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Photogating effect is the dominant mechanism of most high-responsivity two-dimensional (2D) material photodetectors. However, the ultrahigh responsivities in those devices are intrinsically at the cost of very slow response speed. In this work, we report a WSe 2 /Ta 2 NiSe 5 heterostructure detector whose photodetection gain and response speed can be enhanced simultaneously, overcoming the trade-off between responsivity and speed. We reveal that photogating-assisted tunneling synergistically allows photocarrier multiplication and carrier acceleration through tunneling under an electrical field. The photogating effect in our device features low-power consumption (in the order of nW) and shows a dependence on the polarization states of incident light, which can be further tuned by source-drain voltages, allowing for wavelength discrimination with just a two-electrode planar structure. Our findings offer more opportunities for the long-sought next-generation photodetectors with high responsivity, fast speed, polarization detection, and multi-color sensing, simultaneously. Photodetectors based on 2D materials can exhibit high photoresponsivity, but usually at the cost of their response speed. Here, the authors report a strategy based on photogating-assisted tunneling to overcome this trade-off in WSe 2 /Ta 2 NiSe 5 heterostructures.

Differential interference contrast (DIC) microscopy allows high-contrast, low-phototoxicity, and label-free imaging of transparent biological objects, and has been applied in the field of cellular morphology, cell segmentation, particle tracking, optical measurement and others. Commercial DIC microscopy based on Nomarski or Wollaston prism resorts to the interference of two polarized waves with a lateral differential offset (shear) and axial phase shift (bias). However, the shear generated by these prisms is limited to the rectilinear direction, unfortunately resulting in anisotropic contrast imaging. Here we propose an ultracompact metasurface-assisted isotropic DIC (i-DIC) microscopy based on a grand original pattern of radial shear interferometry, that converts the rectilinear shear into rotationally symmetric along radial direction, enabling single-shot isotropic imaging capabilities. The i-DIC presents a complementary fusion of typical meta-optics, traditional microscopes and integrated optical system, and showcases the promising and synergetic advancements in edge detection, particle motion tracking, and label-free cellular imaging. The authors present a metasurface-assisted isotropic DIC microscopy technique. It is based on an original pattern of radial shear interferometry, that converts rectilinear shear into rotationally symmetric radial shear, enabling single-shot isotropic imaging capabilities.

Dispersion decomposes compound light into its monochromatic components, which is detrimental to broadband imaging but advantageous for spectroscopic applications. Metasurfaces provide a unique path to modulate the dispersion by adjusting structural parameters on a two-dimensional plane. However, conventional linear phase compensation does not adequately match the meta-unit’s dispersion characteristics with required complex dispersion, hindering at-will dispersion engineering over a very wide bandwidth particularly. Here, we propose an asymptotic phase compensation strategy for ultra-broadband dispersion-controlled metalenses. Metasurfaces with extraordinarily high aspect ratio nanostructures have been fabricated for arbitrary dispersion control in ultra-broad bandwidth, and we experimentally demonstrate the single-layer achromatic metalenses in the visible to infrared spectrum (400 nm~1000 nm, NA = 0.164). Our proposed scheme provides a comprehensive theoretical framework for single-layer meta-optics, allowing for arbitrary dispersion manipulation without bandwidth restrictions. This development is expected to have significant applications in ultra-broadband imaging and chromatography detection, among others. The authors present a comprehensive framework for on-demand dispersion control with a single-layer metasurface, particularly in an ultra-broad bandwidth. An achromatic metalens spanning the visible and near-infrared spectra is experimentally demonstrated.

Objects with different shapes, materials and temperatures can emit distinct polarizations and spectral information in mid-infrared band, which provides a unique signature in the transparent window for object identification. However, the crosstalk among various polarization and wavelength channels prevents from accurate mid-infrared detections at high signal-to-noise ratio. Here, we report full-polarization metasurfaces to break the inherent eigen-polarization constraint over the wavelengths in mid-infrared. This recipe enables to select arbitrary orthogonal polarization basis at individual wavelength independently, therefore alleviating the crosstalk and efficiency degradation. A six-channel all-silicon metasurface is specifically presented to project focused mid-infrared light to distinct positions at three wavelengths, each with a pair of arbitrarily chosen orthogonal polarizations. An isolation ratio of 117 between neighboring polarization channels is experimentally recorded, exhibiting detection sensitivity one order of magnitude higher than existing infrared detectors. Remarkably, the high aspect ratio ~30 of our meta-structures manufactured by deep silicon etching technology at temperature −150 °C guarantees the large and precise phase dispersion control over a broadband from 3 to 4.5 μm. We believe our results would benefit the noise-immune mid-infrared detections in remote sensing and space-to-ground communications. Dispersive eigen-polarization engineering enabled polychromatic full-polarization control in mid-infrared.

