Developing a feasible and effective crystallization approach to simultaneously amend microstructure and trap states in antimony sulfoselenide (Sb2(S,Se)3) absorber is extremely crucial and challenging for high-efficient solar cells. Herein, a regulation strategy is proposed to control crystallization process of Sb2(S,Se)3 using ionic liquids (ILs) consisted of halide (X) anions (Cl-, Br-, and I-) and [BMIM]+ cations. In particular, the [BMIM]Br creates a liquid microenviroment on Sb2(S,Se)3 surface before decomposition, accelerating the mass transfer, which induces micron-size grains. Moreover, the [BMIM]Br can promote the [211]-oriented growth via stronger adsorption on (211) facets of Sb2(S,Se)3. Additionally, the inhibited S and Se loss results in a near stoichiometric composition of Sb2(S,Se)3 film, which greatly raises the hole concentration and optimizes the band alignment. Very important transformation from severe antisite defect SbS to slight vacancy defect VSe2 remarkably suppresses the non-radiative recombination. As a result, with more effective carrier transport and collection, the [BMIM]Br-modulated device achieves a 10.89% efficiency and a 72.74% fill factor, which are separately one of the highest values for Sb2(S,Se)3 solar cells so far. This work shines a new light on breaking the bottleneck in the development of Sb2(S,Se)3 solar cells.

As an emerging photovoltaic material, antimony selenosulfide (Sb2(S,Se)3) has attracted considerable attention and research enthusiasm. However, the current solution-processed Sb2(S,Se)3 layers suffer from severe unfavorable energy band structure problems attributed to the vertical gradient-variable Se/S atomic ratio, making it a challenging and prospective subject. Herein, a novel and convenient alkali metal Cs+-induced Se/S atomic ratio variation strategy has been developed for the first time to regulate Sb2(S,Se)3 energy band structure through hydrothermal-processed CdS nanorod-arrays (NAs)/Sb2(S,Se)3 bulk heterojunction (BHJ) films. The Cs+-induced regulation strategy narrows Se-elemental concentration gradient distribution adjusting effectively Se/S atomic ratio in longitudinal CdS-NAs/Sb2(S,Se)3 BHJ films. This generates a favorable energy band structure, contributing to rapid charge separation and extraction of photogenerated carriers of CdS-NAs/Sb2(S,Se)3 BHJ. Meanwhile, the Cs+-induced Se/S ratio variation not only passivates the defect-state concentration and enhances crystal size of CdS-NAs/Sb2(S,Se)3 film, bust also extend the carrier lifetime for Sb2(S,Se)3 BHJ photovoltaic devices. The resulting Cs-Sb2(S,Se)3 BHJ photovoltaic devices exhibit an impressing power conversion efficiency (η) of 8.23%, the highest one currently available for Sb2(S,Se)3 BHJ solar cells. This study will undoubtedly facilitate the development of efficient Sb2(S,Se)3 BHJ devices, and other similar inorganic semiconductor photovoltaic devices.

This work presents a hybrid metamaterial platform integrating graphene, photosensitive silicon, and vanadium dioxide (VO2) to achieve dynamically tunable electromagnetically induced transparency (EIT) and polarization-selective frequency switching in the terahertz (THz) regime. The unit cell comprises a graphene cruciform (GC) resonator and four quarter graphene rings resonator (QGRs), enabling precise control of the EIT window’s amplitude and frequency through Fermi level modulation. The EIT effect exhibits robust angular insensitivity (<70°), with a frequency modulation depth of 0.176 and amplitude modulation depth of 0.907. Leveraging the light-driven conductivity of photosensitive silicon and the insulator-to-metal phase transition of VO2, the structure dynamically switches between slow-light states and enables single-/dual-frequency polarization-selective transmission at 1.26 THz, 1.85 THz, and 1.14/1.79 THz, achieving a modulation depth up to 92 %. This tri-material synergy overcomes the rigidity of conventional single-component systems, offering a reconfigurable framework for THz communication and sensing devices.

High performance infrared imaging devices have extensive applications in environmental monitoring, surveillance, and national defense. Pixelless upconversion imaging devices offer promising potential for large-format infrared imaging. In this work, we propose a pixelless upconversion imaging device enhanced by a microsphere (MS) structure. Fabricated through a convenient, low-cost, and efficient process, our device successfully achieved pixelless upconversion imaging of blackbody hot spots. Compared to prior methods, this design significantly improves the light extraction efficiency (LEE) while achieving an upconversion efficiency comparable to traditional grating structures. Theoretical analyses reveal that the external quantum efficiency (EQE) of the light-emitting diodes primarily drives the upconversion efficiency rather than the coupling efficiency of the quantum well detector. Finally, we present an optimized MS-coupled device with enhanced upconversion efficiency, providing insights for future development of large-format, high-efficiency, high-speed pixelless upconversion infrared imaging.

