基于SLM的计算全息三维显示视角扩展编码

提出一种利用高分辨液晶空间光调制器的高衍射级来增大再现视角的计算全息编码方法.该方法首先对被记录物波的视角超出所用高分辨液晶空间光调制器允许范围的物波信息进行预处理,使预处理后的物波视角满足抽样定理;然后再进行计算全息编码.这种计算全息图可利用高分辨液晶空间光调制器的特定高衍射级恢复再现被记录物波.文中给出了该方法的编码原理及物波函数的预处理公式,并通过设计实例和实验结果证明了该方法的可行性.     

Electrically controllable unidirectional transmission in a heterostructure composed of a photonic crystal and a deformable liquid droplet

We propose a new method to realize the tunable unidirectional behavior using a heterostructure composed of a one-dimensional photonic crystal and a deformable liquid droplet. We can control the occurrence of the unidirectional behavior in the heterostructure by adjusting the voltage applied on the liquid system. It is demonstrated that when the voltage is not applied most of incident-wave energy can be transmitted through the heterostructure for backward lights. While the forward lights can’t be transmitted, if the voltage is high enough, the one-way behavior disappears. The applied voltage to control the one-way behavior may be relatively low. Thereby, we can expect that the heterostructure may have potential applications in optical devices.     

Implementation of an analogue model of a memristor based on a light-dependent resistor

In this paper,an analogue model of a memristor using a light-dependent resistor(LDR) is presented.This model can be simplified into two parts:a control circuit and a variable resistor.It can be used to easily verify theoretical presumptions about the switching properties of memristors.This LDR-based memristor model can also be used in both simulations and experiments for future research into memristor applications.The paper includes mathematical models,simulations,and experimental results.     

Propagation of a focused light beam in a circuital system of tunnel-coupled waveguides

The propagation of a pencil beam in a circuital system of tunnel-coupled waveguides is considered. It is shown that the beam periodically focuses into a point when moving along the trajectory. A maximal number of waveguides supporting the propagation of the beam can be estimated in simple terms. The cross-sectional area of the waveguides can be subdivided into three zone with the beam pulsing only in the central one.     

混响场中用相关传声器识别声源直达声的近似工程法

本文研究了在混响场中用相关传声器识别主声源直达声的近似工程法，包括理论及实验技术。采用该方法对一个置于混响声污染下的恒定声源进行了直达声测量，并将测量结果与该恒定声源的消声室测量结果进行了比较，结果表明：相关传声器近似工程法在很大程度上能减少混响声对主要源声压测量的干扰，从而能在混响声场中获取一定精度的主声源声压级。     

Influence of a magnetically permeable surface layer on transient electromagnetic field of a vertical magnetic dipole on a two-layer conducting earth

The transient electromagnetic field, in the frequency domain, on a two-layered conducting earth is reexamined when the usually neglected magnetic permeability contrast is considered. It is shown that for two-layered earth model, where the upper is permeable, the electromagnetic induction response is modified over the nonpermeable case. It is obtained as a summation of waveguide modes plus contributions from branch-cuts in the complex plane of the longitudinal wave number. The results from this paper can be used to evaluate numerical solution of other more complicated forward modeling algorithms. It can also be used in developing fast and simple interpretation tools, which can deliver quick estimation of the earth structure at the field.     

Reconstructing a complex field from a series of its near-field diffraction patterns

We propose a method for reconstructing a complex field from a series of its near-field diffraction patterns.This method is based on the paraxial Fresnel diffraction equation without making further approximations.Numerical simulations are presented showing that a complex field can even be reconstructed with moderate qualities from its two near-field diffraction patterns and almost exact reconstructions can be obtained when three or more diffraction patterns are used.We also show by numerical simulation that the correct diffraction distances can be recovered in case only coarsely measured values are available.This method may be applied to phase imaging of weak-absorption objects.     

