• Material-structure integrated design for ultra-broadband microwave metamaterial absorber

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: We propose herein a method of material-structure integrated design for broadband absorption of dielectric metamaterial, which is achieved by combination of genetic algorithm and simulation platform. A multi-layered metamaterial absorber with an ultra-broadband absorption from 5.3 to 18 GHz (a relative bandwidth of as high as 109%) is realized numerically and experimentally. In addition, simulated results demonstrate the proposed metamaterial exhibits good incident angle and polarization tolerance, which also are significant criteria for practical applications. By investigating the working principle with theoretical calculation and numerical simulation, it can be found that merging of multiple resonance modes encompassing quarter-wavelength interference cancellation, spoof surface plasmon polariton mode, dielectric resonance mode and grating mode is responsible for a remarkable ultra-broadband absorption. Analysis of respective contribution of material and structure indicates that either of them plays an indispensable role in activating different resonance modes, and symphony of material and structure is essential to afford desirable target performance. The material-structure integrated design philosophy highlights the superiority of coupling material and structure and provides an effective comprehensive optimization strategy for dielectric metamaterials.

  • Impact of Halogen Bonds on Protein-Peptide Binding and Protein Structural Stability Revealed by Computational Approaches

    分类: 药物科学 >> 药物设计 提交时间: 2024-04-10

    摘要: Halogen bonds (XBs) are essential non-covalent interactions in molecular recognition and drug design. Current studies on XBs in drug design mainly focus on the interactions between halogenated ligands and target proteins, lacking a systematic study on naturally existing and artificially prepared halogenated residue XBs (hr_XBs) and their characteristics. Here, we conducted a computational study on the potential hr_XBs in proteins/peptides using database searching, quantum mechanics calculations, and molecular dynamics simulations. XBs at protein-peptide interaction interfaces are found to enhance their binding affinity. Additionally, the formation of intramolecular XBs (intra_XBs) within proteins may significantly contribute to the structural stability of structurally flexible proteins, while having a minor impact on proteins with inherently high structural rigidity. Impressively, introducing halogens without the formation of intra_XBs may lead to a decrease in protein structural stability. This study enriches our comprehension of the roles and effects of halogenated residue XBs in biological systems.

  • Silicon carbide for integrated photonics

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: The recent progress in chip-scale integrated photonics has stimulated the rapid development of material platforms with desired optical properties. Among the different material platforms that are currently investigated, the third-generation semiconductor, silicon carbide (SiC), offers the broadest range of functionalities, including wide bandgap, high optical nonlinearities, high refractive index, and CMOS-compatible device fabrication process. Here, we provide an overview of SiC-based integrated photonics, presenting the latest progress on investigating its basic optical and optoelectronic properties, as well as the recent developments in the fabrication of several typical approaches for light confinement structures that form the basic building blocks for low-loss, high functional and industry-compatible integrated photonic platform. Moreover, recent works employing SiC as optically-readable spin hosts for quantum information applications are also summarized and discussed. As a still-developing integrated photonic platform, the prospects and challenges of SiC material platform in the field of integrated photonics are also discussed, followed by potential solutions.

  • D3Rings: A fast and accurate method for ring system identification and deep generation of drug-like cyclic compounds

    分类: 药物科学 >> 药物设计 提交时间: 2024-02-06

    摘要: Continuous exploration of the chemical space of molecules to find ligands with high affinity and specificity for specific targets is an important topic in drug discovery. A focus on cyclic compounds, particularly natural compounds with diverse scaffolds, provides important insights into novel molecular structures for drug design. However, the complexity of their ring structures has hindered the applicability of widely accepted methods and software for the systematic identification and classification of cyclic compounds. Herein, we successfully developed a new method, D3Rings, to identify acyclic, monocyclic, spiro ring, fused and bridged ring, and cage ring compounds as well as macrocyclic compounds. By using D3Rings, we completed the statistics of cyclic compounds in 3 different databases, e.g., ChEMBL, DrugBank, and COCONUT. The results demonstrated the richness of ring structures in natural products, especially spiro, macrocycles, fused and bridged rings. Based on this, three deep generative models, namely VAE, AAE, and CharRNN, were trained and used to construct two datasets similar to DrugBank and COCONUT but 10 times larger than them. The enlarged datasets were then used to explore the molecular chemical space, focusing on complex ring structures, for novel drug discovery and development. Docking experiments with the newly generated COCONUT-like dataset against three SARS-CoV-2 target proteins revealed that an expanded compound database improves molecular docking results. Cyclic structures were exhibited the best docking scores among the top-ranked docking molecules. These results suggest the importance of exploring the chemical space of structurally novel cyclic compounds and continuous expansion of the library of drug-like compounds to facilitate the discovery of potent ligands with high binding affinity to specific targets. D3Rings is now freely available at http://www.d3pharma.com/D3Rings/.

  • Hybrid integration of deterministic quantum dots-based single-photon sources with CMOS-compatible silicon carbide photonics

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: Thin film 4H-silicon carbide (4H-SiC) is emerging as a contender for realizing large-scale optical quantum circuits due to its high CMOS technology compatibility and large optical nonlinearities. Though, challenges remain in producing wafer-scale 4H-SiC thin film on insulator (4H-SiCOI) for dense integration of photonic circuits, and in efficient coupling of deterministic quantum emitters that are essential for scalable quantum photonics. Here we demonstrate hybrid integration of self-assembled InGaAs quantum dots (QDs) based single-photon sources (SPSs) with wafer-scale 4H-SiC photonic chips prepared by ion slicing technique. By designing a bilayer vertical coupler, we realize generation and highly efficient routing of single-photon emission in the hybrid quantum photonic chip. Furthermore, we realize a chip-integrated beamsplitter operation for triggered single photons through fabricating a 1x2 multi-mode interferometer (MMI) with a symmetric power splitting ratio of 50:50. The successful demonstration of heterogeneously integrating QDs-based SPSs on 4H-SiC photonic chip prepared by ion slicing technique constitutes an important step toward CMOS-compatible, fast reconfigurable quantum photonic circuits with deterministic SPSs.

  • An Ultrahigh-Q Microresonator on 4H-silicon-carbide-on-insulator Platform for Multiple Harmonics, Cascaded Raman Lasing and Kerr Comb Generations

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: The realization of ultrahigh quality (Q) resonators regardless of the underpinning material platforms has been a ceaseless pursuit, because the high Q resonators provide an extreme environment of storage of light to enable observations of many unconventional nonlinear optical phenomenon with high efficiencies. Here, we demonstrate an ultra-high Q factor (7.1*10^6) microresonator on the 4H-silicon-carbide-on-insulator (4H-SiCOI) platform in which both \c{hi}^(2) and \c{hi}^(3) nonlinear processes of high efficiencies have been generated. Broadband frequency conversions, including second-, third-, fourth-harmonic generation were observed. Cascaded Raman lasing was demonstrated in the SiC microresonator for the first time to the best of our knowledge. Broadband Kerr frequency combs covering from 1300 to 1700 nm were achieved using a dispersion-engineered SiC microresonator. Our demonstration is a significant milestone in the development of SiC photonic integrated devices.