The integration of mid-infrared (MIR) photodetectors with built-in encryption capabilities holds immense promise for advancing secure communications in decentralized networks and compact sensing systems. However, achieving high sensitivity, self-powered operation, and reliable performance at room temperature within a miniaturized form factor remains a formidable challenge, largely due to constraints in MIR light absorption and the intricacies of embedding encryption at the device level. Here, a novel on-chip metamaterial-enhanced, 2D tantalum nickel selenide (Ta₂NiSe₅)-based photodetector, meticulously designed with a custom-engineered plasmonic resonance microstructure to achieve self-powered photodetection in the nanoampere range is unveiled. Gold cross-shaped resonators are demonstrated that generate plasmon-induced ultrahot electrons, significantly enhancing the absorption of MIR photons with energies far below the bandgap and boosting electron thermalization in Ta₂NiSe₅, yielding a 0.1 V bias responsivity of 47 mA/W-an order of magnitude higher than previously reported values. Furthermore, the implementation of six reconfigurable optoelectronic logic computing ("AND", "OR", "NAND", "NOR", "XOR", and "XNOR") are illustrated via tailored optical and electrical input-output configurations, thereby establishing a platform for real-time infrared-encrypted communication. This work pioneers a new direction in secure MIR communications, advancing the development of high-performance, encryption-capable photonic systems.

The switching speed of light polarization plays a crucial role in determining the upper-limit bandwidth of applications like optical communications and laser microscopy. However, conventional polarization elements based on macroscopic anisotropic crystals like birefringent crystals and chalcogenide glasses are either static or restricted by the low switching time of about hundreds of picoseconds. Here, a femtosecond-scale all-optical polarization controlling method is proposed through engineering the excited hot electrons in a graphene-loaded metasurface. Remarkably, a giant polarization orientation from left-handed polarization (LCP) to right-handed polarization (RCP) in the Poincaré sphere (≈80° rotation) is realized within only 200 fs in the mid-infrared. With pumping, the dedicated polarization-sensitive design allows the metasurface to exhibit a consistent resonance blueshift as the transient increase of the hot-electron temperature in graphene for y -polarized incidence. This polarization conversion approach features a giant modulation range and enables the reflected light to be dynamically and arbitrarily modulated into RCP, LCP, and linear states at femtosecond timescale. A few logic operations “AND”, “OR”, “NAND”, and “XOR” based on this method are also demonstrated by monitoring the normalized Stokes parameters. It is believed that this work may find practical application in next-generation signal-processing systems with large capacity.

The demand for broadband, room-temperature infrared, and terahertz (THz) detectors is rapidly increasing owing to crucial applications in telecommunications, security screening, nondestructive testing, and medical diagnostics. Current photodetectors face significant challenges, including high intrinsic dark currents and the necessity for cryogenic cooling, which limit their effectiveness in detecting low-energy photons. Here, we introduce a high-performance ultrabroadband photodetector operating at room temperature based on two-dimensional black arsenene (b-As) nanosheets. This device demonstrates responsivity across visible, near-infrared, and THz spectral ranges, with responsivities reaching 91.6 A/W at 520 nm, 6.3 A/W at 1550 nm, and 7.8 V/W at 0.27 THz. The exceptional THz responsivity is attributed to the use of plasma-wave rectification in antenna-integrated field-effect transistors with asymmetric antennas, enhancing light-matter interaction and facilitating nonlinear rectification within the two-dimensional electron gas of the transistor channel, achieving a voltage-dependent bipolar response. These advanced b-As-based photodetectors also enable secure THz communication through complex logic operations, achieving robust data encryption and high-performance signal processing.

Exciton transport is a fundamental process that underlies the functionality of semiconductor optoelectronicdevices. However, when excitons interact with one another, their transport pattern becomes unpredictable, posinga great challenge to harness their full potential in various applications. In our study, focusing on the excitondensity change in a tungsten-disulfide monolayer, we observed that strong interactions between excitons canactually stop their movement. This finding contradicts the typical understanding of consistent exciton movementand reveals that a higher density might decrease the exciton-exciton annihilation rate due to reduced mobility.Our findings offer a valuable technique to examine exciton transport and deepen our grasp of their behavior inmany-body interactions, which could pave the way for better-performing excitonic devices.