Crystalline Sb-2(S,Se)(3) has attracted considerable attention as light-harvesting material due to its excellent photovoltaic property. Herein, for the first time, K+-assisted deposition technique has been developed for hydrothermal-processed Sb-2(S,Se)(3) semiconductor film on CdS surface to fabricate high-quality Sb-2(S,Se)(3)/CdS heterojunction. The micro-morphologies (i.e., crystal size, heterojunction structure, element mapping) of the film are investigated through scanning electron microscopy (SEM). The electrical and optical properties are characterized by X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-vis) and space-charge-limited current (SCLC) methods. Eventually, the K+-doped photovoltaic device displays an encouraging power conversion efficiency (eta) of 8.96%, possessing one of the highest open circuit voltage (V-oc) of 0.69 V with CdS as the single electron transporting layer (ETL). Meanwhile, the reason why the K+-doped device boosts high V-oc has also been revealed in the Sb-2(S,Se)(3) solar cells.

A three-dimensional microscopic measurement based on gradient variance is proposed for focus evaluation to achieve high-precision focusing.Building upon the traditional Brenner evaluation function,this method incorporated information on changes in the grayscale gradient along the vertical and diagonal directions.Additionally,by capturing richer image edge details,it enhances the sensitivity of the focus evaluation function,thereby improving the accuracy of three-dimensional microscopic measurements.Experiments with a step sample having a nominal height of 1 mm were conducted,yielding a relative measurement error of 0.49%(relative to the standard value)for the proposed method,outperforming traditional focus evaluation methods with an error of 1.22%.Furthermore,for the evaluation function,the proposed method exhibits a clarity ratio and a sensitivity with values of 2.4412 and 318.45,respectively.

The introduction of liquid crystals into microcavities has garnered considerable attention for their exceptional tunability and high sensitivity to external perturbation factors within their distinct phase states. Here, a novel light source with both wavelength tunability and an exceptionally narrow linewidth is presented. This innovation is realized by strategically manipulating LC molecules, transitioning them from a well-aligned state to a disordered state with increasing temperature. The microcavity is tailored to support bound states in the continuum, a cutting-edge concept in photonic research that allows for light localization with minimal loss. In the pursuit of potential biocompatibility and to reduce cytotoxicity, indium phosphide colloid quantum dots are opted to serve as the emissive carriers within the system. An ultra-narrow linewidth light emission of 0.039 nm is observed, corresponding to a quality factor reaching 16668, along with a tunable range of 1.21 nm and a temperature sensitivity of 33.52 pm K-1. The invention's compact size and tunable character make it an ideal candidate for a variety of potential applications, such as eco-friendly sensors with minimal ecological impact, optical modulators with precise control over light, and adaptable photonic devices that can be integrated with a diverse array of materials and configurations. A tunable ultra-narrow linewidth light emission from a liquid-crystal-based photonic crystal cavity is experimentally demonstrated. The article thoroughly studies the design of cavities, ultra-narrow linewidth light sources based on InP quantum dot, and liquid crystal-assisted wavelength tuning. The devices exhibit a quality factor of 16 668, a sensitivity of 33.52 pm K-1, and a total tuning range of 25.7 nm. image

Metasurfaces made of subwavelength silicon nanopillars provide unparalleled capacity to manipulate light, and have emerged as one of the leading platforms for developing integrated photonic devices. In this study, we report on a compact, passive approach based on planar metasurface optics to generate large optical trap arrays. The unique configuration is achieved with a meta-hologram to convert a single incident laser beam into an array of individual beams, followed up with a metalens to form multiple laser foci for single rubidium atom trapping. We experimentally demonstrate two-dimensional arrays of 5 × 5 and 25 × 25 at the wavelength of 830 nm, validating the capability and scalability of our metasurface design. Beam waists ∼1.5 µm, spacings (about 15 µm), and low trap depth variations (8%) of relevance to quantum control for an atomic array are achieved in a robust and efficient fashion. The presented work highlights a compact, stable, and scalable trap array platform well-suitable for Rydberg-state mediated quantum gate operations, which will further facilitate advances in neutral atom quantum computing.

