共查询到19条相似文献,搜索用时 125 毫秒
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基于孪生色锁噪声场的互相关效应,从理论上研究了倒V形(RV)四能级飞秒量级差频极化拍与极化拍中五阶非线性极化率,并提出了用一种相位敏感的方法来研究多能级原子相干造成的三光子六波混频过程.在抽泵光束为窄带末端情况下,场关联对信号和极化率的影响都很弱,在非窄带情况下,场关联会使极化强度自相干信号和极化拍信号产生关于零延时的不对称性和时域扫描上的辐射与物质失谐阻尼振荡(RDO),而极化率会产生频域扫描上的RDO振荡.参考光信号是一路传播方向和六波混频信号稍有区别的双光于非简并四波混频信号.五阶非线性响应则由享生 相似文献
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基于孪生色锁噪声场的互相关效应,从理论上研究了倒V形(RV)四能级飞秒量级差频极化拍与极化拍中五阶非线性极化率,并提出了用一种相位敏感的方法来研究多能级原子相干造成的三光子六波混频过程.在抽泵光束为窄带末端情况下,场关联对信号和极化率的影响都很弱,在非窄带情况下,场关联会使极化强度自相干信号和极化拍信号产生关于零延时的不对称性和时域扫描上的辐射与物质失谐阻尼振荡(RDO),而极化率会产生频域扫描上的RDO振荡.参考光信号是一路传播方向和六波混频信号稍有区别的双光于非简并四波混频信号.五阶非线性响应则由享生
关键词:
外差法
吸收
色散
非线性极化 相似文献
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研究了级联三能级系统中孪生色锁随机光场的相位共轭阿秒和频极化拍频(ASPB)不对称新效应。从理论上分析了自关联单光子简并四波混频(DFWM)和双光子非简并四波混频(NDFWM)信号辐射场与物质间不对等效应、混合型太赫兹失谐振荡特性,及双光子非简并共振四波混频信号的延时不对称性;同时也分析了由干涉计两臂不平衡色散效应引起的阿秒和频极化拍频信号的延时不对称性,即阿秒和频极化拍频信号的最大值相对于零延时有一个小偏移,结果表明该不对称性并这不影响阿秒和频极化拍频零差探测两偶极禁戒跃迁能级分裂的总体精度。阿秒和频极化拍频作为一种消除多普勒增宽的超快调制过程,从理论上说它可以扩展到任何两偶极禁戒跃迁能级系统。 相似文献
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针对结构中微裂纹检测难题,发展了一种闭合裂纹非共线混频超声检测方法。在对非共线混频超声检测机理分析基础上,进行了结构中疲劳裂纹混频非线性超声检测实验。对有无裂纹试件中检测信号进行了滤波和时频分析,结果表明,可根据信号滤波后时域波形中是否存在明显的混频波包或时频分析中是否存在明显的和频分量,实现有无闭合裂纹的判识;通过移动激励探头的位置,控制两列入射声波在试件中的交汇位置,实现试件中不同深度位置的混频非线性检测。并根据测得的混频非线性系数沿试件深度方向上分布,实现了闭合裂纹沿深度方向上长度的测量。研究工作为结构中微裂纹定量评价做了有益探索。 相似文献
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研究了受强缀饰场作用的五能级原子系统所产生的多波混频共存特性.研究发现,通过调节激光束方向,沿同一方向出射的八波混频、双缀饰四波混频和单缀饰六波混频信号因共用能级的原子相干产生而出现竞争现象,通过控制缀饰场减弱四波混频和六波混频信号强度,可以达到增强八波混频信号的目的.还对级联和并联两种不同缀饰方式下双缀饰四波混频过程的差别进行了详细分析.
