Bi-La composite oxide was prepared by thermal decomposition of molecular precursor of BiLa(dtpa)(NO 3 )•3.5H 2 O (dtpa=Diethylene triaminepentaacetic). The effect of calcinated temperature on structure was discussed by X-ray powder diffraction, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic performance of samples prepared was discussed through the degradation of methyl orange. The results show that Bi-La composite oxide prepared at 500°C exhibits the best photocatalytic activity for the degradation of methyl orange (20mg/L) and the optimum amount of photocatalyst is 1.0 g/L.
Abstract Photonic elements have greater information‐carrying capabilities compared to electronic components, making the development of high‐speed, chip‐integrated optical communication devices crucial for addressing interconnect bottlenecks in high‐speed computing systems. Significant progress has been made in studying light sources and their transmission. Despite these advancements, achieving a satisfactory integration of photonic circuits with both light source and optical waveguide functions has remained a challenge. Here, a silver nanowire (AgNW) waveguide‐integrated light source is demonstrated driven by alternating current (AC) voltage. AgNW functions as both the electrode and waveguide to simplify the device structure, and the 2D transition metal dichalcogenides (TMDs) monolayer acts as the gain media in device. The electroluminescence (EL) can be tunably modulated via adjusting the frequency and voltage of the AC in this device, and it is also successfully coupled into the waveguide with its transmission distance up to 25 µm. The experiments of electroluminescence and waveguide transmission of different materials and their interlayer excitons have made a preliminary exploration of multiple wavelength transmission. It provides a new research platform forward in the development of chip‐integrated optical communication devices, thereby hopefully addressing the interconnect bottleneck and unlocking the potential for enhanced performance and efficiency in high‐speed computing systems.
Abstract Indium selenide (InSe) has attracted tremendous research interest due to its excellent optical and electronic properties. The direct bandgap of bulk InSe promises efficient carrier recombination in the near‐infrared (NIR) spectral range, holding great potential for NIR‐based optoelectronic device applications. However, the lowest energy transition in InSe involves out‐of‐plane optical dipoles, with resulting photoluminescence (PL) transmitted mainly along the layer plane. This limits both optical excitation and detection efficiency along the surface normal for practical device operation. To circumvent this issue, here, bulk InSe flake is coupled with circular Bragg grating (CBG) fabricated on silicon substrate by focused ion beam milling. A maximal 60‐fold PL enhancement is achieved, with Purcell effect‐facilitated carrier recombination and improved light out‐coupling via CBG contributing jointly. The same device architecture is further demonstrated to boost the second harmonic generation by a factor of 34. The results provide an effective way to enhance the optical performance of III–VI layered nanomaterials for both linear and nonlinear optoelectronic device applications.
A hetrobimentallic complex of Zn[Bi(edta)] 2 •8H 2 O was synthesized under hydrothermal condition and characterized by means of X-ray single crystal diffraction, element analysis, FT-IR spectra and thermal analysis. The complex is monoclinic, space group C2/c with a =2.3532(8) nm, b=0.8675(3) nm, c=1.6116(6) nm, β=98.114(6) °, V=3.2569(19) nm3, Z=4，Dc= 2.455 g•cm －3 ，μ= 11.615mm－1. Bridging edta4－ anions between Bi(III) atoms result into infinite 1D zigzag chain. [Bi(edta)]－anions and [Zn(H 2 O) 6 ] 2+ cations are bonded through hydrogen bonds to form network structure. The thermal decomposition of the complex proceeds dehydration, pyrolysis of ligand, and decomposition of salt, and the final residue is inorganic oxide. The thermodynamic parameters ( ΔH、ΔG and ΔS) and kinetic parameters (activation energy Ea and the pre-exponential factor A) for the pyrolysis of ligand have been calculated.
High-index semiconductor nanoantennae represent a powerful platform for nonlinear photon generation. Devices with reduced footprints are pivotal for higher integration capacity and energy efficiency in photonic integrated circuitry (PIC). Here, we report on a deep subwavelength nonlinear antenna based on dilute nitride GaNP nanowires (NWs), whose second harmonic generation (SHG) shows a 5-fold increase by incorporating ∼0.45% of nitrogen (N), in comparison with GaP counterpart. Further integrating with a gold (Au) thin film-based hybrid cavity achieves a significantly boosted SHG output by a factor of ∼380, with a nonlinear conversion efficiency up to 9.4 × 10–6 W–1. In addition, high-density zinc blende (ZB) twin phases were found to tailor the nonlinear radiation profile via dipolar interference, resulting in a highly symmetric polarimetric pattern well-suited for coupling with polarization nano-optics. Our results manifest dilute nitride nanoantenna as promising building blocks for future chip-based nonlinear photonic technology.
Dark exciton states show great potential in condensed matter physics and optoelectronics because of their long lifetime and rich distribution in band structures. Therefore, they can theoretically serve as efficient energy reservoirs, providing a platform for future applications. However, their optical-transition-forbidden nature severely limits their experimental exploration and hinders their current application. Here, we demonstrate a universal dark state nonlinear energy transfer (ET) mechanism in monolayer WS2/CsPbBr3 van der Waals heterostructures under two-photon excitation, which successfully utilizes the enormous energy reserved in the dark exciton state of CsPbBr3 to significantly improve the photoelectric performance of monolayer WS2. We first propose the scenario of resonant ET between the dark state of CsPbBr3 and WS2, and then reveal that this is a typical Förster resonant ET and belongs to the 2D-2D category. Interestingly, the dark state ET in CsPbBr3 is identified as a long-range donor–bridge–acceptor hopping mode, with a potential distance exceeding 200 nm. Finally, we successfully achieve nearly an order of magnitude enhancement in the near-infrared detection performance of monolayer WS2. Our results enrich the theory of dark exciton states and ET, and they provide a way of using dark exciton states for future practical applications.
Summary Due to the proliferation of the wireless communication technologies, we are now in the era of ubiquitous computing. People can enjoy services almost in any time and any location based on the mobile intelligent devices. Meanwhile, more and more personal information are transmitted through the network. To protect these sensitive information, authentication and privacy protection are primary concerns in ubiquitous communication environments. However, traditional physical‐based biometric authentication scheme usually requires explicit cooperation of the user, which is inconvenient to the users. In order to solve this problem, a behavior biometric authentication protocol with privacy protection is designed using matrix multiplication and homomorphic encryption for ubiquitous communication environments. The correctness, security, and privacy protection properties are proved with security analysis. Performance evaluation shows that our protocol achieves stronger security and higher communication efficiency compared with other related protocols, which makes it very suitable for ubiquitous communication environments because communication consumes much more energy than computation does in mobile communication.
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