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The Z-scan technique is used to investigate the effects of refractive index change (RIC) associated with photoisomerization for two cases: in which the sample is pumped and probed by the same elliptically polarized light, and in which the sample is pumped by a linearly polarized light and probed by another linearly polarized light. Both experimental and theoretical results show that for the first case, this effect depends upon the polarization of the light; that is, when the polarization changes continuously from circularly polarization to linearly polarization, the effects of RIC becomes stronger. For the second case, the effect is similar to the effects of saturable Kerr effect, whose nonlinear coefficient n2 is measured. [ABSTRACT FROM AUTHOR]

From the perspective of bond relaxation under multifield perturbation, we examined the dielectric response to perturbation for GaN, InN, and ZnO. It is found that the surface local bond contraction and quantum entrapment dictate the size dependency of the dielectric constant at the nanometer scale. Reproduction of experimental observations under temperature, pressure, and tensile strain derived respective information of the Debye temperature and atomic cohesive energy, the bulk modulus and energy density, the bond length, bond energy, and force constant. The formulation of the multifield effects on the dielectric constant of semiconductors is beyond the scope of the available approaches, which not only revealed quantitative information but also provides deeper insight into the physical origin of the dielectric response to perturbations. [ABSTRACT FROM AUTHOR]

We study the one-way transmission and mode conversion of elastic waves by a hybrid phononic-crystal structure that consists of two mutually perpendicular phononic-crystal waveguides connected by a resonant cavity. Based on the mode matching mechanism between the cavity and waveguides, the symmetrical waves incident on the waveguide entrance are converted into antisymmetric modes and exit the waveguide. However, for the same waves incident on the structure from the waveguide exit, no output waves are transmitted toward the waveguide entrance because the modes in the waveguides and the cavity are mismatched. On the basis of this unique property, we designed a polarization-sensitive composite structure to measure the angle between two components of incident mixed elastic waves. [ABSTRACT FROM AUTHOR]

An easy-to-implement scheme to split self-collimated acoustic beams in sonic crystals (SCs) is proposed by introducing line-defects into SCs, by which an incoming self-collimated beam can be split into a 90°-bended one and a transmitted one with an arbitrary power ratio by adjusting the value of defect size. An all-angle and wide-band splitting instrument is demonstrated with nearly perfect efficiency (more than 90%) for Gaussian beams at a wide range of incident angles. Splitting effect for a point source as input is also realized, in which two subwavelength images of the source, i.e., a bended one and a transmitted one, are formed by our designed splitting structure. Finally, the proposed one-to-two splitting scheme is generalized to one-to-N (N > 2) cases by inserting more rows of line defects into the SC. [ABSTRACT FROM AUTHOR]

We investigate theoretically subwavelength imaging by acoustic metamaterial slabs immersed in the liquid matrix. A near-field subwavelength image formed by evanescent waves is achieved by a designed metamaterial slab with negative mass density and positive modulus. A subwavelength real image is achieved by a designed metamaterial slab with simultaneously negative mass density and modulus. These results are expected to shed some light on designing novel devices of acoustic metamaterials. [ABSTRACT FROM AUTHOR]