Energy Dissipation and Asymmetric Excitation in Hybrid Waveguides for Routing and Coloring

Excitation of out-of-plane lattice plasmons in dislocated nanostructures through near-field coupling

Out-of-plane lattice plasmons (OLPs) show great potential in realizing high-quality factors due to the strong interparticle coupling. However, the strict conditions of oblique incidence bring challenges to experimental observation. This Letter proposes a new, to the best of our knowledge, mechanism to generate OLPs: through near-field coupling. Notably, with specially designed nanostructure dislocation, the strongest OLP can be achieved at normal incidence. The direction of energy flux of the OLPs is mainly determined by the wave vectors of Rayleigh anomalies. We further found that the OLP exhibits symmetry-protected bound states in the continuum characteristic, which explains the failure of previously reported symmetric structures to excite OLPs at normal incidence. Our work extends the understanding of the OLP and brings benefit to promote the flexible design of functional plasmonic devices.

Temperature and pressure sensitive ionic conductive triple-network hydrogel for high-durability dual signal sensors

In this work, the fabrication of strengthened triple network hydrogels was successfully achieved based on in-situ polymerization of polyacrylamide by combining both chemical and physical cross-linking methods. The ion conductive phase of lithium chloride (LiCl) and solvent in the hydrogel were regulated through soaking solution. The pressure and temperature sensing behavior and durability of the hydrogel were investigated. The hydrogel containing 1 mol/L LiCl and 30 %v/v glycerol displayed a pressure sensitivity of 4.16 kPa^-1 and a temperature sensitivity of 2.04 %/^oC ranging from 20 to 50 °C. The durability results reveal that the hydrogel could maintain water retention rate of 69 % after 20 days of ageing. The presence of LiCl disrupted the interactions among water molecules and made it possible for the hydrogel to respond to changes in environment humidity. The dual signal testing revealed that the delay of temperature response over time (about 100 s) is much different from the rapidity of pressure response (in 0.5 s). This leads to the obvious separation of the temperature-pressure dual signal output. The assembled hydrogel sensor was further applied to monitor human motion and skin temperature. The signals can be distinguished by different resistance variation values and curve shapes in the typical temperature-pressure dual signal performance of human breathing. This demonstrates that this ion conductive hydrogel has the potential for application in flexible sensors and human-machine interfaces.

Microstructure, grain and nanowire growth during selective laser melting of Ag-Cu/diamond composites

Selective laser melting (SLM) technique is a viable alternative to fabricating metal matrix composites (MMCs) with controllable structures; however, its implementation remains challenging because of the unpredicted defects arising from the reinforcement. This study primarily examined the microstructural evolution and grain growth in the Ag-Cu/diamond composites at the molten pool scale during the SLM process via a thermodynamic analysis. The feasibility of manufacturing Ag-Cu/diamond composites was verified using several processing parameters. Moreover, the influence of energy density on the microstructures and grain growth was also demonstrated theoretically and experimentally. The formation of different kinds of grain morphologies in the molten pool was ascribed to the temperature gradient and cooling rate, corresponding to the direction and size of grain growth. The generation of Ag-Cu nanowires at the grain boundaries was firstly found in the SLM technique, which was related to the pressure stress generated by the high cooling rate of SLM. This work hopefully opens new paths for the applications of high-performance Ag-Cu/diamond MMCs in various application fields. It also provides new possibilities for the controllable manufacturing of Ag nanowires during SLM.

Synthesis of flexible Co nanowires from bulk precursors

This work reports a method of producing flexible cobalt nanowires (NWs) directly from the chemical conversion of bulk precursors at room temperature. Chemical reduction of Li₆CoCl₈ produces a nanocomposite of Co and LiCl, of which the salt is subsequently removed. The dilute concentration of Co in the precursor combined with the anisotropic crystal structure of the hcp phase leads to 1D growth in the absence of any templates or additives. The Co NWs are shown to have high saturation magnetization (130.6 emu g⁻¹). Our understanding of the NW formation mechanism points to new directions of scalable nanostructure generation.

This work reports a method of producing flexible cobalt nanowires (NWs) directly from the chemical conversion of bulk precursors at room temperature.

Nanosized FeS/ZnS heterojunctions derived using zeolitic imidazolate Framework-8 (ZIF-8) for pH-universal oxygen reduction and High-efficiency Zn-air battery

Low-cost, stable, and highly active electrocatalysts for oxygen reduction reaction (ORR), especially for pH-universal ORR, are vital for developing numerous renewable energy devices. Herein, a hierarchical N, S-codoped porous carbon-based catalyst (ZFP-800) coupled with abundant FeS/ZnS heterojunctions was facilely prepared via direct pyrolysis of a Ferrocene-crosslinked pyrrole hydrogel composited with zeolitic imidazolate framework-8 (ZIF-8) templates. Compared with the heterojunction-free catalytic activity, the ZFP-800 catalytic activity was significantly higher in pH-universal ranges. Moreover, the ZFP-800 exhibited competitive ORR performance to commercial Pt/C (20%) in various electrolytes, in terms of onset (E_onset), half-wave potentials (E_1/2), limiting current density (J_L), durability, and methanol immunity. For instance, it exhibited super ORR catalytic activity on E_onset and E_1/2, and exceeded that of the benchmark Pt/C in both the alkaline and neutral media. Furthermore, the application of ZFP-800 as a cathode catalyst in a home-made Zn-air battery demonstrated its operation capability in ambient conditions with a competitive performance on the specific energy density (828 mA·h·g_Zn^-1), maximum discharge power density (205.6 mW·cm^-2), rate performance, and the long-term stability (188 h at 5 mA·cm^-2). This study can facilitate the development of advanced heterojunction-based materials for renewable energy applications.

The impact of fluence dependent proton ion irradiation on the structural and optical properties of Bi5In30Se65 thin films for nonlinear optical devices

The influence of 30 keV proton ion irradiation on the surface morphology, surface topography and optical properties of Bi5In30Se65 thin films.

Nanostructured hybrid plasmonic waveguide in a slot structure for high-performance light transmission

Squeezing light to nanoscale is the most vital capacity of nanophotonic circuits processing on-chip optical signals that allows to significantly enhance light-matter interaction by stimulating various nonlinear optical effects. It is well known that plasmon can offer an unrivaled concentration of optical energy beyond the optical diffraction limit. However, the progress of plasmonic technology is mainly hindered by its ohmic losses, thus leading to the difficulty in building large-area photonic integrated circuits. To significantly increase the propagation distance of light, we develop a new waveguide structure operating at the telecommunication wavelength of 1,550 nm. It consists of a nanostructured hybrid plasmonic waveguide embedded in a high-index-contrast slot waveguide. We capitalize on the strong mode confinement of the slot waveguide and reduce mode areas with the nanostructured hybrid plasmonic configuration while maintaining extremely low ohmic losses using a nanoscale metal strip. The proposed design achieves a record propagation distance of 1,115 µm while comparing with that of other designs at a mode area of the order of 10^-5A₀ (A₀ is the diffraction-limited area). The mode characterization considering fabrication imperfections and spectral responses show the robustness and broadband operation range of the proposed waveguide. Moreover, we also investigated the crosstalk to assess the density of integration. The proposed design paves the way for building nanophotonic circuits and optoelectronic devices that require strong light-matter interaction.