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Two electro-optical phenomena of liquid-crystal blue phase with cubic lattice structure-(1) a fast and reversible shift in reflection band and (2) a phase transition from blue phase to chiral nematic phase-are observed in this study. By increasing the magnitude of a vertical electric field, the reflected wavelength of the blue phase can be shifted to a longer wavelength in a range of 80 nm within a few ms. This reflection band shift is induced by the reorientation of liquid-crystal molecules constructing double twist cylinders, which induces lattice distortion of the blue phase. [ABSTRACT FROM AUTHOR]

Correlations between the stability of blue phases and the physical parameters of liquid-crystal hosts are reported in this study. Experimental results show that liquid-crystal blue phases are more thermostabilized when the dielectric anisotropy is reduced or the elastic constants increased. These correlations can be explained by Defect theory and Landau theory for blue phases. Moreover, the results give us the clues to develop more suitable blue-phase materials for fundamental researches or fast photonic devices. [ABSTRACT FROM AUTHOR]

We describe a device geometry using interdigital electrodes that enables the electrically driven reorientation of smectic A layers from a homeotropic state (dark between crossed polarizers) to a planar state (bright between crossed polarizers) and back again. The resulting electro-optic effect is strongly bistable and gives high contrast ratio and fast response, rendering it a potential candidate for flexible-display applications. [ABSTRACT FROM AUTHOR]

The response times of rotational molecular orientation of neat and carbon-nanotube-doped nematic liquid crystals were acquired through the measurement of transient current induced by a direct-current step voltage and from optical transmission data. A model based on the dielectric displacement current was developed to describe the electric field dependence of the response and to yield a rotational viscosity that would decrease with increasing concentration of carbon nanotubes. Optical dynamic response also showed a reduced rotational viscosity, with the lightly doped cells exhibiting a faster relaxation process than that of the neat cell. [ABSTRACT FROM AUTHOR]

Transient currents induced by the polarity reversal of an applied dc electric field have been measured in planar-aligned nematic liquid-crystal cells. Experimental results indicate that a minute addition of carbon nanotubes as a dopant leads to a reduction of the ion concentration and thus suppresses the undesired field-screening effect. Observed simultaneously is a higher charge mobility in the doped cells in the presence of a strong field. Such increase of mobility, in comparison with that of undoped counterparts, is attributed to the parallel alignment of both the long axis of carbon nanotubes and the nematic director along the electric field. [ABSTRACT FROM AUTHOR]

A photonic switch of 2×3 structure was designed and fabricated using the thermo-optical effect of polymer materials. By setting sectional electrode and exerting voltage to proper section, we can control the reflection region length and ray propagation trace. Input light can be switched freely among three output ports. The experiment results show that, for the “half-reflection” state, the extinction ratio is 16.6 dB for the half-reflection port; and for the “bar” state, the extinction ratio for the reflection port is 26.8 dB. The power consumption is on the scale of 100 mW and varies with different function mode. [ABSTRACT FROM AUTHOR]

This letter introduces a three-dimensional manufacturing approach to the rapid processing of microfluidic structures using a scanning laser system. This technique takes advantage of the nonuniform distribution of laser power along its incident axis. The laser processing perpendicular to the specimen surface is realized by fine-tuning focus levels and laser intensity. A large number of microfluidic components such as cantilevered valves, embedded channels, and other shapes requiring gaps between layers are demonstrated in a single layer. With this process, a class of microstructures with designed-in functionalities can be developed. [ABSTRACT FROM AUTHOR]

