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Dielectric polymer-based composites have demonstrated enormous promise in the applications of electrostatic film capacitors due to their exceptional insulating characteristics. However, the achievement of great energy-storage density (U e) is always difficult in linear dielectric polymer-based composites for operation at weak field strength due to the low permittivity (ϵ r) and electric displacement difference (D max − D rem) values. Here, a tri-layered configuration of multicomponent polymeric films is proposed. The outer layers of the tri-layered composite are linear dielectric polymethyl methacrylate (PMMA), and the inner layer is a nonlinear polymer incorporating a low number of polydopamine-modified barium titanate particles (BT@PDA). An increased ϵ r of 8.9@1 kHz is achieved in the designed composite featuring only 2 wt% BT@PDA fillers, equivalent to 234% of the PMMA (∼3.8@1 kHz) matrix. An improved U e of 9.3 J cm−3 at 340 MV m−1 is endowed in the designed film, implying an enormous ∼343% increment of the energy storage compared to the benchmark biaxially oriented polypropylene (∼2.1 J cm−3 at 300 MV m−1). All these advantages present a practical strategy for supplying linear dielectric polymer-based composites with anticipative capacitive energy-storage properties for operation at weak field strengths.

The third-order nonlinear processes in nanophotonic devices may have great potentials for developing ultra-compact nonlinear optical sources, ultrafast optical switches and modulators, etc. It is known that the performance of the nonlinear nanophotonic devices strongly relies on the optical resonances and the selection of appropriate nonlinear materials. Here, we demonstrate that the third harmonic generations (THG) can be greatly enhanced at subwavelength scale by incorporating α-Ge2Sb2Te5 (α-GST) into the nanocavity metasurface. Under pumping of a near-infrared femtosecond laser, the THG from the nanocavity metasurface is ∼50 times stronger than that from the bare GST planar film. In addition, the nanocavity metasurface also provides a powerful platform for characterizing the third-order nonlinear susceptibility of the active medium in the cavity. We expect that the GST-based nanocavity metasurface could open new routes for achieving high efficiency nonlinear nanophotonic devices.

We propose and numerically demonstrate a microfluid-enabled spin-selective chiral metasurface with tunable circular dichroism. The chiral metasurface consists of periodic array of gammadion-like multilayer nanostructures. With the help of microfluidic technology, fine tuning of circular dichroism from the chiral metasurface can be achieved. Numerical results show that a broad tuning range of 40 nm can be achieved, while the circular dichroism only shows a slight decrease. Such a proposed device could be potentially useful for chirality detection, polarimetric imaging, and spin-communications.

We propose a liquid-crystal-based tunable plasmonic waveguide filter and numerically investigate its filtering properties. The filter consists of a metal-insulator-metal waveguide with a nanocavity resonator. By filling the nanocavity with birefringent liquid crystals (LCs), we could then vary the effective refractive index of the nanocavity by controlling the alignment of the LC molecules, hence making the filter tunable. The tunable filtering properties are further analyzed in details via the temporal coupled mode theory (CMT) and the finite-difference time-domain (FDTD) method. The simulation results show that the resonant wavelengths have linear redshift as the refractive index of the nanocavity increases and the coupling efficiency is more than 65% without considering the internal loss in the nanocavity and waveguides. These achieved results by the FDTD simulations can be also accurately analyzed by CMT. The compact design of our proposed plasmonic filters is especially favorable for integration, and such filters could find many important potential applications in high-density plasmonic integration circuits.

An electrically tunable three-dimensional holographic photonic crystal made of polymer-dispersed liquid crystals was fabricated using a specially designed prism. This prism split a collimated laser beam into four beams which interfered with each other at the base of the prism to form a three-dimensional spatial light intensity pattern. The spatial light intensity pattern was then recorded inside a cell filled with polymer-dispersed liquid crystals to create photonic crystal structures, which were examined by atomic force microscopy and scanning electron microscopy. The diffraction and electrically tunable properties were also presented. The electro-optical response time was also measured.

