Nanoscale and ultra-high extinction ratio optical memristive switch based on plasmonic waveguide with square cavity.

A resistive switch effect-based optical memristive switch with an ultra-high extinction ratio and ultra-compact size working at 1550 nm is proposed. The device is composed of a metal-insulator-metal waveguide and a square resonator with active electrodes. The formation and rupture of conductive filaments in the resonant cavity can alter the resonant wavelength, which triggers the state of the optical switch ON or OFF. The numerical results demonstrate that the structure has an ultra-compact size (less than 1 µm) and ultra-high extinction ratio (37 dB). The proposed device is expected to address the problems of high-power consumption and large-scale optical switches and can be adopted in optical switches, optical modulation, optical storage and computing, and large-scale photonic integrated devices.

Analysis and Improvement of a Dual-Core Photonic Crystal Fiber Sensor.

The characteristics of the dual-core photonic crystal fiber (PCF) sensor are studied using the finite element method (FEM), and the structure is improved according to the numerical simulation results. The results show that whether or not the four large air holes far away from the geometry center of the PCF are filled with analyte has no influence on the wavelength sensitivity of the sensor which means those holes can be replaced by small air holes. The wavelength sensitivity can be tuned by adjusting the sizes of the other large air holes which are as for liquid holes. The dynamic detection range of the refractive index (RI) is from 1.33 to 1.51. In particular, high linearity is obtained in the range of 1.44 to 1.51. The sensitivity is as high as 6021 nm/RIU when the liquid holes are the smallest. When liquid holes are tangential with the envelope of first layer air holes, the wavelength sensitivity is 4028 nm/RIU, and the coefficient of determination (R²) is 0.99822 when the RI of the analyte varies from 1.44 to 1.51 which shows that high sensitivity and good linearity are both obtained.

Terahertz wave parametric oscillations at polariton resonance using a MgO:LiNbO3 crystal.

Terahertz wave (THz-wave) parametric oscillations with a noncollinear phase-matching scheme at polariton resonance using a MgO:LiNbO3 crystal with a surface-emitted configuration are investigated. We investigate frequency tuning characteristics of a THz-wave via varying the wavelength of the pump wave and phase-matching angle. The effective parametric gain length under the noncollinear phase-matching condition is calculated. Parametric gain and absorption characteristics of a THz-wave in the vicinity of polariton resonances are analyzed.

Engineering VOx structure by integrating oxygen vacancies for improved zinc-ion storage based on cation-doping regulation with electric density.

Aqueous zinc-ion batteries (ZIBs) have attracted enormous attention for future energy-storage devices owing to their high theoretical capacity and environmental friendliness. However, obtaining cathodes with a high specific capacity and fast reaction kinetics remains a huge challenge. Herein, Cu-VOx material with a thin sheet microsphere structure composed of nanoparticles was prepared by a simple hydrothermal reaction, which improved reaction kinetics and specific capacity. Pre-embedding Cu2+ into V2O5 to introduce abundant oxygen vacancies extended the interlayer distance to 1.16 nm, weakened the effect of the V-O bonds, and improved the electrical conductivity and structural stability. At the same time, the influence of different valence metal ions (M = K+, Cu2+, Fe3+, Sn4+, Nb5+, and W6+) pre-embedded in V2O5 was studied. Benefiting from a large interlayer spacing, high electrical conductivity, and excellent structural stability, the Cu-VOx electrode demonstrated a high specific capacity of 455.9 mA h g-1 at 0.1 A g-1. Importantly, when the current density was increased to 6 A g-1, the Cu-VOx electrode still achieved a high specific capacity of 178.8 mA h g-1 and maintained a high capacity retention of 76.5% over 2000 cycles.

Anchoring carbon layers and oxygen vacancies endow WO3-x /C electrode with high specific capacity and rate performance for supercapacitors.

Herein, novel hierarchical carbon layer-anchored WO3-x /C ultra-long nanowires were developed via a facile solvent-thermal treatment and a subsequent rapid carbonization process. The inner anchored carbon layers and abundant oxygen vacancies endowed the WO3-x /C nanowire electrode with high conductivity, as measured with a single nanowire, which greatly enhanced the redox reaction active sites and rate performance. Surprisingly, the WO3-x /C electrode exhibited outstanding specific capacitance of 1032.16 F g-1 at the current density of 1 A g-1 in a 2 M H2SO4 electrolyte and maintained the specific capacitance of 660 F g-1 when the current density increased to 50 A g-1. Significantly, the constructed WO3-x /C//WO3-x /C symmetric supercapacitors achieved specific capacitance of 243.84 F g-1 at the current density of 0.5 A g-1 and maintained the capacitance retention of 94.29% after 5000 charging/discharging cycles at the current density of 4 A g-1. These excellent electrochemical performances resulted from the fascinating structure of the WO3-x /C nanowires, showing a great potential for future energy storage applications.