与双模SU(2)相干场相互作用的Λ型三能级原子系统中光场的位相特性和原子的相干捕获

本文研究了与双模ＳＵ（２）相干场相互作用的Λ型三能级原子系统中光场位相的动态特性，证明了光场每个模的位相及两个模的位相和均保持随机分布，给出了光场两个模位相差的平均值及方差表达式，探讨了系统初态及原子－光场耦合强度对光场两个模位相差涨落的影响，并揭示了在适当的条件下，系统呈现原子的相干捕获现象．     

相位随机涨落对相干合束条纹对比度的影响

为了研究相位波动对相干合束远场特性的影响,采用傅里叶光学方法和各态历经假说,进行了相干合束远场干涉条纹对比度的理论分析,得到了相干条纹对比度的解析表达式,并数值分析了相位随机涨落对远场干涉条纹对比度的影响。结果表明,相干合束的远场干涉条纹对比度随η的增加而增加,随相位差均方根δφ的增加而减小;在给定η和δφ的情况下,参与相干合束的激光场的个数越多,远场干涉条纹对比度越大。这一结果对理解相干合成的特性具有一定的参考价值。     

迈克尔逊干涉仪在相位相干成像测量系统中的应用

传统4f相位相干成像测量技术中,利用相位物体使测量材料产生的相位变化转换为可直接观察的振幅变化,实现材料光学非线性折射率的测量。然而相位物体的厚度是固定不变的,相位延迟会随激光波长的改变而改变,测量中需要更换合适的相位物体。理论分析了不同激光波长对相位物体相移大小的影响,详细讨论了不同形状光束下相位物体的半径和相移的大小对4f相位相干成像系统灵敏度的影响。利用了迈克尔逊干涉仪中两束光的相位延迟替代传统相位物体的功能,实现了一种相位可调的相位物体。因为迈克尔逊干涉仪两束光的相位延迟连续可调,使得在不同形状光束及不同波长激光下的测量灵敏度达到最优。该方法进一步完善了4f相位相干成像测量技术,不仅解决了传统相位物体的不足,而且提高了系统测量的精度。     

双波长激光干涉移相式测量长度技术研究

研究了应用移相干涉术测量新的一等量块的方法。对干涉图像进行多幅图的采样,由移相法计算量块测量面和与其研合的辅助平晶表面的波面面形,尤其研究了在量块干涉图中有阶跃不连续的波面复原运算的原理与技术,得到表征其表面的离散波差值,并给出量块工作面长度和长度变动量的测量结果。     

Effects of laser phase drift on coherent optical CDMA

Code division multiple access (CDMA) has been proposed for use in fiber high speed point-to-point systems. Previous research into CDMA has centered on completely coherent detection, that is, when the phases of all users in the system are known or tracked. While coherent detection is a reasonable assumption in many radio frequency systems, semiconductor lasers suffer from serious phase variation that makes tracking of all phases difficult to accomplish. This paper examines the effects of phase drift on several multiuser detectors for binary phase shift keying (BPSK), as well as two detectors for binary frequency shift keying (BFSK). It is shown that when the desired user's phase can be tracked, BPSK match filtering offers better bit error rates than BFSK, and closed form solutions for the asymptotic error probabilities are derived. When there is no phase tracking, it is shown that the probability of error of the multiuser detectors approaches one half. The analysis is based on a proof of the asymptotic normality of the interference caused by even a single undesired user. All asymptotic results are for infinitely long spreading codes that can be modeled as a random sequence of plus and minus ones. Whether or not the desired user's phase is tracked, all receivers examined suffer from the near-far problem     

半导体激光器近场测量技术

讨论了确定半导体激光器传播模近场分布的一种方法。给出实际器件的测量结果,表明本方法简单、精度较高。     

Power spectrum measurement of a modulated semiconductor laser usingan interferometric self-homodyne technique: influence of quantum phasenoise and field correlation

The amplitude-phase coupling effect introduces important dynamic line broadening in modulated semiconductor laser systems. The theory of a technique allowing measurement of the broadened spectrum using a single laser is presented. The quantum phase fluctuations of the lasing field are shown to be of great importance to the photocurrent spectrum of the mixed fields. Expressions for the photocurrent spectrum, which is shown to measure the optical field modulation power spectrum, are derived. Measurement results illustrating the theory are also presented     

基于FPGA和ARM的红外图像实时显示和采集方法

介绍了一种全光纤激光相干测速雷达,其能精确测量着陆器相对星球的速度,以辅助着陆器精确着陆。介绍了激光测速雷达的测量原理和系统方案,重点介绍了测速雷达的机载飞行试验,并对实验结果进行了分析。     

激光扫描相位边缘检测方法的研究

在激光扫描检测技术中,被测件边缘信号的检测精度将直接影响到系统测量的精度.讨论了一种新的边缘检测方法,即对扫描激光束进行调制,并利用调制信号的相位突变提取边缘信号.采用该方法可使工件边缘的检测精度小于微米量级.     

基于延时自零差光相干接收机的激光器相位噪声测试系统

在相干光通信系统中,激光器相位噪声是影响接收机灵敏度的重要因素。针对相干光通信中的激光光源相位噪声测试提出并研究了表征激光器相位噪声的3个关键指标,分别是电场的功率谱密度、相位误差方差和FM噪声谱线,建立了基于延时自零差相干接收技术的窄线宽激光器相位噪声测试系统,实现了系统仿真,并对一窄线宽激光器进行了相位噪声测试,相比传统的自外差线宽测量技术,此方法在满足测试分辨率要求的同时能够更全面表征激光器相位噪声特性。