The heterojunction integration of two-dimensional (2D) materials via van der Waals (vdW) forces, unencumbered by lattice and processing constraints, constitutes an efficacious approach to enhance the overall optoelectronic performance of photodetectors, due to an assortment of distinctive light-matter interactions. Nonetheless, vdW heterojunction photodetectors based on transition metal dichalcogenides (TMDs) face an inevitable trade-off between low dark currents and high responsivity, curtailing the application potential of myriad novel optoelectronic components in sensing, spectral, and communication systems. In this study, we present the successful actualization of a highly sensitive, self-powered, and gate-tunable bipolar response photodetector. The mechanisms underlying photocurrent generation were scrutinized via bias-, power-, and position-dependent mapping photo-response measurements, identifying the photovoltaic effect, which is attributable to the Schottky junction’s built-in electric field, as the predominant mechanism. The prototype Au-WS 2 -graphene photodetector exhibits a remarkable light on/off ratio of 1.2 × 10 6 , a specific detectivity of 6.12 × 10 11 cm Hz 1/2 W −1 with 20 μs response time at 638 nm. The wide gate-tunable responsivity provides an adjustability scope, ranging from 0.9 to 3.1 A W −1 . Notably, the device demonstrates an exceptional linear photo-current response, with a linear dynamic range (LDR) value approximating 130 dB, which significantly surpasses that of other photodetectors based on TMDs.

The demand for miniaturized and integrated multifunctional devices drives the progression of high‐performance infrared photodetectors for diverse applications, including remote sensing, air defense, and communications, among others. Nonetheless, infrared photodetectors that rely solely on single low‐dimensional materials often face challenges due to the limited absorption cross‐section and suboptimal carrier mobility, which can impair sensitivity and prolong response times. Here, through experimental validation is demonstrated, precise control over energy band alignment in a type‐II van der Waals heterojunction, comprising vertically stacked 2D Ta2NiSe5 and the topological insulator Bi2Se3, where the configuration enables polarization‐sensitive, wide‐spectral‐range photodetection. Experimental evaluations at room temperature reveal that the device exhibits a self‐powered responsivity of 0.48 A·W−1, a specific directivity of 3.8 × 1011 cm·Hz1/2·W−1, a response time of 151 µs, and a polarization ratio of 2.83. The stable and rapid photoresponse of the device underpins the utility in infrared‐coded communication and dual‐channel imaging, showing the substantial potential of the detector. These findings articulate a systematic approach to developing miniaturized, multifunctional room‐temperature infrared detectors with superior performance metrics and enhanced capabilities for multi‐information acquisition.

In the More‐than‐Moore era, the explosive growth of data and information has driven the exploration of alternative non‐von Neumann computational paradigms. Photonic neuromorphic computing has emerged as a promising approach, offering high speed, wide bandwidth, and massive parallelism. Herein, a high‐resolution optical convolutional neural network (OCNN) is introduced using phase‐change material Ge2Sb2Te5 (GST)‐based microring hybrid waveguides. This on‐chip optical computing platform integrates GST into photonic devices, enabling versatile programming and in‐memory computing capabilities. Central to this platform is a photonic convolutional computational kernel, constructed from photonic switching cells embedded with GST on a microring resonator. This programmable photonic switch leverages the refractive index modulation during the GST phase transition to achieve up to 64 discrete levels of transmission contrast, suitable for representing matrix elements in neural network algorithms with 6‐bit resolution. Using these matrix elements, an OCNN capable of performing parallelized image edge detection and digital recognition tasks with high accuracy is demonstrated. The architecture is scalable for large‐scale photonic neural networks, offering ultrahigh computational throughput, a compact design, complementary metal‐oxide‐semiconductor‐compatible fabrication, and broad bandwidth.

Actuation of micro-objects along unconstrained trajectories in van der Waals contacting systems-in the same capacity as optical tweezers to manipulate particles in fluidic environments-remains a formidable challenge due to the lack of effective methods to overcome and exploit surface friction. Herein, a technique that aims to resolve this difficulty is proposed. This study shows that, by utilizing a moderate power beam of light, micro-objects adhered on planar solid substrates can be precisely guided to move in arbitrary directions, realizing sub-nanometer resolution across extended surfaces. The underlying mechanism is the interplay between surface friction and pulsed opto-thermo-elastic deformations, and to render a biased motion with off-centroid light illumination. This technique enables high-precision assembly, separation control of nanogaps, regulation of rotation angles in various material-substrate systems, whose capability is further tested in reconfigurable construction of optoelectronic devices. With simple set-up and theoretical generality, opto-thermo-elastic actuation opens up an avenue for versatile optical manipulation in the solid domain.

