相干模表示的部分相干高斯-谢尔光束的相位-空间积

与传统的相干激光光束的评价不同,对部分相干光束质量进行评价时,不仅要反映其远场发散特性,而且还要能体现光源本身的部分相干性。根据部分相干光的相干模表示法,推导了由部分相干光源所产生光束的相位一空间积Q。与前人在相干光源情形下得到的结论相比,得出的相位一空简积Q不仅包含各个全相干模基元线性组合的贡献,而且还有来自不同的全相干模基元之间相互作用的贡献。     

复振幅光瞳滤波器的三维超分辨性能研究

超分辨技术中现有的纯振幅型或纯相位型光瞳滤波器,大部分只能实现轴向或横向超分辨而不能实现三维超分辨,三维超分辨在三维成像系统中有着重要的作用。因此为提高成像系统中的三维分辨能力,设计了一种复振幅光瞳滤波器,并对其三维超分辨性能进行了研究。详细分析了该光瞳滤波器的第一区半径和透射率对施特雷尔比、轴向和横向超分辨因子以及旁瓣能量的影响。通过一系列的模拟证明,借助于复振幅光瞳滤波器可以实现三维超分辨。该滤波器的优点是容易实现三维超分辨,且有比较高的施特雷尔比,缺点是三维超分辨的实现总是伴随着旁瓣能量的增加,但可以采用共焦扫描成像系统来加以抑制。     

Research on wavefront error of prism induced by thermoelastic distortion

To meet the design and usage requirements of the precision light beam scanner, the thermoelastic distortion of prism is detailedly analyzed by the thermal-structure coupling method, the influence of which, on the surface deformations of prism, is conclusively proved far greater than that of only the gravity load without temperature fluctuation. With the temperature fluctuation from 20 to 20.5 ℃, the strains as well as the stresses appropriately eightfold increase, which right accords with the actual results measured by Zygo Mark interferometer with the error of not over 10%. Therefore some strict temperature-controlled measures are necessary for the scanner.     

Variation of the absorption and dispersion profiles in a ladder-four-level system

A theoretical research on the variation of the absorption and dispersion profiles and population distribution of each level in a ladder-four-level system driven by two coherent fields has been made. Whether the variation occurs or not depends on the effect of quantum interference, the detuning of the upper coherent field and the separation of the two intermediate levels. A dressed-state analysis is introduced to explain the numerical results.     

Direct phase control method for binary phase-shift keying space coherent laser communication

An optical phase locking method based on direct phase control is proposed. The core of this method is to synchronize the carrier by directly changing the phase of the local beam. The corresponding experimental device and the supporting algorithm were configured to verify the feasibility of this method. Phase locking can be completed without cycle skipping, and the acquisition time is 530 ns. Without an optical preamplifier, a sensitivity of-34.4 d Bm is obtained, and the bit error rate is10^...     

Experimental research of circular incoherently synthetic aperture imaging ladar using chirped-laser and heterodyne detection

Synthetic aperture imaging ladar (SAIL) technique belongs fully coherent processing in both the time domain and space domain and has a rather high implement difficulty. To solve this problem, the concept of circular incoherently SAIL is introduced. A speckle version image of a two-dimensional (2D) letter ’E’ target is reconstructed from E-field projection data detected by a circular incoherently SAIL system. The experimental system is constructed by three subsystems using chirped-pulse laser as the light source and heterodyne detection to get the range information of the target. The reconstruction of the image and the noise effect are also discussed in detail.     

梯型四能级系统中超窄电磁感应透明与无反转增益

研究了两个光场作用下梯型四能级系统中Rabi频率及多通道辐射对电磁感应透明的影 响-在梯型四能级系统中上驱动场的Rabi频率对于超窄电磁感应透明及无反转增益的获得起 重要作用-不同的激发方式可改变电磁感应透明的位置-研究了偶极矩关联度在量子干 涉效应中所起的作用-利用缀饰态理论对数值计算结果给出了解释- 关键词： 梯型四能级系统 量子干涉效应 电磁感应透明 无反转增益     

多体制兼容相干探测卫星激光通信技术

卫星相干激光通信系统中,信号调制格式以相移键控(PSK)为主,未兼容开关键控(OOK)的相干接收。针对卫星相干光通信接收机不兼容多种调制格式的问题,实验搭建了兼容OOK以及二进制相移键控(BPSK)的相干通信接收装置。在1 Gbit/s的通信速率下,当调制格式为OOK且信号光功率为-54.6 dBm时,误码率(BER)为10^-3,接收灵敏度距离散粒噪声极限3.3 dB;当调制格式为BPSK且信号光功率为-57.95 dBm时,BER为10^-3,接收灵敏度距离散粒噪声极限4.2 dB。该多体制兼容相干接收机的结构与当前大多数相干接收机的硬件通用,且具有较高的接收灵敏度,证明了卫星相干激光通信多体制兼容技术的可行性,具有重要意义。     

卫星激光通信终端光跟踪检测的数理基础

卫星激光通信光束的传播在空间属于远场衍射,而在地面光学跟踪检验中属于近场衍射。采用菲涅耳衍射理论研究了远场衍射和近场衍射对于产生光学跟踪位置误差信号的本质上的差别并且分析了等效条件,证明了近场检验中采用卫星相对角度运动轨迹的光束扫描可以准确模拟远场相对运动,同时也得到了光斑特性和卫星抖动模拟的分析。澄清了卫星激光通信终端光学跟踪性能检验中的基本概念,具有实际指导意义。     

Analysis of detection error for spot position in fiber nutation model

The influences of nutation trail accuracy,simplification of coupling model,spot position jitter,and power variation of incident light on the detection error are analyzed theoretically.Under the condition of satisfying the requirements,the nutation radius is less than 1.13μm,the accuracy of the nutation trail is less than 0.04μm,and the detection range is[?5μm,+5μm].The nutation frequency is 160 times spot position jitter frequency and 100 times intensity jitter frequency of incident light.The analysis is of great significance for determining nutation radius and frequency in the tracking system based on fiber nutation.