关键词:
双缀饰四波混频
单缀饰六波混频
八波混频
抑制增强 相似文献
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本文理论分析和实验测量研究了微波相位噪声对里德堡原子天线微波混频信号的影响。通过研究微波混频信号的相位噪声项,建立在信号场中加入相位噪声后微波混频信号强度变化的理论模拟图。实验基于室温铯原子气室中里德堡原子电磁感应透明光谱,实现里德堡原子■态的电偶极跃迁,得到频率13.806 057 GHz与13.806 000 GHz的微波场混频信号。同时,对混频信号强度的参数依赖关系进行研究。经实验发现,基于里德堡原子天线微波混频信号强度与参考场的功率有关,优化功率参数条件下,参考场可以实现约20 d B的混频信号增强;当参考场调控里德堡原子达到微波混频效率最大时,在信号场中加入相位噪声,会导致混频信号强度的显著降低。 相似文献
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本文研究了缀饰原子系统中的双光子共振非简并四波混频.理论上我们研究了多普勒增宽的四能级系统中耦合光场对双光子共振非简并四波混频的影响,发现加入强耦合场后,非简并四波混频频谱出现Autler-Townes分裂;在不同双光子共振失谐时,由于量子干涉双光子共振非简并四波混频的信号能够被抑制或增强.实验上我们在Ba原子蒸汽中,通过引入基态6s2和自电离里德堡态6pnd之间的原子相干证实了该现象.本方法提供了一种不仅可以测得共振频率和横向弛豫,而且可以测得两个高激发原子态之间的跃迁的偶极矩阵元的新的光谱学工具. 相似文献
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Strong anticipation has emerged as a new framework for studying prospective control. According to earlier theories of prediction, anticipatory behavior rests on temporally local predictions from internal models. Strong anticipation eschews internal models and draws on the embedding of an organism in its environment. In this formulation, behavior is sensitive to the non-local temporal structure of the environment. We present initial evidence for strong anticipation in a synchronization task with tapping as the behavior. Participants were instructed to synchronize, to the best of their abilities, with a (unpredictable) chaotic signal. Our data suggest a close relationship between the long-range correlations of the chaotic signal and the long-range correlations of the synchronization behavior. 相似文献
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Turbulence induced changes in spectrum and time shape of fully coherent Gaussian pulses propagating in atmosphere 总被引:1,自引:0,他引:1
Propagation of fully coherent pulses with Gaussian spatial distribution through turbulent atmosphere is studied. Turbulence induced changes in spectrum of propagated pulse and its effect on temporal behavior of the signal is discussed and has been showed that signal is widened in time domain as propagating in turbulent atmosphere. It is also proved that various points in observation plane experience different effects. 相似文献
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脉冲激光光热失调技术 总被引:4,自引:0,他引:4
将脉冲激光作为加热光引入光热失调测量技术中,提出了脉冲激光光热失调测量技术,介绍了其基本原理,分析了脉冲激光光热失调测量技术用于测量光学薄膜微弱吸收的可行性.实验以532 nm的高反射光学薄膜为样品,采用波长为632.8 nm的探测光,研究了脉冲激光光热失调技术信号振幅的时间特性以及最大信号幅值与样品表面加热光能量密度、加热光斑与探测光斑相对位置的变化关系.研究结果表明,光热信号随时间先增大后减小,而随表面加热光能量密度的提高而增大,当样品表面加热和探测光斑重合时光热信号最大. 相似文献
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NONLINEAR EFFECTS OF THIRD-AND FIFTH-ORDER ON POLARIZATION BEATS IN A FOUR-LEVEL SYSTEM 总被引:1,自引:0,他引:1
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We have employed second-order coherence function theory to study the nonlinear effects of third-and fifth-order on polarization beats in a four-level system (TPBFS and FPBFS). It is found that the different temporal behavior of the beat signal in TPBFS and FPBFS depends on the stochastic properties of the lasers and transverse relaxation rate of the transition. We have considered the cases that pump beams have either narrow band or broadband linewidth and found that for both cases a Doppler-free precision can be achieved in the measurement of the energy-level difference between two excited states which are dipolar forbidden from the ground state. We also discussed the spatiall modulation behavior of the beat signal. 相似文献
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Siltanen S Lokki T Tervo S Savioja L 《The Journal of the Acoustical Society of America》2012,131(6):4606-4614
Reflections at rough surfaces change the temporal structure of the reflected signal. This paper shows how to incorporate this temporal behavior in geometric room acoustics modeling. Specifically, a beam tracer is used for calculating the image sources and reflection paths. The roughness of the surfaces is taken into account in post-processing. A single reflection is assumed to distribute the energy according to an exponential function in time based on Biot's rough surface modeling theory. Multiple reflections are modeled with convolutions of exponential functions which are approximated as gamma functions. 相似文献