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Implementation of multifunctional optical elements by controlling spectrum and wavefront simultaneously with conventional approaches is a difficult task due to their complicated structures and fabrication processes. We present a method to construct multifunctional optical components to achieve independent function at every operating wavelength in a shared-aperture configuration. The component contains amounts of periodical interleaved sectors composed of a metasurface layer sandwiched by two distributed Bragg reflectors (DBRs) and another metasurface layer upon the former. To demonstrate this method, we design and simulate a component which can focus the light wave at 0.521 μ m on a spot and deflect the wave at 0.585 μ m to a desired angle. The realized functions for different wavelengths will not interfere with each other, showing a low-crosstalk characteristic. Further improvement is applied to reduce the diffraction effect for light focusing and deflecting with smaller sidelobes by replacing the fixed period of the interleaved sectors with random periods. This work may provide an effective way of controlling the multiwavelength electromagnetic waves in extensive integrated optical systems.

Using a double-plate wave maker, a series of laboratory experiments of internal solitary wave (ISW) loads on semi-submersible platforms were conducted in a density stratified fluid tank. Combined with experimental results, a numerical flume based on the Navier-Stokes equations in a two-layer fluid is developed to simulate nonlinear interactions between ISWs and a semi-submersible platform. The numerical results of horizontal and vertical forces, as well as torques on the semi-submersible platform also agree well with the experimental measurements. Besides, the numerical results indicate that the horizontal and vertical forces on the semi-submersible platform due to ISWs can be divided into three components, namely the wave pressure-difference forces, viscous pressure-difference forces, and the frictional force which is negligible. For the horizontal force, the wave and viscous pressure-difference components are of the same order, implying that the viscous effect is significant. For the vertical force, the contribution of the viscous pressure-difference is not important. Moreover, the diffraction effect is significant for horizontal force and insignificant for vertical force. Hence, it is feasible to estimate the vertical load using the Froude-Krylov approach.

A digital laser dynamic caustics experimental system is utilized to study the dynamic characteristics of propagation of main cracks and secondary cracks in PMMA medium with flaws under explosion loads. Prefabricated through-cracks are found to open or close as a result of the explosion stress wave reflection from these flaws, which weakens the dynamic behaviors of the main cracks. These main cracks generally do not pass through prefabricated cracks and continue to propagate. Secondary cracks are generated from the ends of the prefabricated through cracks. The initiation and propagation of secondary cracks are caused by the diffraction effect of the tensile stress concentration at both tips of the flaws. The cracking angles of the secondary cracks are closely related to the prefabricated cracks and the incident angle of the explosion stress wave. The secondary cracks initiate from the direction of the maximum energy release rate, and exhibit the mixed fracture mode. The mechanical characteristic values such as the crack length, propagation velocity, and DSIF of main crack that are not directly affected by prefabricated through-cracks are much greater than the values for secondary cracks. Under explosion load, the initiation toughness is from 0.5 to 0.65 MN/m3/2, and the arrest toughness is from 0.25 to 0.35 MN/m3/2.

Off-axis electron holography has been used to quantitatively determine the mean inner potential of ZnO. [0001] grown ZnO nanowires with hexagonal cross-sections were chosen as our samples because the angle between the adjacent surfaces is 120°, as confirmed by electron tomography, so the entire geometry of the nanowire could be precisely determined. The acceleration voltage of the transmission electron microscope was accurately calibrated by convergent beam electron diffraction (CBED)-higher-order Laue-zone (HOLZ) analyses. ZnO nanowires were tilted away from zone-axis to avoid strong dynamical diffraction effect, and the tilting angles were determined by CBED patterns. Our experimental data found a mean inner potential of ZnO as 14.30±0.28 V.

s Existing acoustic diodes are solid–liquid systems and do not involve the inherent anisotropy of solid media. They are based on either the nonlinear effect or the diffraction effect. A kind of new acoustic diodes is proposed in this paper. These new acoustic diodes are all solid medium systems. They are based on the anisotropy of solid media and complete linear acoustics. Compared with the acoustic diodes based on the nonlinear effect, these acoustic diodes proposed here own higher transmission in their forward direction.