This letter presents a miniaturized, fast, and high resolution thermal detector, in which a heat absorbing element and a temperature sensitive microelectromechanical system (MEMS) resonator are perfectly overlapped but separated by a microscale air gap. This unique design guarantees efficient and fast (∼10s μs) heat transfer from the absorbing element to the temperature sensitive device and enables high resolution thermal power detection (∼nW), thanks to the low noise performance of the high quality factor (Q = 2305) MEMS resonant thermal detector. A device prototype was fabricated, and its detection capabilities were experimentally characterized. A thermal power as low as 150 nW was experimentally measured, and a noise equivalent power of 6.5 nW/Hz1/2 was extracted. A device thermal time constant of only 350 μs was measured (smallest ever reported for MEMS resonant thermal detectors), indicating the great potential of the proposed technology for the implementation of ultra-fast and high resolution un-cooled resonant thermal detectors. [ABSTRACT FROM AUTHOR]

Zero-energy states in tunnel spectra, an important manifestation of topological superconductivity, have been the focus of the field of topological phases of matter. However, experimentally creating and controlling the zero-energy states is difficult, e.g., it requires a large magnetic field in the case of topological superconductivity. Here, we report on an effective approach to generate controllable zero-energy states in the superconducting Rashba oxide heterostructure by in-plane magnetic field cooling. A pronounced zero-bias conductance peak emerging below a threshold magnetic field down to zero after in-plane magnetic field cooling of a Rashba perovskite oxide heterostructure connecting to an s-wave superconductor. We further demonstrate the high tunability of the zero-energy states between a zero-bias conductance peak and a zero-bias conductance valley by electrical gating at a zero magnetic field. Our theoretical analysis indicates that the in-plane magnetic field or magnetization could lead to finite center-of-mass momentum pairing that supports topological zero-energy states in the Rashba system and provides an opportunity to manipulate topological zero-energy states through gating. [ABSTRACT FROM AUTHOR]

The thermal expansion of as-prepared and annealed silver nanowires embedded in anodic alumina membranes with different diameters was studied by in situ x-ray diffraction in the temperature range from 25 to 800 °C. For both the as-prepared and annealed samples, the coefficients of thermal expansion have “V” shape change as the diameters increase; and the minimum values of the coefficients of thermal expansion do not correspond to the same diameters of nanowires. The collective effects of the surface tension, the limit effects of anodic alumina membrane, and the vacancies incorporated into the silver lattice were responsible for the thermal expansion. [ABSTRACT FROM AUTHOR]

Thermal expansion of as-prepared and annealed ordered arrays of silver nanowires embedded in anodic alumina membranes (AAMs) was studied by in situ x-ray diffraction measurement in the temperature range from 25 to 800 °C. The axial thermal expansion coefficient (TEC) for the as-prepared nanowires is 6.35×10-9/°C and 6.02×10-6/°C below and above 650 °C, respectively. However, the TEC of the annealed sample turns from 2.32×10-6/°C to 12.06×10-6/°C when the temperature is above 350 °C. The collective effects of the intrinsic expansion, surface pressure, the limit effect of AAM, and the vacancies incorporated into the silver lattice were responsible for the thermal expansion. [ABSTRACT FROM AUTHOR]

The effect of source-gate spacing on graphene filed effect transistors has been investigated. Reducing the source gate spacing allows for a significant improvement on both the direct current and radio frequency (RF) performances. Instead of the generally considered output conductance, our results suggest that the access resistances at the un-gated region contribute more to the maximum oscillation frequency (fmax). Further analysis reveals that the ratio of cut off frequency (fT) to fmax is also sensitive to the resistances at source-gate spacing. This work can be used to guide the further optimization of graphene-based RF devices. [ABSTRACT FROM AUTHOR]

Controlling the light transmission in the epsilon-near-zero channel, which is covered by the perfectelectric- conductor (PEC) walls, has been demonstrated in [L. Yang, T. Hu, A. Shen, C. Pei, B. Yang, T. Dai, H. Yu, Y. Li, X. Jiang, and J. Yang, Opt. Lett. 39, 1909 (2014)]. In this work, we investigate the possibility of replacing the PEC by some practical metal materials. Based on it, an ultracompact plasmonic switch with the length of 15 nm is presented. Its highest extinction ratio is more than 13 dB, while the 3-dB extinction ratio is obtained with a 0.41V gate voltage. [ABSTRACT FROM AUTHOR]