Dynamically Temperature-Voltage Controlled Multifunctional Device Based on VO and Graphene Hybrid Metamaterials: Perfect Absorber and Highly Efficient Polarization Converter.

Vanadium dioxide (VO) is a temperature phase change material that has metallic properties at high temperatures and insulation properties at room temperature. In this article, a novel device has been designed based on the dielectric metasurface consisting of VO and graphene array, which can achieve multiple functions by adjusting temperature and voltage. When the temperature is high (340 K), the device is in the absorption state and its absorptivity can be dynamically controlled by changing the temperature.

Negative Differential Conductance Assisted by Optical Fields in a Single Quantum Dot with Ferromagnetic Electrodes.

In a single quantum dot (QD) system connected with ferromagnetic electrodes, the electron transport properties, assisted by the thermal and Fock state optical fields, are theoretically studied by the Keldysh nonequilibrium Green's function approach. The results show that the evolution properties of the density of state and tunneling current assisted by the Fock state optical field, are quite different from those of the thermal state. The photon sideband shift decreases monotonously with the increase in the electron-photon coupling strength for the case of the thermal state, while the shift is oscillatory for the case of the Fock state.

Full Counting Statistics of Electrons through Interaction of the Single Quantum Dot System with the Optical Field.

In this paper, using the particle-number-resolved master equation, the properties of full counting statistics (FCS) are investigated for a single quantum dot (QD) system interacting with optical fields in the thermal state, Fock state, coherent state, and coherent state with random phase. In these diverse quantum states of optical fields, average tunneling currents have different step shoulder heights at a lower bias voltage with the same light intensity, and a staircase-shaped current can be induced unexpectedly in vacuum state optical field. The characteristics of the Fano factor and skewness in the coherent state differ from those in all of the other cases.

Analogue of electromagnetically induced absorption with double absorption windows in a plasmonic system.

We report the observation of an analog of double electromagnetically induced absorption (EIA) in a plasmonic system consisting of two disk resonators side-coupled to a discrete metal-insulator-metal (MIM) waveguide. The finite-difference time-domain (FDTD) simulation calculations show that two absorption windows are obtained and can be easily tuned by adjusting the parameters of the two resonance cavities. The consistence between the coupled-model theory and FDTD simulation results verify the feasibility of the proposed system.

Active plasmonic band-stop filters based on graphene metamaterial at THz wavelengths.

Active plasmonic band-stop filters based on single- and double-layer doped graphene metamaterials at the THz wavelengths are proposed and investigated numerically by using the finite-difference time-domain (FDTD) method. The metamaterial unit cell structure is composed of two parallel graphene nanoscale ribbons. Simulated results exhibit that significant resonance wavelength shifts can be achieved with a slight variation of the doping concentration of the graphene ribbons.

Double plasmonic nanodisks design for electromagnetically induced transparency and slow light.

An analog of plasmonic system for electromagnetically induced transparency (EIT), in which a small nanodisk with a big side-coupled-nanodisk is directly coupled to the metal-insulator -metal (MIM) waveguide, has been proposed and investigated theoretically and numerically. When the resonant frequencies of the two nanodisks differ not too much, a powerful EIT-like effect can be obtained, and the transparency window can be easily tuned by adjusting the radii of the two nanodisks. The plasmonic device can be used as a high-performance EIT-like filter with transmission over 80% and full width at half-maximum (FWHM) less than 30nm, besides, the novel structure shows a high group index over 355.

Asymmetric band-pass plasmonic nanodisk filter with mode inhibition and spectrally splitting capabilities.

A compact wavelength band-pass filter based on metal-insulator-metal (MIM) nanodisk cavity is proposed and numerically investigated by using Finite-Difference Time-Domain (FDTD) simulations. It is found that the transmission characteristics of the filter can be easily adjusted by changing the geometrical parameters of the radius of the nanodisk and coupling distance between the nanodisk and waveguide. By extending the length of input/output waveguides, the filter shows the resonant mode inhibition function.

Plasmonic filters and optical directional couplers based on wide Metal-Insulator-Metal structure.

The wide Metal-Insulator-Metal (WMIM) structure is proposed and its characteristics are analyzed numerically using finite-difference time-domain (FDTD) method. Simulations show that power can be periodically transferred between its two Metal-Insulator (MI) interfaces while power is injected asymmetrically. Novel plasmonic filters and optical directional couplers (ODCs) based on WMIM structure are proposed, which work similarly as traditional dielectric devices.