Conventional coherent light-field manipulation techniques inherently conflict with the spatiotemporal incoherence of thermal radiation sources. While recent advances in thermophotonics have facilitated directional thermal emission, arbitrary thermal wavefront control—a cornerstone for advanced functionalities like focusing and holography—remains an unaddressed challenge. Here, we report a generalized recipe of designing meta-emitters with lossy and lossless outer boundaries, that enables thermal emission with arbitrarily tailored wavefront. Lossy and lossless surfaces on two sides of the meta-emitter are synergistically coupled by a single-mode waveguide, transforming incoherent thermal photons to coherent surface waves for wavefront shaping functionalities. Designer surface mode of meta-emitter permits the independent optimization of photon lifetime and propagation length, thus enabling scalable spatial coherence engineering. For the proof of concept, we experimentally demonstrate near-diffraction-limited self-focusing emission, quasi-two-dimensional (quasi-2D) high-quality thermal holography without speckle noise and spatial-multiplexed holography. Coupling optimization further suggests that spatial coherence exceeding 1000 λ 0 are achievable. Our proposed meta-emitter establishes a paradigm-shifting framework to integrate stochastic thermodynamic emission with precision photonic engineering, opening avenues for information-rich thermal radiation technologies. Wavefront control is inherently incompatible with thermal incoherence in general. To address this challenge, the authors propose a meta-emitter architecture featuring two tailored grooves interconnected by a waveguide tunnel enabling the conversion of thermal photons into coherent surface waves, thereby experimentally demonstrating feasible thermal wavefront manipulation— including thermal self-focusing and holography.

Intensity, polarization and wavelength are intrinsic characteristics of light. Characterizing light with arbitrarily mixed information on polarization and spectrum is in high demand 1 – 4 . Despite the extensive efforts in the design of polarimeters 5 – 18 and spectrometers 19 – 27 , concurrently yielding high-dimensional signatures of intensity, polarization and spectrum of the light fields is challenging and typically requires complicated integration of polarization- and/or wavelength-sensitive elements in the space or time domains. Here we demonstrate that simple thin-film interfaces with spatial and frequency dispersion can project and tailor polarization and spectrum responses in the wavevector domain. By this means, high-dimensional light information can be encoded into single-shot imaging and deciphered with the assistance of a deep residual network. To the best of our knowledge, our work not only enables full characterization of light with arbitrarily mixed full-Stokes polarization states across a broadband spectrum with a single device and a single measurement but also presents comparable, if not better, performance than state-of-the-art single-purpose miniaturized polarimeters or spectrometers. Our approach can be readily used as an alignment-free retrofit for the existing imaging platforms, opening up new paths to ultra-compact and high-dimensional photodetection and imaging. By combining spatial and frequency dispersive thin-film interfaces with deep residual learning, a miniature photodetector allowing the acquisition of high-dimensional information on light in a single-shot fashion is described.

Ultra-wide bandgap gallium oxides offer tremendous possibilities to develop short-wave optoelectronic devices. However, it is formidably challenging to produce single-crystal gallium oxide wafer and develop high-performance high-dimensional optoelectronics. Here we show a liquid-metal-assisted strategy to directly synthesize and transfer single-crystal, large-area and ultrathin β-Ga O . Benefiting from the UV-exposure oxidation of liquid gallium and strong interaction with gallium, our β-Ga O film shows a 4-inch wafer-scale size, a 7.5-nm thickness and a flexible transfer operation. The solar-blind β-Ga O detector achieves high responsivity (16.3 A W ), fast response (<150 μs) and wide linear dynamic range (120 dB). By employing metasurface design, the anisotropy ratio reaches a record high value of 28.8 for Ga O -based detectors. Moreover, we develop a sundial-inspired metasystem to simultaneously detect the incident direction, polarization, and intensity of solar-blind irradiation. These findings illustrate the potential of high-quality Ga O wafer for high-dimensional photodetection, paving the way for next-generation solar-blind communications.

The power of controlling objects with mind has captivated a popular fascination to human beings. One possible path is to employ brain signal collecting technologies together with emerging programmable metasurfaces (PM), whose functions or operating modes can be switched or customized via on-site programming or pre-defined software. Nevertheless, most of existing PMs are wire-connected to users, manually-controlled and not real-time. Here, we propose the concept of remotely mind-controlled metasurface (RMCM) via brainwaves. Rather than DC voltage from power supply or AC voltages from signal generators, the metasurface is controlled by brainwaves collected in real time and transmitted wirelessly from the user. As an example, we demonstrated a RMCM whose scattering pattern can be altered dynamically according to the user’s brain waves via Bluetooth. The attention intensity information is extracted as the control signal and a mapping between attention intensity and scattering pattern of the metasurface is established. With such a framework, we experimentally demonstrated and verified a prototype of such metasurface system which can be remotely controlled by the user to modify its scattering pattern. This work paves a new way to intelligent metasurfaces and may find applications in health monitoring, 5G/6G communications, smart sensors, etc.