We report maskless fabrication of high-aspect-ratio slanted annular aperture arrays (SAAAs) in gold films using focused ion beam lithography. By tilting the substrate, SAAAs with the desired tilting angle can be fabricated. Our experimental results demonstrate accurate control over aperture size, obliqueness, and reproducibility. We also show that the resulted plasmonic resonances of SAAAs can be effectively tuned via obliqueness control. This versatile approach may enable fabrication of more complicated plasmonic nanostructures. The demonstrated gold SAAAs could also find many potential applications in plasmon-assisted sensing and surface enhanced spectroscopy.

In this work, we have presented a novel local surface plasmon resonance (LSPR) sensor based on the U-bent plastic optical fibre (U-POF). Firstly, a layer of discontinuous silver (Ag) thin film was deposited on the U-POF and then the Ag film was covered by a layer of cladding synthesized by polyvinyl alcohol (PVA), graphene and silver nanoparticles forming the PVA/G/AgNPs@Ag film. The normalized transmittance spectrum of the LSPR sensor have been collected in a range of the refractive index (RI) from 1.330 to 1.3657 in ethanol solution, and 700.3 nm/RIU sensitivity of the developed LSPR sensor has been demonstrated. By experiments, we demonstrated that the graphene could improve the sensitivity of the LSPR sensor and delay the oxidation process of the AgNPs effectively to keep the stability of the LSPR sensor. The LSPR sensor also exhibited good sensitivity and linearity in the detection of glucose solutions. This work shows that the developed LSPR sensor may have promising applications in biosensing.

Lasing action was observed in a one-dimensional photonic crystal made of rhodamine B dye-doped holographic polymer-dispersed liquid crystal gratings. The results showed that the lasing peak centered at about 604 nm, with a full width at half maximum of about 6.0 nm. The threshold pumping energy was about 80 µJ at the pumping wavelength of 532 nm. Theoretical simulation showed that the lasing from this structure happened at the photonic bandedge of the one-dimensional photonic crystal. The lasing modes were also investigated.

Cupric oxide (CuO) nanoparticles were grown on zinc oxide (ZnO) nanorod (NR) arrays to form ZnO−CuO corn-like composites via a simple two step solution-based method. First, ZnO nanorods were grown on a glass substrate by the hydrothermal method. Afterwards, CuO crystals were photochemically deposited on ZnO NRs using ultraviolet (UV) light irradiation at room temperature. The density and size of CuO nanoparticles (NPs) on ZnO NRs can be controlled by the irradiation time of UV light. The structural and optical properties of ZnO−CuO nanocomposites were characterized by using various techniques such as UV-vis absorption spectroscopy, photoluminescence, scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. ZnO−CuO nanocomposites show an excellent improvement in photocatalytic characteristics compared to bare ZnO NRs.

Ultrafine 50 nm line and space nanogratings were fabricated using nanoimprint lithography, and were further used as an alignment layer for liquid crystals. The surface morphologies of the nanogratings were characterized and their surface energies were estimated through the measurement of the contact angles for two different liquids. Experimental results show that the surface energies of the nanogratings are anisotropic: the surface free energy towards the direction parallel to the grating lines is higher than that in the direction perpendicular to the grating lines. Electro-optical characteristics were tested from a twisted nematic liquid crystal cell, which was assembled using two identical nanogratings. Experimental results show that such a kind of nanograting is promising as an alternative to the conventional rubbing process for liquid crystal alignment.

A novel bionic network nanostructure of zinc oxide (ZnO), which is similar to the microstructure of a butterfly wing, was first fabricated by a vapor-phase transport method using zinc powder as a source. These bionic nanostructures are composed of three ordered multi-aperture gratings. Similar to the optical effect of butterfly wings, the diffraction patterns of the bionic network of ZnO were observed. The mechanism of the optical function was discussed based on the physical model of multi-aperture diffraction.