Interaction of a bubble and a bubble cluster in an ultrasonic field

Using an appropriate approximation, we have formulated the interacting equation of multi-bubble motion for a system of a single bubble and a spherical bubble cluster. The behavior of the bubbles is observed in coupled and uncoupled states. The oscillation of bubbles inside the cluster is in a coupled state. The numerical simulation demonstrates that the secondary Bjerknes force can be influenced by the number density, initial radius, distance, driving frequency, and amplitude of ultrasound. However, if a bubble approaches a bubble cluster of the same initial radii, coupled oscillation would be induced and a repulsive force is evoked, which may be the reason why the bubble cluster can exist steadily. With the increment of the number density of the bubble cluster, a secondary Bjerknes force acting on the bubbles inside the cluster decreases due to the strong suppression of the coupled bubbles. It is shown that there may be an optimal number density for a bubble cluster which can generate an optimal cavitation effect in liquid for a stable driving ultrasound.     

Experimental Study of a High Power Coupler for a Tunable Cavity Formed by a Vane-Type Structure

In this study, a high power coupler designed for a tunable planar cavity is experimentally tested. The cavity consists of a periodical vane-type structure, of which the height of the vane can be mechanically adjusted so that the resonance frequency can be fine tuned. The cavity is designed to be operated at mode and resonant at 2.45 GHz. The high power coupler is composed of a rectangular waveguide and a cylindrical ceramic rod with tapered ends. One end of the ceramic rod is intruded into the gap between two vanes of the cavity. Through this coupler, the TE₁₀ mode of the rectangular waveguide is converted into the TE₁₁ mode of the ceramic rod and then couples to the TEM mode in the gap between vanes of the cavity. Experimental results show that a microwave power up to 5 kW can be effectively transmitted to excite the mode of the cavity . This cavity can be used to excite large area plasmas     

Development of a self-oscillating ultrasonic micro-motor and its application to a watch

We have developed an ultrasonic micro-motor for use as a micro-actuator in place of an electromagnetic motor. This ultrasonic micro-motor, which can be driven by a single signal and in which the change of the direction of the rotor movement can be made easily by selecting the electrode to apply the driving signal, can easily construct a self-oscillating circuit and simplify the driving circuit. We have also simplified the motor structure, which is easy to miniaturize and mass-produce. We applied a version of this motor with a diameter of 8 mm to a vibration alarm, and one with a diameter of 4.5 mm to a driving source of a calendar mechanism in a watch. This ultrasonic micro-motor is expected to be of use as a new driving source in a broad range of fields.     

Interaction of a bounded ultrasonic beam with a thin inclusion inside a plate

A theoretical study of the reflection of a two-dimensional Gaussian ultrasonic beam, incident at a Lamb angle of a plate containing a thin rectangular inclusion at an arbitrary position, is presented on the basis radiation mode theory. The inclusion is parallel to the plate surface and its thickness is assumed to be much smaller than the ultrasonic wavelength. It is shown that the amplitude and phase of the reflected beam profile can be used for accurate inclusion characterization. However, this only holds for certain internal positions of the inclusion and for material combinations that do not strongly perturb the excitation of Lamb waves in the plate. When these conditions are satisfied, it is possible to define the Lamb waves and the associated experimental conditions for which good estimates can be obtained of the position of the beginning point of the inclusion as well as of the length and the thickness of the inclusion.     

UV-laser-based fabrication of a planar,polymeric Bragg-structure

The fabrication of a planar polymeric Bragg-structure by a UV-laser-lithographic method is described in this paper: A polymeric substrate is irradiated by a UV-excimer laser inducing photo-reactions at the substrate surface. In this way the polymeric material can be locally removed from the substrate surface or the surface refractive index can be locally changed in a reproducible way. Several integrated optical microstructures can be generated by UV-laser-lithographic methods (amplitude and phase mask methods in contact modus), e.g. waveguides or surface relief gratings. A polymeric planar Bragg-structure is realized which can be used as a (de-) multiplexer in optical telecommunications technology or as a temperature or strain sensor in optical sensor technology.     

An application of a combined gradient system to stabilize a mechanical system

A gradient system and a skew-gradient system can be merged into a combined gradient system. The differential equations of the combined gradient system are established and its property is studied. If a mechanical system can be represented as a combined gradient system, the stability of the mechanical system can be studied by using the property of the combined gradient system. Some examples are given to illustrate the applications of the results.     

