Concentration-Dependent Photoluminescence of Carbon Quantum Dots Useable in LED.

We synthesized carbon quantum dots (CQDs) using a solvothermal method with -phenylenediamine as the carbon and nitrogen source. The sample was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. When we continued the optical characterization of the CQDs, we were surprised to discover that the colors of the synthesized CQDs changed with the dilution of the original solution.

A tunable ultra-broadband and ultra-high sensitivity far-infrared metamaterial absorber based on VO and graphene.

We proposed a far-infrared tunable metamaterial absorber using vanadium dioxide (VO) and graphene as controlling materials. The properties of the absorber are investigated theoretically using the finite-difference time-domain (FDTD) technique. It was found that when the Fermi energy level of graphene is fixed at zero, VO is in the insulated state, and the metasurface exhibits far-infrared broadband absorption performance, with absorptance exceeding 90% in the wavelength range of 12.

A multifunctional switching bidirectional optical absorber based on a titanium nitride metamaterial.

In this paper, a novel type of tunable ultra-wide band and double-narrow band artificial electromagnetic absorption device is studied. This work uses a titanium nitride-titanium-tungsten (TiN-Ti-W) composite ring array, a TiN reflector layer, and a silver-titanium dioxide-silver (Ag-TiO-Ag) three layer composite structure to prepare the absorption layer. The simulation results illustrate that the absorption rate can reach 96.

Metamaterial ultra-wideband solar absorbers based on a multi-layer structure with cross etching.

In this paper, we design a solar absorber based on the SiN-W-Ti-SiO insulator-metal-insulator structure and demonstrate it using the finite difference time domain (FDTD) method. The absorption rate of the absorber consisting of a multi-layer structure with cross etching is over 90% in the bandwidth of 500 nm to 2995 nm with an average absorption rate of 98.3%.

Ultra-efficient diamond plasmonic band-stop filter with enhanced effect.

In this paper, a band-stop filter based on a surface plasmon polariton metal-insulator-metal is designed and studied. The relationship between wavelength and filter transmittance is simulated using the finite difference time domain method and coupled mode theory. Compared with a single-diamond resonator, the minimum transmittances of the double-diamond resonator and double-rectangular resonator at a fixed wavelength are increased by 11.

Dual-Channel Mid-Infrared Toroidal Metasurfaces for Wavefront Modulation and Imaging Applications.

In this paper, we propose a dual-channel mid-infrared toroidal metasurface that consists of split equilateral triangular rings. The electromagnetic responses are analyzed by the finite-difference-time-domain (FDTD) method and temporal coupled-mode theory (TCMT). The results show that one channel of the metasurface is insensitive to the polarization angle of the incident light and temperature, while the other channel is sensitive.

Tunable Dual-Broadband Terahertz Absorber with Vanadium Dioxide Metamaterial.

A dual broadband terahertz bifunction absorber that can be actively tuned is proposed. The optical properties of the absorber were simulated and numerically calculated using the finite-difference time-domain (FDTD) method. The results show that when the conductivity of vanadium dioxide is less than σ0=8.