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A quasi-rectangular waveguide polymer Mach-Zehnder (M-Z) electro-optic (EO) modulator based on an organic/ inorganic hybrid material with thermal bias control is fabricated and demonstrated. Linear bias for the modulator is obtained through thermo-optic effect. The optical output is adjusted by changing phase difference between the two arms of the M-Z interferometer. A power consumption of 16.1mW for ?? phase change is observed owing to the application of silica cladding. This approach is proved to be effective to suppress direct current drift in polymer EO modulators. [ABSTRACT FROM AUTHOR]

Recently, θ-TaN was proposed to be a topological semimetal with a new type of triply degenerate nodal points. Here, we report studies of pressure dependence of transport, Raman spectroscopy and synchrotron x-ray diffraction on θ-TaN up to 61 GPa. We find that θ-TaN becomes superconductive above 24.6 GPa with Tcat 3.1 K. The θ-TaN is of n-type carrier nature with carrier density about 1.1 × 1020/cm3at 1.2 GPa and 20 K, while the carrier density increases with the pressure and saturates at about 40 GPa in the measured range. However, there is no crystal structure transition with pressure up to 39 GPa, suggesting the topological nature of the pressure induced superconductivity. [ABSTRACT FROM AUTHOR]

High-pressure phase transitions of cubic Y2O3 are investigated using in situ synchrotron x-ray diffraction in a diamond anvil cell up to 36.3 GPa. The pressure-induced phase transitions of cubic Y2O3, which display apparent inconsistencies in previous studies, are verified to be from a cubic phase to a monoclinic phase and further to a hexagonal phase at 11.7 and 21.6 GPa, respectively. The hexagonal Y2O3 displays noticeable anisotropic compressibility due to its layered structure and it is stable up to the highest pressure in the present study. A third-order Birch–Murnaghan fit based on the observed pressure-volume data yields zero pressure bulk moduli of 180(3), 196(7) and 177(7) GPa for cubic, monoclinic and hexagonal phases, respectively. [ABSTRACT FROM AUTHOR]

We study the strength and texture of tantalum (Ta) under uniaxial compression up to 80 GPa using an angle-dispersive radial x-ray diffraction technique together with the lattice strain theory in a diamond anvil cell at ambient temperature. The ratio of differential stress to shear modulus (t/G) is found to remain constant above ∼60 GPa, indicating that the Ta starts to experience macro yield with plastic deformation at this pressure. Combined with independent constraints on the high-pressure shear modulus, we find that the Ta sample could support a differential stress of ∼4.67 GPa when it starts to yield with plastic deformation at ∼60 GPa under uniaxial compression. The differential stress in Ta ranges from 0.216 GPa to 4.67 GPa with pressure increasing from 1 GPa to 60 GPa and can be expressed as t = 0.199(33) + 0.075(1)P, where P is the pressure in GPa. A maximum differential stress as high as ∼5.37 GPa can be supported by Ta at the high pressure of ∼80 GPa. In addition, we investigate the texture of Ta under nonhydrostatic compression to 80 GPa using the software package material analysis using diffraction. It is proven that the plastic deformation due to stress under high pressures is responsible for the development of texture. [ABSTRACT FROM AUTHOR]

The work functions of the (110) and (100) surfaces of LaB are determined from ambient pressure to 39.1 GPa. The work function of the (110) surface slowly decreases but that of the (100) surface remains at a relatively constant value. To determine the reason for this difference, the electron density distribution (EDD) is determined from high-pressure single-crystal x-ray diffraction data by the maximum entropy method. The EDD results show that the chemical bond properties in LaB play a key role. The structural stability of LaB under high pressure is also investigated by single-crystal x-ray diffraction. In this study, no structural or electronic phase transition is observed from ambient pressure to 39.1 GPa. [ABSTRACT FROM AUTHOR]

The pressure-induced structural transitions of ZnTe are investigated at pressures up to 59.2 GPa in a diamond anvil cell by using synchrotron powder x-ray diffraction method. A phase transition from the initial zinc blende (ZB, ZnTe-I) structure to a cinnabar phase (ZnTe-II) is observed at 9.6 GPa, followed by a high pressure orthorhombic phase (ZnTe-III) with Cmcm symmetry at 12.1 GPa. The ZB, cinnabar (space group P3121), Cmcm, P31 and rock salt structures of ZnTe are investigated by using density functional theory calculations. Based on the experiments and calculations, the ZnTe-II phase is determined to have a cinnabar structure rather than a P31 symmetry. [ABSTRACT FROM AUTHOR]