Antimony selenosulfide (Sb2(S,Se)3), featuring large absorption coefficient, excellent crystal structure stability, benign non-toxic characteristic, outstanding humidity and ultraviolet tolerability, has recently attracted enormous attention and research interest regarding its photoelectric conversion properties. However, the open-circuit voltage (Voc) for Sb2(S,Se)3-based photovoltaic devices is relatively low, especially for the device with a high power conversion efficiency (η). Herein, an innovative Se-elemental concentration gradient regulation strategy has been exploited to produce high-quality Sb2(S,Se)3 films on TiO2/CdS substrates through a thioacetamide(TA)-synergistic dual-sulfur source hydrothermal-processed method. The Se-elemental gradient distribution produces a favorable energy band structure, which suppresses the energy level barriers for hole transport and enhances the driving force for electron transport in Sb2(S,Se)3 film. This facilitates efficient charge transport/separation of photogenerated carriers and boosts significantly the Voc of Sb2(S,Se)3 photovoltaic devices. The champion TA-Sb2(S,Se)3 planar heterojunction (PHJ) solar cell displays an considerable η of 9.28 % accompanied by an exciting Voc rising to 0.70 V that is currently the highest among Sb2(S,Se)3-based solar cells with efficiencies exceeding 9.0 %. This research is anticipated to contribute to the preparation of high-quality Sb2(S,Se)3 thin film and the achievement of efficient inorganic Sb2(S,Se)3 PHJ photovoltaic device.

Broadband upconversion has various applications in solar photovoltaic, infrared and terahertz detection imaging, and biomedicine. The low efficiency of the light-emitting diodes (LEDs) limits the broadband upconversion performance. In this paper, we propose to use surface microstructures to enhance the electroluminescence efficiency (ELE) of LEDs. Systematical investigations on the cryogenic-temperature performances of microstructure-coupled LEDs, including electroluminescence efficiency, luminescence spectrum, and recombination rate, have been carried out by elaborating their enhancement mechanism and light emitting characteristics both experimentally and theoretically. We have revealed that the reason for the nearly 35% ELE enhancement of the optimized structure under cryogenic temperature and weak injection current is the efficient carrier injection efficiency and the high recombination rate in the active region. We also compare studies of the surface luminescence uniformity of the optimized LED with that of the unoptimized device. This work gives a precise description, and explanation of the performance of the optimized microstructure coupled LED at low temperatures, providing important guidance and inspiration for the optimization of broadband upconverter in the cryogenic temperature region.

In the realm of metasurface-based polarimetry, well-known for its remarkable compactness and integration capabilities, previous attempts have been hindered by limitations such as the restricted choices of target polarization states and the inefficient focusing of light. To address these problems, this study introduces and harnesses a novel, to our knowledge, forward-solving model, grounded in the equivalence principle and dyadic Green’s function, to inversely optimize the vectorial focusing patterns of metalenses. Leveraging this methodology, we develop and experimentally validate a single multi-foci metalens-based polarimeter, capable of simultaneously separating and concentrating four distinct elliptical polarization states at a wavelength of 10.6 µm. Rigorous experimental evaluations, involving the assessment of 18 scalar polarized beams, reveal an average error of 5.92% and a high contrast ratio of 0.92, which demonstrates the efficacy of the polarimeter. The results underscore the potential of our system in diverse sectors, including military defense, healthcare, and autonomous vehicle technology.

We introduce a fully connected neural network (FCNN) for predicting supercontinuum generation (SCG) in silicon waveguides. FCNN can predict SCG in silicon waveguides within one second. Experimental results demonstrate the predicting of SCG, correspondingly. (c) 2024 The Author(s)

Instead of the von Neumann architecture, logic-in-memory (LIM) provides a revolutionary approach to promoting computing efficiency. Based on the earlier work of complete LIM 16 Boolean logics, this article describes a memristor-based multiplexer (MUX) efficiently realized using a voltage/resistor-input-resistor-output (V/R-R) logic method, despite the fact that MUX is one of complicated logics in the design of VLSI circuits. Following that, a unique 2–1 MUX is further created by merging destructive resistor-input-resistor-output (R-R) logic with V/R-R logic, resulting in further device reduction. The 2–1 MUX only requires 3–4 memristors and four steps. Furthermore, the technique can be implemented for a 4–1 MUX using seven memristors and ten steps. Tests and simulations validated their feasibility and correctness. The effect of resistor due to the flip voltage variation on the computation accuracy is further analyzed, and the cascaded serial scheme of the MUX is finally presented.

The Q-switched laser sources on chip pave the way for the applications of laser processing, distance measurement and frequency conversion. In this work, using the monolayer graphene-silica hybrid waveguides with increased input optical power, Q-switched pulses with the pulse widths ranging from 1.57 mu s to 5.06 mu s and the repetition rates ranging from 47.23 kHz to 85.33 kHz are realized, which results in the maximum single pulse energy of 56.5 nJ. The interaction between graphene and propagation light in the waveguide is strengthened by coating the polymethyl methacrylate layer on the graphene-silica hybrid waveguide. The pump power threshold of Q -switching is reduced by a factor of 2.5, and the Q-switched pulses with pulse width of 1.21 mu s is achieved. Besides, as the pump power increases, the Q-switched mode-locking pulses are also observed.

