Left‐handed metamaterials (LHMs) composed of random dendritic cells demonstrate a multi‐band resonance and negative refractive index. A nano‐assembly approach is established to fabricate optical LHMs. Random nanostructures of silver dendritic cells are prepared and further fabricated into a sandwich‐like structure with a dielectric medium. The dentritic nano‐assembled configuration reveals a multi‐band resonance and a high intensity of the pass‐band at infrared frequencies, and can be facilely and cheaply prepared on a large‐scale of effective area.
We experimentally demonstrate the trapped rainbow in tapered left-handed heterostructures (LHHs) at visible frequencies. The employed left-handed metamaterials (LHMs) are isotropic with the size of hundreds of square millimeter. Specifically, the LHMs sample at visible frequencies has a broad spectral range and low loss, making it an intrinsic optical response for the LHHs. It is found that the frequency components of the wave packet separate at positions with different guide thicknesses only if the inclination of tapered LHHs is greater than zero and smaller than the critical value.
In this work, the optical metamaterials based on silver dendritic cells are prepared by electrochemical deposition, and its transmission and focusing behaviors are investigated. The experimental results show that the optical metamaterials reveal a multiple pass-band transmission spectrum and a prominent focusing effect at the wavelength corresponding to the maximum transmission coefficient. Two optical metamaterial samples are combined into a tapered optical waveguide, and the spectra of transmitted light at the surface of the tapered optical waveguide is measured by using the fiber spectrometer along the light propagation direction. The results demonstrate that each frequency component of the wave packet is stopped at a different waveguide thickness, leading to the spatial separation of its spectrum. The spatial separation of spectrum can be effectively tuned by adjusting the inclination of the tapered optical waveguide, which can be used for storing photons and slow-light research. metamaterial, silver dendritic structure, tapered optical waveguide, spatial separation of spectrum
Citation:Cheng X C, Fu Q H, Zhao X P. Spatial separation of spectrum inside the tapered metamaterial optical waveguide.
The friction and wear properties of an Al6061 alloy reinforced with carbon fibers (CF) modified with Cu-Ni bimetallic layers were researched. Cu-Ni double layers were applied to the CF by electroless plating and Al6061-matrix composites were prepared by powder metallurgy technology. The metal-CF/Al interfaces and post-dry-wear-testing wear loss weights, friction coefficients, worn surfaces, and wear debris were characterized. After T6 heat treatment, the interfacial bonding mechanism of Cu-Ni-CF changed from mechanical bonding to diffusion bonding and showed improved interfacial bonding strength because the Cu transition layer reduced the fiber damage caused by Ni diffusion. The metal–CF interfacial bonding strongly influenced the composite’s tribological properties. Compared to the Ni-CF/Al and Cu-CF/Al composites, the Cu-Ni-CF/Al composite showed the highest hardness, the lowest friction coefficient and wear rate, and the best load-carrying capacity. The wear mechanisms of Cu-Ni-CF/Al composite are mainly slight abrasive wear and adhesive wear.
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