ANGLE-INSENSITIVE MICROWAVE METAMATERIAL ABSORBERS OPERATING AT TRANSMISSION MODE

Metamaterial absorbers with the resonator/dielectric/metallic-mirror conventional design are often angle-dependent and completely reflective outside the absorption band. Here we propose a novel solution to achieve an angle-insensitive bidirectional absorber operating at the transmission mode using a simple metamaterial system. The proposed system is composed of two symmetric disk-pair layers, called the disk-pair dimer, that exhibit two identical but coupled magnetic resonances at the same frequency. This unique design allows to absorb the electromagnetic energy at the transmission mode, which is rarely achievable in conventional ones. By optimizing the coupling strength between two disk-pair layers, the total absorptivity can be enhanced up to 90%.

A Triple-Band Hybridization Coherent Perfect Absorber Based on Graphene Metamaterial

In this paper, a triple-band hybridization coherent perfect absorber based on graphene metamaterial is proposed, which consists of graphene concentric nanorings with different sizes and a metallic mirror separated by SiO2 layer. Based on the finite-difference time-domain (FDTD) solution, triple-band coherent perfect absorption is achieved at frequencies from 0.6 THz to 1.8 THz, which results from the surface plasmon resonance hybridization. The wavelength of the absorption peak can be rapidly changed by varying the Fermi level of graphene. Most importantly, the wavelength of the absorption peak can be independently tuned by varying the Fermi level of the single graphene nanoring. Moreover, the triple hybridization perfect absorber is angle-insensitive because of the perfect symmetry structure of the graphene nanorings. Therefore, our results may widely inspire optoelectronic and micro-nano applications, such as cloaking, tunable sensor, etc.

A single bottom facet outperforms random multifacets in a nanoparticle-on-metallic-mirror system

Highly efficient nanoparticle-on-metallic-mirror (NPOM) systems with a large gap size exhibiting good plasmonic enhancement are desirable for numerous practical applications.

Scalable electrochromic nanopixels using plasmonics

Plasmonic metasurfaces are a promising route for flat panel display applications due to their full color gamut and high spatial resolution. However, this plasmonic coloration cannot be readily tuned and requires expensive lithographic techniques. Here, we present scalable electrically driven color-changing metasurfaces constructed using a bottom-up solution process that controls the crucial plasmonic gaps and fills them with an active medium. Electrochromic nanoparticles are coated onto a metallic mirror, providing the smallest-area active plasmonic pixels to date. These nanopixels show strong scattering colors and are electrically tunable across >100-nm wavelength ranges. Their bistable behavior (with persistence times exceeding hundreds of seconds) and ultralow energy consumption (9 fJ per pixel) offer vivid, uniform, nonfading color that can be tuned at high refresh rates (>50 Hz) and optical contrast (>50%). These dynamics scale from the single nanoparticle level to multicentimeter scale films in subwavelength thickness devices, which are a hundredfold thinner than current displays.