A novel planar plasmonic metamaterial for electromagnetically induced transparency and slow light characteristic is presented in this paper, which consists of nanoring and nanorod compound structures. Two bright modes in the metamaterial are induced by the electric dipole resonance inside nanoring and nanorod, respectively. The coupling between two bright modes introduces transparency window and large group index. By adjusting the geometric parameters of metamaterial structure, the transmittance of EIT window at 385 THz is about 60%, and the corresponding group index and Q factor can reach up to 1.2 × 10³ and 97, respectively, which has an important application in slow-light device, active plasmonic switch, SERS and optical sensing.

The light-emitting properties of Ge nanocrystals on an Si(100) matrix prepared by pulsed laser deposition (PLD) and in situ rapid thermal annealing (RTA) were studied. The photoluminescence (PL) intensity becomes stronger and the FWHM decreases from 100 to 50 meV when the annealing temperature varies from 300 to 600 °C, reflecting that the as-deposited amorphous Ge has been effectively crystallized by high temperature. Also, the PL peak significantly shifts from 0.786 to 0.732 eV and the FWHM of the peaks increases from 30 to 70 meV as deposition time increases from 30 s to 8 min, indicating that the PL of the Ge nanocrystals has a large quantum size effect. In addition, the PL peaks increase initially and then decrease with increasing reversed bias voltage, which is attributed to the tunnelling effect of the carriers.

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The interest in investigating hollow core–shell nanostructures was stimulated by their intrinsic advantage in light absorption and photocarrier separation for promising applications in photoelectrochemical devices. Here, SnO2@TiO2 core–shell hierarchical tubular structure was designed and prepared via a low-temperature solution route using carbon nanofibers as templates. The heterostructure consists of SnO2 nanotubes and TiO2 nanocones, which facilities photocarrier separation and transport by built-in electric field at their interface, and direct transport path served by SnO2 nanotubes. The large specific surface area was also believed to contribute to improve performance by providing more active sites for chemical reactions. After assembling into a photoelectrochemical-type ultraviolet photodetector, the detector exhibits a high short-circuit photocurrent density of 870 μA cm–2 under ultraviolet illumination (λ = 365 nm) of 35 mW cm–2 without bias voltage. The photosensitivity can reach up to 3781, and the feature response time was in microseconds, 33 ms for rise process and 13 ms for decay process. It is believed that this structure with combined advantageous features is extendable to other photoelectrochemical cases, such as dye-sensitized solar cells and artificial photosynthesis.