Light carries energy and momentum, laying the physical foundation of optical manipulation that has facilitated advances in myriad scientific disciplines, ranging from biochemistry and robotics to quantum physics. Utilizing the momentum of light, optical tweezers have exemplified elegant light–matter interactions in which mechanical and optical momenta can be interchanged, whose effects are the most pronounced on micro and nano objects in fluid suspensions. In solid domains, the same momentum transfer becomes futile in the face of dramatically increased adhesion force. Effective implementation of optical manipulation should thereupon switch to the "energy" channel by involving auxiliary physical fields, which also coincides with the irresistible trend of enriching actuation mechanisms beyond sole reliance on light-momentum-based optical force. From this perspective, this review covers the developments of optical manipulation in schemes of both momentum and energy transfer, and we have correspondingly selected representative techniques to present. Theoretical analyses are provided at the beginning of this review followed by experimental embodiments, with special emphasis on the contrast between mechanisms and the practical realization of optical manipulation in fluid and solid domains.

Uncooled broadband spectrum detection, spanning from visible to mid-wave-infrared regions, offers immense potential for applications in environmental monitoring, optical telecommunications, and radar systems. While leveraging proven technologies, conventional mid-wave-infrared photodetectors are encumbered by high dark currents and the necessity for cryogenic cooling. Correspondingly, innovative low-dimensional materials like black phosphorus manifest weak photoresponse and instability. Here, tantalum nickel selenide (Ta2NiSe5) infrared photodetectors with an operational wavelength range from 520 nm to 4.6 mu m, utilizing a hexagonal boron nitride (h-BN) encapsulation technique are introduced. The h-BN encapsulated metal-Ta2NiSe5-metal photodetector demonstrates a responsivity of 0.86 A W-1, a noise equivalent power of 1.8 x 10(-11) WHz(-1/2), and a peak detectivity of 8.75 x 10(8) cm Hz(1/2) W-1 at 4.6 mu m under ambient conditions. Multifaceted mechanisms of photocurrent generation in the novel device prototype subject are scrutinized to varying wavelengths of radiation, by characterizing the temporal-, bias-, power-, and temperature-dependent photoresponse. Moreover, the photopolarization dependence is delved and concealed-target imaging is demonstrated, which exhibits polarization angle sensitivity and high-fidelity imaging across the visible, short-wave, and mid-wave-infrared bands. The observations, which reveal versatile detection modalities, propose Ta2NiSe5 as a promising low-dimensional material for advanced applications in nano-optoelectronic device.

The increasing interest in two-dimensional materials with unique crystal structures and novel band characteristics has provided numerous new strategies and paradigms in the field of photodetection. However, as the demand for wide-spectrum detection increases, the size of integrated systems and the limitations of mission modules pose significant challenges to existing devices. In this paper, we present a van der Waals heterostructure photodetector based on Ta2NiSe5/WSe2, leveraging the inherent characteristics of heterostructures. Our results demonstrate that this detector exhibits excellent broad-spectrum detection ability from the visible to the infrared bands at room temperature, achieving an extremely high on/off ratio, without the need for an external bias voltage. Furthermore, compared to a pure material detector, it exhibits a fast response and low dark currents (~3.6 pA), with rise and fall times of 278 μs and 283 μs for the response rate, respectively. Our findings provide a promising method for wide-spectrum detection and enrich the diversity of room-temperature photoelectric detection.

