Propagation of Airy beams from right-handed material to left-handed material

Based on the ABCD matrix formalism,the propagation property of an Airy beam from right-handed material（RHM） to left-handed material（LHM） is investigated.The result shows that when the Airy beam propagates in the LHM,the intensity self-bending due to its propagation in the RHM can be compensated.In particular,if the propagation distance in the RHM is equal to that in the LHM and the refractive index of the LHM is n L =-1,the transverse intensity distribution of the Airy beam can return to its original state.

A Note on Self-Accelerating Olver and Olver-Gauss Beams

The recent introduction by Belafhal et al. [Opt. and Photon. J. 5, 234-246 (2015)] of mth-order Olver beams as a novel class of self-accelerating nondiffracting solutions to the paraxial equation is a direct contradiction to the seminal work of Berry and Balazs who determined that the infinite-energy Airy wave packet is the only accelerating nondiffracting solution to the (1 + 1)D Schrödinger equation. It is shown in this note that the work of Belafhal et al. is valid only for m=0, which coincides with the Airy solution.

Generation and regulation of two-dimensional autofocusing Airy beams based on holographic metasurfaces

This paper proposes a new method to generate a two-dimensional(2D)Airy beam and Airy autofocusing beam by using the scalar holographic metasurface with amplitude-phase modulation in the microwave band.The proposed holographic metasurface comprises subwavelength patch unit cells with a period of fewer than 1/8 wavelengths,which means that it has the finer sampling for electromagnetic waves and can simultaneously achieve precise modulations for the amplitude and phase of electromagnetic waves.Firstly,the 2D-Airy beam with quasi-non-diffraction and selfbending characteristics is generated,from which the holographic metasurface is designed to realize four different 2D-Airy beams with the same focus,achieving the 2D-Airy autofocusing beam in the microwave frequency.The holographic metasurface for Airy beam generation has high efficiency and an ultra-lower profile.Meanwhile,for applying the Airy beam in wireless power transfer(WPT),the efficiency of the generated Airy beam and Airy autofocusing beam is calculated for the first time in the microwave field.The simulation results show that the efficiency of the 2D-Airy beam can reach 66%at 150 mm away from the metasurface,while the efficiency of the 2D-Airy autofocusing beam at the focus,which is 280 mm from the metasurface,can reach 35%.The theoretical,simulated,and measured results show that the proposed method and holographic metasurfaces can flexibly achieve the special characteristics of self-autofocusing and self-bending Airy beams in the microwave domain,providing an effective path for wireless power transfer(WPT)scenario with radial obstructions.

海洋顺应式结构的非线性自由振动分析

将海洋平台中顺应式结构简化为底端具有线扭转弹簧支撑,顶端附有集中质量块的水中柔性梁。采用连续介质力学方法,在小变形和大转角的假定下,应用大挠度理论建立了梁的非线性耦合运动控制方程和边界条件。在Morison方程的基础上研究了流体力的作用效应。运用有限差分法和Runge-Kutta法得到了方程数值解,分析了梁在真空中和在水中无阻尼、有阻尼的自由振动,并对大挠度理论下非线性结构与横截面转角近似下非线性结构及线性结构进行了比较。

海洋顺应式结构的非线性动力响应分析

将海洋平台中顺应式结构简化为底端具有线弹性扭转弹簧约束，顶端附有集中质量块的水中柔性梁。采用连续介质力学方法，应用大挠度理论建立了梁的非线性耦合运动控制方程和边界条件。应用Morison方程给出了流体力的表达式。运用有限差分法和Runge—Kutta法得到了方程数值解。分析了梁在各种激励下的非线性振动特性，以及拖拽系数对梁振动的影响，并对大挠度理论下非线性梁与横截面转角近似下非线性梁及线性梁三种梁的振动响应进行了比较。