线性双折射的波长积累效应对OCS的影响

线性双折射的波长积累效应涉及到用单色光模型替代复色光系统是否合理与可行的问题,因此有必要予以研究.文中先给出了适用于ZF-7玻璃的线性双折射的色散特性公式,再对线性双折射的波长积累效应进行理论分析和计算机仿真.研究结果表明,线性双折射的波长积累效应对OCS系统影响甚微,因此在理论研究中若不考虑其他光学参量的波长积累效应,用单色光模型处理宽带系统的做法有其合理性与可行性.此结果可供从事光学电流传感器研究的同行参考.

The Effect of Hydrostatic Pressure Fields on the Dispersion Characteristics of Fluid-shell Coupled System

The effect of hydrostatic pressure on the vibration dispersion characteristics of fluid-shell coupled structures was studied.Both fluid-loaded cylindrical shells and fluid-filled cylindrical shells were considered.Numerical analysis was applied to solve the dispersion equations for shells filled with or loaded with fluid at various hydrostatic pressures.The results for external pressure showed that non-dimensional axial wave numbers are nearly independent when the pressure is below the critical level.The influence of internal pressure on wave numbers was found significant for the real branch s=1 and the complex branches of dispersion curves.The presence of internal pressure increased the cut on frequencies for the branch s=1 for high order wave modes.

Sub- and Super-Luminal Phenomena in a Doubly Driven Four-Level System

With the occurrence of an adding driving field, the properties of the dispersion and the absorption of a four-level system are changed greatly. The system can produce the normal and anomalous dispersion regions with proper parameters. Here, the driving fields can be seemed as knobs to manipulate the group velocity of a weak probe field between subluminal and superluminal.

Strongly nonlinear long interfacial waves in uniform basic flows and their dispersion relationship

In this paper, long interfacial waves of finite amplitude in uniform basic flows are considered with the assumption that the aspect ratio between wavelength and water depth is small. A new model is derived using the velocities at arbitrary distances from the still water level as the velocity variables instead of the commonly used depth-averaged velocities. This significantly improves the dispersion properties and makes them applicable to a wider range of water depths. Since its derivation requires no assumption on wave amplitude, the model thus can be used to describe waves with arbitrary amplitude.

Controllable Absorption and Dispersion Properties of an RF-driven Five-Level Atom in a Double-Band Photonic-Band-Gap Material

The probe absorption-dispersion spectra of a radio-frequency （RF）-driven five-level atom embedded in a photonic crystal are investigated by considering the isotropic double-band photonic-bandogap （PBG） reservoir. In the model used, the two transitions are, respectively, coupled by leading to some curious phenomena. Numerical simulations the upper and lower bands in such a PBG material, thus are performed for the optical spectra. It is found that when one transition frequency is inside the band gap and the other is outside the gap, there emerge three peaks in the absorption spectra. However, for the case that two transition frequencies lie inside or outside the band gap, the spectra display four absorption profiles. Especially, there appear two sharp peaks in the spectra when both transition frequencies exist inside the band gap. The influences of the intensity and frequency of the RF-driven field on the absorptive and dispersive response are analyzed under different band-edge positions. It is found that a transparency window appears in the absorption spectra and is accompanied by a very steep variation of the dispersion profile by adjusting system parameters. These results show that the absorption-dispersion properties of the system depend strongly on the RF-induced quantum interference and the density of states （DOS） of the PBG reservoir.

Dispersion Characteristics of the Microstrip Bend at Millimeter Wave Frequencies

The effect of the microstrip bend on the propagation characteristics of a microstrip line was investigated based on the Finite-Difference Time-Domain(FDTD)method.The dispersive characteristics of a microstrip line with a bend are quite different from that of a uniform straight microstrip line.The effect of bend discontinuity on propagation constants deceases exponentially with the distance form the corner of the bend.This can be explained by the fact that the higher order modes excited by the bend discontinuities have intrinsic properties of exponentially decay with the distance from the bend discontinuities.This effect can be negligible(less than five percent)when the distance is beyond ten times of conductor strip width.The S parameters and propagation constants comparison between unmitered and mitered bends are also presented.The proposed method which takes advantage of the FDTD algorithm and the Root Mean Square Deviation(RMSD)analysis is also an effective way for analyzing the dispersion characteristics of other planar transmission lines.

