Pupil design based on Fisher information optimization to extend field depth in practical optical system

<正>Wavefront coding(WFC) is used to extend the field depth of an incoherent optical system by employing a phase mask on the pupil.We uses a Fisher information(FI) metric based optimization method to design a phase mask by taking the modulation transfer function(MTF) of the practical optical system into consideration. This method can modulate the wavefront so that the point spread function and optical transfer function are insensitive to the object distance.The simulation results show that the optimized phase mask based on the proposed method can further improve the defocusing image quality while maintaining the focusing image quality.     

多阵元光纤相干列阵的理论与实验研究

基于Fraunhofer衍射理论,建立了六角形相干列阵远场分布的理论模型,采用Strehl比和能量集中度作为评价参数,分析了列阵排列方式、振幅、填充因子对远场分布的影响.并由爬山法相位控制技术和六棱台合束器,构建了七阵元光纤相干列阵实验系统.在066填充因子情况下,获得了Strehl比为070、能量集中度为040七阵元合成光束,以及获得了能量集中度分别为045和018的二阵元线阵和四阵元矩形阵合成光束.     

Preserving Coherence of Coherent State Studied via Weyl-Wigner Correspondence

By means of the Weyl correspondence and the explicit normally ordered expression of the Wigner operator we convert the time evolution equation of coherent states, governed by some Hamiltonian operators, into seeking for consistent solution of a set of evolution equtions of classical variables which can meet the requirment that an initial coherent state remains coherent all the time.     

Mean-Field Dynamics of a Two-Mode Bose-Einstein Condensate Subject to Decoherence

We discuss the dynamics of Bose-Einstein condensates in a double-well potential subject to decoherenee （or particle loss）. Starting from the full many-body dynamics described by the master equation, an effective Gross- Pitaevskii-like equation is derived in the mean-field approximation. By numerically solving the GP equation, we find that macroscopic quantum self-trapping disappears for strong decoherence, while generalized self-trapping occurs under weak decoherence. The fixed points have been calculated, and we find that an abrupt change from elliptic to an attractor and a repeller occurs, reflecting the metastable behavior of the system around these points.     

From the Thermo Wigner Operator to the Thermo Husimi Operator in Thermo Field Dynamics

Using the thermo entangled state representation and based on the thermo Wigner operator we first introduce the thermo Husimi operator, which turns out to be a projective operator of the thermo squeezed coherent state, therefore the positive definite property of Husimi distribution function can be insured. In addition, we find the use of the thermo Husimi operator in simplifying the form of master equations.     

Coherent Beam Combining of Two Fiber Amplifiers Seeded by Multi-Wavelength Fiber Laser

Multi-wavelength seed laser can mitigate stimulated Brillouin scattering （SBS） and improve the output power of the narrow-linewidth fiber amplifier. In this present study~ coherent combining of two fiber amplifiers seeded by a multi-wavelength laser is proposed and demonstrated using stochastic parallel gradient descent （SPGD） algorithm. The long-exposure visibility of the far field interference pattern is increased from 0.15 to 0.97 when the system evolves from open-loop to closed-loop. The feasibility of coherent combining of fiber amplitlers seeded by multi-wavelength seed laser is validated.     

DNA分子电输运特性的相干隧穿研究

把DNA分子的碱基堆积相互作用视为多个单势垒的组合,电荷逐级隧穿随电压变化的势垒,利用相干隧穿理论计算了8 bp和30 bp的均匀序列DNA分子两端在硫化和非硫化情况下的伏安特性曲线,得到了与实验一致的结论.     

遥控副载波信号的软件解调方法

介绍了一种适合于突发模式下的PSK信号遥控副载波解调方法,其目的是对于突发副载波信号接收时实现快速可靠的捕获,并进行载波同步和位定时同步。文中设计的解调器是有别于传统解调器的全数字接收解调器,利用软件无线电的思想用软件方法实现解调,介绍的Viterbi载波同步算法和Gardner位定时同步算法结构简单,易于利用数字硬件实现,仿真结果也验证了此解调算法的可行性和有效性。     

基于高效形态滤波新算法的AM解调

形态滤波在软件无线电中用于解调AM信号,效果显著。文章针对形态算法解调AM信号,提出了新的“增量”开、闭快速形态算法,推导出新算法的实时表达式,论述了新算法在AM解调中结构元素的选取规则。通过与传统形态滤波算法比较,显示出新算法在AM类信号软件解调应用中的效率提高极大。实验仿真,验证了该方法对AM类信号的解调具有与传统算法同样良好效果,抗干扰性强,适合现有软件无线电的应用。