The design of a polarizing beam splitter made from a dielectric rectangular-groove grating

It has been reported that a polarizing beam splitter based on a rectangular-groove grating (a grating polarizing beam splitter) can be easily designed for specific applications using the modal method. In this paper, the eigenvalue equation of the modal method is transformed to a new form. Using this new form of the eigenvalue equation, it is shown that the design of a grating polarizing beam splitter can be independent of the incident wavelength. The period and the groove depth can be designed using values normalized to the incident wavelength, which apply to a range of wavelengths as long as the effects of dispersion can be neglected. Numerical simulations of fused silica gratings are presented and analyzed. It is concluded that the preferable choice for the grating period is 0.8–0.9 times the incident wavelength.     

一类动力学方程的Mei对称性

研究一类动力学方程的Mei对称性的定义和判据，由Mei对称性通过Noether对称性可找到Noether守恒量.由Mei对称性通过Lie对称性可找到Hojman守恒量.同时，也可找到一类新型守恒量.     

Local interactions and the global organization of a two-phase flow in a branching tree

The transport of liquid plugs in a microfluidic branching tree is studied experimentally. The global flow pattern can be either symmetric or asymmetric, with daughter plugs dividing in synchrony or asynchrony as a function of the driving flow rate and the network geometry. For trees with narrowing channels, the plugs always reach the exits even at low flow rates. In contrast, only one path is opened in networks with widening channels when the flow rate is low. This behavior is explained by a comparison of the pressure drop necessary to drive viscocapillary motion of plugs in straight channels with the nonlinear pressure variations as a plug passes a bifurcation. A model is built, which predicts that only narrowing networks can be fully filled, while widening networks can never be fully invaded by a two-phase flow.     

Remote preparation of a two-particle state using a four-qubit cluster state

We present a scheme of remote preparation of two-particle states using a particular four-qubit cluster state as the quantum channel. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. Our results show that in general such remote state preparation can be realized with a probability of 1/4. But in several special cases, the probability of success can be improved to 1/2 or even 1.     

Demonstration of sharp switching from a power-symmetric NOLM and a polarizer

We demonstrate theoretically, experimentally and numerically that a steep all-optical transfer characteristic can be obtained from a power-symmetric NOLM, including a quarter wave retarder and highly twisted fibre, followed by a polarizer. We first develop a theoretical analysis to show that, if the input polarisation is chosen linear, then for a correct choice of the wave plate and input polarisation angles the transmission grows from zero with a 4 dB/dB slope as power is increased, two times faster than can be obtained with a NOLM alone. An experimental study is then realised, which supports the theoretical results. Steep switching is demonstrated for reasonably low peak power levels that do not exceed 8 W, less than one third of the NOLM critical power. In addition, using the same setup we demonstrate the possibility to obtain a sinusoidal transmission characteristic that cancels out for a particular nonzero value of input power, which can be easily adjusted simply through rotation of the wave plate and output polarizer. This setup would be very useful in the frame of optical pulse shaping and signal processing applications, among others.     

Relative Energy Shift of a Two-Level Atom in a Cylindrical Spacetime

We investigate the evolution dynamics of a two-level atom system interacting with the massless scalar field in a Cylindrical spacetime. We find that both the energy shifts of ground state and excited state can be separated into two parts due to the vacuum fluctuations. One is the corresponding energy shift for a rest atom in four-dimensional Minkowski space without spatial compactification, the other is just the modification of the spatial compactified periodic length. It will reveal that the influence of the presence of one spatial compactified dimension can not be neglected in Lamb shift as the relative energy level shift of an atom.     

Trapping a dark soliton pulse within a nano ring resonator

We propose the interesting results that a dark soliton pulse can be localized within a nonlinear nano-waveguide. The system consists of nonlinear micro and nano ring resonators, whereas the dark soliton can be input into the system and trapped within the nano-waveguide. A dark soliton pulse is input into a ring resonator and chopped to be the smaller pulses. The required pulse is filtered and amplified, which can be controlled and localized within the nano-waveguide. The localized bright soliton is also reviewed and discussed.