Entangled photon pairs based on silicon straight waveguides have been applied in the area of quantum information owing to the compactness of the devices and high nonlinearity of the silicon material. In order to fully take advantage of the broad emission spectrum of photon pairs for quantum-key-distribution, dense wavelength division multiplexer (DWDM) is often required. However, the relationship between the channel bandwidth of DWDM and the two-photon interference visibility remains unambiguous, in which the high visibility of quantum interference fundamentally reduces quantum bit error rate in quantum-key-distribution system. In this paper, time-bin entangled photon pairs with a raw visibility of 94.3% ± 3.3% are generated in a silicon chip with a channel bandwidth of 0.1 nm, showing a violation of Bell’s inequality by more than three standard deviations, and a fidelity of 0.942 ± 0.02 is obtained by quantum state tomography. Applying variable channel bandwidths, the corresponding two-photon interference visibilities are measured, fitting well with the theoretical model incorporating multiple parameters such as optical loss, dark count probability, and averaged photon-pair number in DWDM channel.

Phase Change Materials (PCMs) have demonstrated tremendous potential as a platform for achieving diverse functionalities in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum, ranging from terahertz to visible frequencies. This comprehensive roadmap reviews the material and device aspects of PCMs, and their diverse applications in active and reconfigurable micro-nanophotonic devices across the electromagnetic spectrum. It discusses various device configurations and optimization techniques, including deep learning-based metasurface design. The integration of PCMs with Photonic Integrated Circuits and advanced electric-driven PCMs are explored. PCMs hold great promise for multifunctional device development, including applications in non-volatile memory, optical data storage, photonics, energy harvesting, biomedical technology, neuromorphic computing, thermal management, and flexible electronics.

Imaging polarimetry based on dielectric metasurface is well-known for its ultra-compactness and high integration. However, previous works suffer from low energy efficiency, limited restrictions on choice of target polarization states, or inability to focus light. Here, by inverse design, we numerically demonstrate a multi-foci metalens-based polarimetry that can simultaneously separate and focus the four free-chosen elliptical polarization states at the wavelength of 10.6 \mu m. Such a full-stokes polarimetry features an average absolute efficiency up to 54.63%, and an average relative error as low as 0.00137%. This spatial-multiplexing-free full stokes polarimetry exceeds the theoretical maximum efficiency of traditional polarization-filtering counterparts, and resolves the restriction faced by the orthogonal polarization-multiplexed method.

High-performance flexible photodetectors are urgently demanded for application in many emerging domains including flexible, wearable, portable, and stretchable optoelectronics. In this work, a highly efficient flexible photodetector made of a Ti3C2Tx MXene/pyramidal thin Si heterostructure is successfully fabricated. Thanks to the remarkable light trapping effect as confirmed by numerical modeling based on finite-element method, the as-constructed detector demonstrates excellent photoresponse performance in a broadband wavelength spectrum. The optimal responsivity, specific detectivity, and response speed reach approximate to 530 mA W-1, approximate to 1.21 x 10(12 )Jones and 30/14 mu s, respectively, at zero bias under near-infrared light illumination. Specifically, the responsivity is greatly enhanced by approximate to 2.65 times, as compared with a planar counterpart. In addition, the light detector can maintain its outstanding photoresponse properties upon 1000 cycles of bending test or at diverse bending radii of curvature, owing to its prominent mechanical flexibility and robust bending endurance. Finally, the capability of monitoring the heart rate of a person in a wideband wavelength spectrum and at various bending radii of curvature is presented. The above results imply the huge potential of the flexible light detector for use in some applications such as wearable health monitoring.

Aside from storing data, memristors can also be used as an entropy source, typically by utilizing the random characteristics of the high resistance state (HRS) or set/reset time delay (TD) of memristors. However, obtaining a reliable high-entropy source remains difficult. In this letter, we designed a novel random number generator (TRNG) circuit that takes full advantage of the memristor’s randomness of reset switching, combining the HRS and TD entropies to achieve higher entropy. The entire random characteristic is derived from two temporal processes: the charging and discharging of a capacitor connected to the memristor. Experiments and simulations illustrate the function and advantages of the TRNG circuit, and a min-entropy of 0.9989 is attained, which is higher and more robust than two independent sources, and which can be further enhanced by the device design itself.