Throughout, both the Auger-suppression effect and barrier-blocking devices have been regarded as highly promising solutions for achieving high- operation-temperature (HOT) in long-wave infrared (LWIR) HgCdTe devices. Herein, two structural designs of pBin-type barrier-blocking LWIR HgCdTe devices were introduced and analyzed, accompanied by an extensive investigation into the Auger-suppression effect within the designed structures. It was observed that this unique structural approach has the potential to enhance the operational temperature of HgCdTe barrier-blocking devices. A strong dependency of the Auger suppression effect on the doping concentration within the absorption region was revealed through the analysis of absorption region structural parameters. Furthermore, the analysis of band structures for different design configurations demonstrated that the structural design involving p-type barrier layers can effectively position the barrier at the conduction band, eliminating the reliance on valence band-offset with respect to barrier layer structural parameters. Consequently, the structural design and fabrication processes of the devices were significantly simplified. These discoveries offer theoretical guidance for the simplification of structural design and fabrication processes in HOT barrier-blocking HgCdTe devices, emphasizing the potential of pBin-type structures in enhancing device performance and achieving elevated operational temperatures.

Owing to the large built-in field for efficient charge separation, heterostructures facilitate the simultaneous realization of a low dark current and high photocurrent. The lack of an efficient approach to engineer the depletion region formed across the interfaces of heterojunctions owing to doping differences hinders the realization of high-performance van der Waals (vdW) photodetectors. This study proposes a ferroelectric-controlling van der Waals photodetector with vertically stacked two-dimensional (2D) black phosphorus (BP)/indium selenide (In2 Se3 ) to realize high-sensitivity photodetection. The depletion region can be reconstructed by tuning the polarization states generated from the ferroelectric In2 Se3 layers. Further, the energy bands at the heterojunction interfaces can be aligned and flexibly engineered using ferroelectric field control. Fast response, self-driven photodetection, and three-orders-of-magnitude detection improvements are achieved in the switchable visible or near-infrared operation bands. The results of the study are expected to aid in improving the photodetection performance of vdW optoelectronic devices.

Optical fibres with diameters at micro-or sub-micrometre scale are widely adopted as a convenient tool for studying light–matter interactions. To prepare such devices, two elements are indispensable: a heat source and a pulling force. In this paper, we report a novel fibre-tapering technique in which micro-sized plasmonic heaters and elaborately deformed optical fibres are compactly combined, free of flame and bulky pulling elements. Using this technique, micro-nano fibres with abrupt taper and ultra-short transition regions were successfully fabricated, which would otherwise be a challenge for traditional techniques. The compactness of the proposed system enabled it to be further transferred to a scanning electron microscope for in-situ monitoring of the tapering process. The essential dynamics of “heat and pull” was directly visualised with nanometre precision in real time and theoretically interpreted, thereby establishing an example for future in-situ observations of micro and nanoscale light-matter interactions.

It has been recently reported that elastic waves induced by nanosecond light pulses can be used to drive nanomotion of micro-objects on frictional solid interfaces, a challenging task for traditional techniques using tiny optical force. In this technique, the main physical quantities and parameters involved are tem-poral width and energy of light pulses, thermal heating and cooling time, friction force, and elastic waves. Despite a few experimental observations based on microfiber systems, a microscopic theory, which reveals how these quantities collaboratively enable motion of the micro-objects and derives what the underlying manipulation principles emerge, is absent. In this paper, a comprehensive theoretical analysis-centralized around the above listed physical quantities, and illuminated by a single-friction-point model in conjunction with numerical simulations-is established to pedagogically clarify the physics. Our results reveal the two essential factors in this technique: (1) the use of short light pulses for rapid thermal expansion overwhelm-ing friction resistance and (2) the timescale asymmetry in thermal heating and cooling for accumulating a net sliding distance. Moreover, we examine the effects of spatially distributed friction beyond the single -friction-point consideration, and show "tug-of-war"-like friction stretching in the driving process. Given these insights, we positively predict that this elastic-wave-based manipulation principle could be directly translated to micro-and nanoscale optical waveguides on optical chips, and propose a practical design. We wish that these results offer theoretical guidelines for ongoing efforts of optical manipulation on solid interfaces with light-induced elastic waves.

Manipulating motion of microobjects with light is indispensable in various technologies. On solid interfaces, its realizations, however, are hampered by surface friction. To resolve this difficulty, light-induced elastic waves have been recently proposed to drive microobjects against friction. Despite its expected applicability for arbitrary optical-absorptive objects, the new principle has only been tested with microsized gold plates. Herein, we validate this principle using a new material and report directional and continuous movements of a two-dimensional topological insulator (Sb2Te3) plate on an untreated microfiber surface driven by nanosecond laser pulses. The motion performance of the Sb2Te3 plate is characterized by a scanning electron microscope. We observe that the motion velocity can be controlled by tuning the average power of laser pulses. Further, by intentionally increasing the pulse repetition rate and exploiting the low thermal conductivity of Sb2Te3, we examine the thermal effects on actuation and reveal the motion instability induced by formations of microbumps on Sb2Te3 surfaces due to the Marangoni effects. Moreover, as the formed microbumps are heated to viscoelasticity states, liquid-like motion featuring asymmetry in contact angles is observed and characterized, which expands the scope of light-induced actuation of microobjects.

