模拟退火算法在无端偏振控制器中的应用

构造了由四个相移范围在0~2π的电光晶体波片组成的偏振控制器,利用模拟退火法作为其反馈控制算法.仿真计算表明,该偏振控制器是无端的,在较优的控制参量下,其输出的偏振态是稳定的,光强波动小于1%.对于四波片偏振控制器,模拟退火算法的控制参量研究表明,为得到较佳的控制效果,可把内外循环次数各限制为3次,以减少处理器时间;其初温T0应取在0.1附近;温度更改常数p宜取在0.2左右;状态产生常数s对输出的稳定性影响最大,仿真说明设在 0.005~0.01间为好.     

光纤中偏振稳定控制的实验研究

研制了一种偏振稳定系统,可以使偏振态(SOP)保持稳定输出,而且可以是任意需要的偏振态.实验中扰偏器以不同变化频率、各种相位幅度的信号变化,稳定器对其进行偏振稳定实验.对于相位幅度为π/2的扰偏信号,进行稳定的变化频率可达8 kHz.稳定耗时分析表明,有71%的时间耗在偏振控制器的响应时间上,而稳定算法及数据处理仅占总耗时的8%.     

两偏振态测量偏振相关损耗

基于具有偏振相关损耗和双折射的密勒矩阵洛伦兹变化特性,提出了一种测量偏振相关损耗的新方法.证实了测量偏振相关损耗取决于密勒矩阵的第一列元素.提出了一种实用的测量方法.新方法对于偏振相关损耗的测量只需要两个输入偏振态,因此具有测量速度快和测量误差小的优点,实验的测量结果证实了该方法的可靠性.     

非线性偏振旋转中偏振控制器方位角的研究

提出一种基于Jones矩阵的非线性偏振旋转锁模光纤激光器数值模型, 对偏振控制器波片方位角的描述具有物理意义清晰的优点. 数值仿真得到均方根宽度为0.28 ps的超短脉冲, 时域对称且振幅稳定. 搭建了非线性偏振旋转锁模光纤激光器, 系统可以自启动, 得到了重复频率为67.35 MHz的锁模脉冲输出. 数值仿真和实验结果都表明偏振控制器两个波片的方位角α₁和α₂都具有周期性, 周期分别为180°和90°. 由于随机双折射的影响, 实验测得的波片方位角调谐范围比数值仿真的结果小, 这一点通过在数值仿真模型中加入随机双折射的作用而得到证明.     

在线单模光纤偏振控制器研究

利用Ｐｏｉｎｃａｒｅ球理论首次全面分析了在线全光纤偏振控制器。结果发现该偏振器可以有八种不同路径，实现任意偏振态之间的转化，最后通过实验验证了其工作性能。     

偏振模色散的偏振主态旋转补偿法

提出一种用以补偿一阶偏振模色散的方法通过理论分析,说明了使用偏振分离器和加入光学延迟来抑制光纤中的PMD的方法以及其存在的由于延迟偏差造成的过补偿或欠补偿由理论分析可知,通过调整输入信号偏振态的方向,可以有效改善补偿效果模拟实验证明了该方法的可行性.     

偏振态调制的偏振无关干涉型光纤传感器

针对低双折射光纤双束干涉型传感器的两臂偏振态随机变化引起的信号衰落提出了一种新型的光纤传感器结构。通过在双束干涉仪的一臂中加入适当的对光波偏振太的高尖三角波或正弦波调制的偏振制，可以在干涉中见度略有降低的情况下消除偏振衰落的影响，实现偏振无关的干涉型光纤传感器。     

偏振态对激光相干合成的影响

为了研究光束相干合成中偏振态的特性,取理想矩形光束进行模拟分析。通过改变偏振态的退偏率、偏振态夹角、参与合成的子束数目等,观察光场在远场叠加的合成效果。讨论了这些因素对远场合成效果的光强分布、峰值功率密度、光束质量因子等的影响。模拟结果显示:当退偏率小于10%、偏振态夹角小于18时,合成后光束质量因子小于1.1。     