Diffraction effect of the injected beam in axisymmetrical structural CO2 laser is studied based on the injection-locking principle. The light intensity of the injected beam at the plane where the holophotes lie is derived according to the Huygens–Fresnel diffraction integral equation. And then the main parameters which influence the diffraction light intensity are given. The calculated results indicate that the first-order diffraction signal will play an important role in the phase-locking when the zero-order diffraction cannot reach the folded cavities. The numerical examples are given to confirm the correctness of the results, and the comparisons between the theoretical and the experimental results are illustrated.

A method for uniformizing a Fourier spectrum is presented for optical holographic storage. The input pattern is modulated by an optimized phase mask, which can be designed by using amplitude-phase retrieval algorithms. The spectral amplitude distribution in the aperture of the recording medium is uniformized by the diffraction effect of the phase mask. Simulation results show that the uniformity is greatly improved.

Circular dichroism in angular distribution was observed for the valence band photoelectron from nonmagnetic and nonchiral material Si(001) with the incident photon energy in UPS region. The obtained two-dimensional angular distributions are to a certain extent consistent with an analysis of simple electronic dipole transition. Calculated angular distributions based on highly accurate one-step model showed better agreement considering photoelectron diffraction effect.

The study shows that the rise and decay of train noise is best modelled by assuming the train noise to be a line source with dipole directivity. It is consistent with previous studies on train noise propagation. In planning new highrise buildings, the blocks are usually built parallel to the elevated viaduct of the rapid transit system. It is the normally held view that parallel blocks built perpendicular to the viaduct will have adverse train noise effect. Parallel blocks inclined to the elevated viaduct of the transit system do have the adverse effect of multiple reflections. However, the increase due to multiple reflections is more than offset by the shielding and diffraction effect from the blocks on the train noise. Inclining the parallel blocks could result in a reduction of 5 dB (A) of the peak train noise. The study shows that inclining the blocks will have a beneficial effect on the train noise profile.

Higher-order Laue zone (HOLZ) patterns are observed in convergent-beam electron diffraction (CBED) patterns of Si-Ge alloys and the dynamical effect on HOLZ lines is discussed in relation to the kinematical approximation to simulate the HOLZ lines. Double lines often appear from one HOLZ reflection due to the excitation of the first and second branches of the zeroth-layer dispersion surface. The magnitude of the systematic line shift from the line positions predicted by the kinematical simulation changes sensitively with specimen thickness and alloy composition depending on which branch is dominantly excited. The kinematical simulation is applicable to accurate determination of lattice parameters with a proper correction δ E : a difference between the effective electron energy and the actual microscope operating voltage. Usefulness of the kinematical simulation is demonstrated in the investigation of the segregation in a Si-Ge alloy.

A theoretical investigation of the linear regime of the FEL amplifier operation with regard to the influence of the diffraction effect, the space charg With the help of the Laplace transformation method an analytic solution of the self-consistent field equations at the given conditions at the input of

In studying the dynamical diffraction effect of neutrons it has been clarified that eigenstates of a quantum system composed of periodic potentials with free spaces on both ends play a crucial role in determining the Bragg reflection, rocking curves, Pendellosung effect, and so on. These eigenstates can be called virtual states, since the occupancy probability within the potential region is significantly modified by the existing potential, even though the energies of concern are much larger than the potential barrier heights.

Diffraction rings of 3.7 MeV α-particles passing through thin silicon crystals of thickness 3000 A were observed around the 〈110〉 axis direction. The angular radii of the rings agree well with those calculated assuming the incident particle being scattered by a lattice atom in the direction of the 〈110〉 axis and subsequently being again scattered by a neighboring lattice atom in the same direction. It indicates that the relative normal displacement of two neighboring atoms along 〈110〉 is less than 0.007 A.

The experimental results obtained with a propane bubble chamber concerning the coplanar and non-coplanar (p, 2p) reaction in 12 C are summarized. The nuclear diffraction effect has been observed. The theoretical interpretation of the recoil momentum distribution is discussed.

The question of whether the pulses attributed to second sound can also be attributed to a diffraction effect is analyzed. The diffraction-wave hypothesis is shown to have fundamental as well as practical shortcomings, making it an unsuitable alternative explanation.