The transfer of angular momentum carried by photons into a microobject has been widely exploited to achieve the actuation of the microobject. However, this scheme is fundamentally defective in nonliquid environments as a result of the scale gap between friction forces ($\mu$N) and optical forces (pN). To bypass this challenge, the researchers have recently proposed to take advantage of elastic waves based on opto-thermo-mechanical effects [1-4]. Grounded on this insight, we here demonstrate and characterize the in-plane rotation of a gold nanoplate in its surface contacting with a microfiber, driven by nanosecond laser pulses, which has not been explored before. Furthermore, we examine the underlying physical mechanisms and highlight the essential role of the spatial gradient of optical absorption. The combined experimental and theoretical results offer new insights into the study of the light-induced actuation of the microobjects in nonliquid environments, an emerging field far from being mature in both comprehensive understanding and practical applications.

Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are pro-tected from backscattering,exhibiting electronic responses to light,such as topological quantum phase transi-tions.However,the effects of high-frequency driving topological intrinsic systems have remained largely unexplored challenges experimentally for high-sensitivity terahertz detection.In this study,by integrating Sb2Te3 topological insulators with subwavelength metal antennas through micro-nano processing,a high-frequency terahertz detector with high sensitivity is proposed.The enhanced response originates from the asymmetric scattering of the surface electrons in the Sb2Te3 flakes induced by the terahertz wave.The device displays room-temperature photodetection with a responsivity of 192 mA/W and equivalent noise power of less than 0.35 nW/Hz1/2 in the frequency range from 0.02 to 0.3 THz.These results pave the way for the ex-ploitation of topological insulators for high-frequency operation in real-time imaging within long-wavelength optoelectronics.

Optical Manipulation of Microobjects In article number 2100561, Wei Lyu, Weiwei Tang, Wei Yan, and Min Qiu realize in-plane rotation of a gold microplate on a microfiber by pulsed light. The motion is attributed to light-induced elastic waves other than ‘conventional’ optical force that is too tiny to tame friction between two solid interfaces. The underlying mechanisms highlight the joint role of spatial gradient of optical absorption and asymmetry in two wings of the plate, which lead to unbalanced, nonuniform elastic waves. The results offer new insights into the study of the light-induced actuation of microobjects in nonliquid environments.

The application of femtosecond laser-induced periodic surface texturing has significant potential in medicine, optics, tribology, and biology, among other areas. However, when irradiated by a large intense laser spot, the periodic structures usually exhibit an uncontrollable regularity, forming bifurcated patterns, thus limiting their widespread application. Irregularity originates from numerous independent branching seeds. The usual solution to this problem is to utilize the quasi-direct laser writing technique, that is, by limiting the laser beam size (diameter of < 10 wavelengths) and scanning the beam or samples using 2D translation stages. Herein, we demonstrate an optical localization-induced nonlinear competition mechanism to solve this problem, which occurs at a fluence nearly one order of magnitude below the ablation threshold. Owing to the low intrinsic absorption of silicon and ultralow applied fluence, this mechanism ensures the self-selection of a single seed to initiate an array of bifurcated-free gratings under stationary irradiation with a large laser spot (diameter > 100 wavelengths). Surprisingly, some unconventional complex patterns, such as radial, annular, and spiral gratings, can also be easily produced by structured light fields with unprecedented regularity. Their diameters reach up to > 0.5 mm. Moreover, we can artificially control the initial seeding structure to further improve the regularity of the gratings, defined by dispersion in the ripple orientation angle in their 2D Fourier transform. As a result, the regularity in our experiments produced by a large laser spot is even higher than that scanned by a tiny beam. Controllable and highly regular ripples are beneficial to the structural coloring effects because they arise from the light diffraction by subwavelength gratings.