动态偏振控制器的复位分析与实现

利用琼斯矩阵分析了适合高速应用的四通道挤压光纤型偏振控制器的复位原理,根据复位原理设计了以两通道为主延迟器,另两通道为辅助复位延迟器的复位方案,并以40Gb/s的PMD补偿系统为实验平台进行了验证,反馈信号及四通道控制电压和时间的关系曲线表明复位效果良好且复位未对PMD补偿产生不良影响。     

偏振态对激光相干合成的影响

为了研究光束相干合成中偏振态的特性,取理想矩形光束进行模拟分析。通过改变偏振态的退偏率、偏振态夹角、参与合成的子束数目等,观察光场在远场叠加的合成效果。讨论了这些因素对远场合成效果的光强分布、峰值功率密度、光束质量因子等的影响。模拟结果显示：当退偏率小于10%、偏振态夹角小于18时,合成后光束质量因子小于1.1。     

Dirac粒子的正-反粒子自由度和正-反粒子量子数

对Dirac粒子引进了正 反粒子自由度和相应的内部τ空间的算子,把γ矩阵分解成自旋σ算子和正 反粒子τ算子;Dirac方程的解出现了正 反粒子量子数;正 反粒子变换是Dirac粒子的哈密顿量的反对称变换,Dirac粒子负能态能量的负值来自正 反粒子量子数的负值;γ矩阵这种分解是处理物理相互作用的需要. he particle-antiparticle degrees of freedom and the corresponding intrinsic space are introduced to study the dynamical symmetry of the Dirac particle. As a result, the particle-antiparticle quantum number appears naturally and the Dirac particle has five quantum numbers instead of four. An anti-symmetry of the Dirac Hamiltonian and a dual symmetry of its eigen functions are explored. The operator of the Dirac equation in central potentials is found to be the analog of the helicity operator of ...     

Quantum Mechanics of Systems with a Nonenumerable Number of Degrees of Freedom

Is has been shown that the quantum theory of systems with an infinite nonenumerable number of degrees of freedom is incompatible with the assumption about the continuity of the space of indices of degrees of freedom: in this case, a discrete topology on the space of indices is required. This is illustrated by the example of field systems.     

Degrees of Freedom of a Time Series

We give a formal proof that if f is a smooth dynamics on a d-dimensional smooth manifold and is an ergodic and exact dimensional measure with Hausdorff dimension dim >d–1, then the number d of degrees of freedom of the dynamics can be recovered from the observation of an orbit. We implement, with this purpose, an algorithm based on the analysis of the microstructure of . We show how a correct estimation of d permits the computation of the Liapunov spectrum with a high accuracy avoiding the issue of the spurious exponents.     

Vibrational Dissipative Systems with Two Degrees of Freedom

Doklady Physics - Forced linear oscillations of dissipative mechanical systems with two degrees of freedom under the action of time-periodic forces are considered. The Lagrange equations are...     

Spatial Degrees of Freedom in Everett Quantum Mechanics

Stapp claims that, when spatial degrees of freedom are taken into account, Everett quantum mechanics is ambiguous due to a “core basis problem.” To examine an aspect of this claim I generalize the ideal measurement model to include translational degrees of freedom for both the measured system and the measuring apparatus. Analysis of this generalized model using the Everett interpretation in the Heisenberg picture shows that it makes unambiguous predictions for the possible results of measurements and their respective probabilities. The presence of translational degrees of freedom for the measuring apparatus affects the probabilities of measurement outcomes in the same way that a mixed state for the measured system would. Examination of a measurement scenario involving several observers illustrates the consistency of the model with perceived spatial localization of the measuring apparatus.This work was sponsored by the Air Force under Air Force Contract FA8721-05-C-0002. Opinions, interpretations, conclusions, and recommendations are those of the author and are not necessarily endorsed by the U.S. Government.     

六自由度电磁探测的快速数值算法

提出一种六自由度电磁探测的快速数值算法,对500 mm×500 mm×500 mm范围内的空间磁场进行数值仿真,并与电流环近似算法和严格算法进行比较,归一化计算时间比为10⁶:70:1,结果表明该算法可行可靠.最后讨论怎样有效地克服螺线管线圈的有限长效应引起的偏差,从而进一步提高探测系统的探测精度及稳定性.