corpus dataset to train the VPR model across eight directions. The model, based on the ResNet18 architecture, is chosen for its balance between performance and computational efficiency. The proposed system offers a low-complexity high-accuracy solution for speaker localization, with potential applications in smart devices and interactive systems. This research contributes to the field of human-machine interactions, offering a cost-effective and valid localization system for intelligent applications.

Quantum physics has brought enhanced capability in various sensing applications. Despite challenges from noise and loss in the radio-frequency (rf) domain, Xia et al. [Phys. Rev. Lett. 124, 150502 (2020)] demonstrated a route for enhanced rf-receiver empowered by quantum squeezing and entanglement. In this work, we further explore the quantum advantage of imaging in the weak coupling scenario of the rf-photonic receiver. The proposed imaging receiver applies a transducer to up-convert the rf signal to optical to enable high-efficiency connection via low-loss fiber networks. The efficient connection therefore increases the synthetic aperture and improves the resolution of the distributed imaging system. To overcome the challenge from low transduction efficiency in existing devices limited by weak photon interaction, we propose the use of squeezed-state optical sources to suppress the noise. We numerically evaluate the quantum advantage in synthetic aperture radar imaging, where the images are generated from the standard resolution test chart via a Gaussian point spread function with added Gaussian noise. We apply the Wiener filter on the images to restore the objects and find that stronger squeezing significantly improves the quality of the restored image. Our findings push quantum squeezing advantage to real-world applications.

We conduct an experimental investigation into the conservation of the twist phase in twisted Gaussian Schell model (TGSM) beams during both up- and down-conversion three-wave-mixing nonlinear processes. Independently generated TGSM beams, prepared with varying twist parameters, are used to pump and seed the nonlinear interactions. The resulting beams are then analyzed to determine their twist properties. Our findings demonstrate that the twists of the up- and down-converted beams depend on those of the pump and seed beams. Additionally, the results indicate that the twist phase is conserved throughout the process, in qualitative agreement with theoretical predictions. This study is motivated by the increasing potential applications of TGSM beams in various fields.

Spin waves (SWs) hold great potential for carrying information in future data transport and processing technologies. Generating SWs that combine high frequency with low damping using minimal energy is crucial for ultrafast and energy-efficient applications. In this paper, we investigate the laser-induced ultrafast magnetization dynamics in a coupled $\mathrm{Bi}\mathrm{YIG}/\mathrm{Co}$ heterostructure and compare the results with those obtained in bare $\mathrm{Bi}\mathrm{YIG}$. We demonstrate that femtosecond laser pulses can trigger high-frequency standing SWs in the BiYIG-based heterostructure with very low laser energy density, which cannot excite spin precession in bare BiYIG. We argue that the primary mechanism behind the excitation relates to ultrafast changes in the interlayer exchange field acting on BiYIG, caused by ultrafast laser heating of the adjacent $\mathrm{Co}$ layer. These results can open exciting perspectives for ultrafast and energy-efficient photomagnonics applications.