Topologically Protected Plasmonic Bound States in the Continuum.

Experimental realizations of bound states in the continuum (BICs) with strong robustness and advanced maneuverability in optical loss systems remain a long-standing challenge in nanophotonics. Here, we propose and fabricate a paradigm of diatomic metagratings incorporating the Su-Schrieffer-Heeger model into the design of plasmonic nanocavities to demonstrate optical resonators with a continuous "quasi-BICs (qBICs)-BICs-qBICs" transition. These resonators feature a topological band inversion, making high-quality () resonances immune to the perturbation of incident angles and geometrical parameters.

Enhancing the stability of polymer nanostructures via ultrathin oxide coatings for nano-optical device applications.

Polymer nanostructures have drawn tremendous attention due to their wide applications in nanotechnology. However, the morphology of the polymer nanostructures is fragile under harsh conditions such as high-power irradiation and organic-solution environments during the fabrication or the measurement processes, significantly limiting their potential applications. In this work, we propose and demonstrate a simple approach to improve the stability of polymer nanostructures by coating a conformal ultrathin oxide film via atomic-layer deposition.

Periodic planar Fabry-Perot nanocavities with tunable interference colors based on filling density effects.

Structural colors of high performance and economically feasible fabrication are desired in various applications. Herein, we demonstrate that reflective full-color filters based on the interference effect can be realized in periodic Fabry-Perot (F-P) nanocavity arrays of the same thickness. Enabled by simply adjusting the nanocavity size and array period, the resonant wavelengths can be successively tuned in the whole visible light range, which is mainly attributed to the varied effective refractive index introduced by the different filling density of the F-P nanocavity.

Strongly coupled evenly divided disks: a new compact and tunable platform for plasmonic Fano resonances.

Plasmonic artificial molecules are promising platforms for linear and nonlinear optical modulation at various regimes including the visible, infrared and terahertz bands. Fano resonances in plasmonic artificial structures are widely used for controlling spectral lineshapes and tailoring of near-field and far-field optical response. Generation of a strong Fano resonance usually relies on strong plasmon coupling in densely packed plasmonic structures.

Huge field enhancement and high transmittance enabled by terahertz bow-tie aperture arrays: a simulation study.

Sub-wavelength aperture arrays featuring small gaps have an extraordinary significance in enhancing the interactions of terahertz (THz) waves with matters. But it is difficult to obtain large light-substance interaction enhancement and high optical response signal detection capabilities at the same time. Here, we propose a simple terahertz bow-tie aperture arrays structure with a large electric field enhancement factor and high transmittance at the same time.

Kirigami-inspired multiscale patterning of metallic structures via predefined nanotrench templates.

Reliable fabrication of multiscale metallic patterns with precise geometry and size at both the nanoscale and macroscale is of importance for various applications in electronic and optical devices. The existing fabrication processes, which usually involve film deposition in combination with electron-beam patterning, are either time-consuming or offer limited precision. Inspired by the kirigami, an ancient handicraft art of paper cutting, this work demonstrates an electron-beam patterning process for multiscale metallic structures with significantly enhanced efficiency and precision.

3D-Integrated metasurfaces for full-colour holography.

Metasurfaces enable the design of optical elements by engineering the wavefront of light at the subwavelength scale. Due to their ultrathin and compact characteristics, metasurfaces possess great potential to integrate multiple functions in optoelectronic systems for optical device miniaturisation. However, current research based on multiplexing in the 2D plane has not fully utilised the capabilities of metasurfaces for multi-tasking applications.

Stepwise-Nanocavity-Assisted Transmissive Color Filter Array Microprints.

Visible-light color filters using patterned nanostructures have attracted much interest due to their various advantages such as compactness, enhanced stability, and environmental friendliness compared with traditional pigment or dye-based optical filters. While most existing studies are based on planar nanostructures with lateral variation in size, shape, and arrangement, the vertical dimension of structures is a long-ignored degree of freedom for the structural colors. Herein, we demonstrate a synthetic platform for transmissive color filter array by coordinated manipulations between height-varying nanocavities and their lateral filling fractions.

Notched terahertz Bowtie metamaterials with strongly enhanced near-field and narrowed resonance linewidth.

Enhanced near-field and quality factor of resonance are key issues in plasmonic structures. Here, we demonstrate a kind of notched bowtie metamaterials in the terahertz (THz) regime with narrow linewidth and extremely enhanced near field. The notched bowtie is a variation of common bowtie structure created by introducing symmetric notches on the two sides of the triangular metallic structure.

Transmissive structural color filters using vertically coupled aluminum nanohole/nanodisk array with a triangular-lattice.

We demonstrate a configuration to generate transmissive structural colors through triangular-lattice square nanohole arrays in aluminum (Al) film with Al nanodisks on the bottom of the nanoholes. By using a simple nanofabrication process, colors covering the entire visible light with different brightness and saturation are achieved by tuning both the period of arrays and the size of nanoholes. The optical behaviors of the structures are systematically investigated by both experimental and theoretical methods.

Release of an HtrA-Like Protease from the Cell Surface of Thermophilic sp. WF146 via Substrate-Induced Autoprocessing of the N-terminal Membrane Anchor.

High-temperature requirement A (HtrA)-like proteases participate in protein quality control in prokaryotes and eukaryotes by degrading damaged proteins; however, little is known about HtrAs produced by thermophiles. HtrAw is an HtrA-like protease of thermophilic sp. WF146.

Low-voltage-exposure-enabled hydrogen silsesquioxane bilayer-like process for three-dimensional nanofabrication.

We report a bilayer-like electron-beam lithographic process to obtain three-dimensional (3D) nanostructures by using only a single hydrogen silsesquioxane (HSQ) resist layer. The process utilizes the short penetration depth of low-energy (1.5 keV) electron irradiation to first obtain a partially cross-linked HSQ top layer and then uses a high-voltage electron beam (30 keV) to obtain self-aligned undercut (e.

"Sketch and Peel" Lithography for High-Resolution Multiscale Patterning.

We report a unique lithographic process, termed "Sketch and Peel" lithography (SPL), for fast, clean, and reliable patterning of metallic structures from tens of nanometers to submillimeter scale using direct writing technology. The key idea of SPL process is to define structures using their presketched outlines as the templates for subsequent selective peeling of evaporated metallic layer. With reduced exposure area, SPL process enables significantly improved patterning efficiency up to hundreds of times higher and greatly mitigated proximity effect compared to current direct writing strategy.

Reliable fabrication of plasmonic nanostructures without an adhesion layer using dry lift-off.

Lift-off is the most commonly used pattern-transfer method to define lithographic plasmonic metal nanostructures. A typical lift-off process is realized by dissolving patterned resists in solutions, which has the limits of low yield when not using adhesion layers and incompatibility with the fabrication of some specific structures and devices. In this work, we report an alternative 'dry' lift-off process to obtain metallic nanostructures via mechanical stripping by using the advantage of poor adhesion between resists and noble metal films.

Improving the Thermostability and Activity of a Thermophilic Subtilase by Incorporating Structural Elements of Its Psychrophilic Counterpart.

The incorporation of the structural elements of thermostable enzymes into their less stable counterparts is generally used to improve enzyme thermostability. However, the process of engineering enzymes with both high thermostability and high activity remains an important challenge. Here, we report that the thermostability and activity of a thermophilic subtilase were simultaneously improved by incorporating structural elements of a psychrophilic subtilase.