Controllable Optical Solitons in Optical Fiber System with Distributed Coefficients

We present how to control the dynamics of optical solitons in optical fibers under nonlinearity and dispersion management, together with the fiber loss or gain. We obtain a family of exact solutions for the nonlinear Schrfidinger equation, which describes the propagation of optical pulses in optical fibers, and investigate the dynamical features of solitons by analyzing the exact analytical solutions in different physical situations. The results show that under the appropriate condition, not only the group velocity dispersion and the nonlinearity, but also the loss/gain can be used to manipulate the light pulse.

A Half-Power Trace Formulas for the Generalized Jaulent-Miodek Equation

A new dispersive relation is found and a half-pow tormulas for the generalize Miodek equation under the deeaying conditions at infinity are obtained.

Cold-Test Experimental Research of an S-Band Broadband High Power CCTWT

Cold-test experiment of an S-band broadband high power coupled-cavity traveling-wave tube(CCTWT)is introduced in this paper.The dispersion characteristic,the synchronous voltage and the interaction impedance of this S-band CCTWT are measured.The experimental results are in agreement with the numerical simulation values.

The dispersion characteristics of the waves propagating in a spinning single-walled carbon nanotube

As the nano-motor becomes a mechanical reality, its prototype can be envisaged as nano-sized rotating machinery at a situation,albeit for different purposes, like that in the first half of the 20th century during which rotor dynamics has contributed toboosting machine power capacity. Accordingly, we take the benefit of hindsight to develop a classical framework of vibrationanalysis. Essentially, the equations of motion are formulated to cope with both the special carbon-nanotube properties and thefirst author’s previously developed spinning beam formalism, establishing a model satisfactorily verified by some availablemolecular dynamics (MD) data and classical spinning beam results extracted from the literature. The model is inexpensivebased on continuum mechanics as an alternative to the less-flexible MD method for simulating wave motion of the spinningsingle-walled carbon nanotube, yielding several interesting phenomena, including the fall-off and splitting of the wave charac-teristic curves and the unexpected gyroscopic phase property. Potential applications are proposed.

Topological edge state analysis of hexagonal phononic crystals

In this study,we propose valley phononic crystals that consist of a hexagonal aluminum plate with six chiral arrangements of ligaments.Valley phononic crystals were introduced into a topological insulator(TI)system to produce topologically protected edge waves(TPEW s)along the topological interfaces.The implementation of chiral topological edge states is different from the implementation of topological edge states of systems with symmetry.Unlike the conventional breaking of mirror symmetry,a new complete band with topological edge modes gap was opened up at the Dirac point by tuning the difference in lengths of the ligaments in the chiral unit cells.We investigated the dispersion properties in chiral systems and applied the dispersion properties to waveguides on the interfaces to achieve designable route systems.Furthermore,we simulated the robust propagation of TPEWs in different routes and demonstrated their immunity to backscattering at defects.Finally,the existence of the valley Hall effect in chiral systems was demonstrated.The study findings may lead to the further study of the topological states of chiral materials.

Propagation characteristics of six-core photonic liquid crystal fibers

We demonstrate a new kind of multi-core photonic liquid crystal fibers (PLCFs) which have six liquid crystal cores arrayed in the ring-type geometry and separated by the air holes. Through analyzing the structure of this kind of PLCFs, it can be found that they have the ability to resist the structure deformation. Due to the effective index of the liquid crystal can be adjusted by temperature and wavelength, the energy in the six liquid crystal cores is increased with the temperature increasing and wavelength decreasing. The effective index of the PLCFs is decreased, the effective fundamental mode area is increased and the dispersion properties are gently affected with the wavelength increasing and temperature decreasing.