级联三能级系统中高阶非线性效应的研究

本文采用二阶相干函数理论研究了级联三能级系统中三阶及五阶极化拍频(TPBCTS及FPBCTS)的非线性效应.通过对泵浦光为宽带及窄带情形的分析,我们发现三阶及五阶极化拍频信号的强度在时域内的变化取决于激光的统计特性和跃迁的横向驰豫率,从而在测量原子能级分裂时可以得到消除多普勒极限增宽的精度.另外,我们对信号的空间调制也进行了分析.     

V型三能级系统中高阶非线性效应的研究

本文采用二阶相干函数理论研究了V型三能级系统中三阶及五阶极化拍频（TPBVTS及FPBVTS）的非线性效应。通过对泵浦光为宽带及窄带情形的分析，我们发现三阶及五阶极化拍频信号的强度在时域内的变化取决于激光的统计特性和跃迁的横向弛豫率，从而在测量原子能级分裂时可以得到消除多普勒极限增宽的精度，另外，我们对信号的空间调制也进行了分析。     

阿秒和频相位共轭极化拍频的不对称色锁二阶相干控制

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。     

级联三能级系统中极化拍频的不对称特性

在泵浦光为窄带或宽带的情形下,我们对级联三能级系统中极化拍频的不对称特性进行了研究,发现这种不对称特性是由于光学元件色散所导致的零延时的漂移引起的.     

四能级系统极化拍频的不对称特性

在泵光为窄带或宽带的情形下,对四能级系统中极化拍频的不对称特性进行了研究,发现这种不对称特性是由于光学元件色散所导致的零延时的漂移引起的. 关键词：     

利用极化拍频光谱术研究光子回波

利用相位共轭极化拍频光谱术对Ｖ型三能级系统中的光子回波进行了研究,当抽运光束为宽带线宽且相对时间延迟〉０时,单光子四波混频对应于三脉冲受激光子回波。抽运光束为宽带线宽且相对时间延心〈０的情形与抽运光束为窄带线宽的情形类似,这种技术在测量激发态之间的能级分裂时,可得到消除多谱勒增宽的测量精度。     

受限原子极化相干缀饰四波混频光谱

研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制.     

受限原子极化相干缀饰四波混频光谱

研究了两电介质面间级联四能级系统原子的缀饰四波混频(FWM)光谱.在缀饰场的作用下FWM信号可产生Autler-Townes (AT)分裂,分裂所产生的峰及凹陷的线型及缀饰场对FWM信号的抑制与增强效应均受原子极化相干及受限原子与光场相互作用瞬态机制的调制.     

级联三能级系统中五阶极化拍频的理论研究

本文从理论上系统地研究了由于五阶极化强度间的干涉所导致的级联三能级系统相位共轭超快调制光谱学。 它对激光绝对频率的测量可达到与激光线宽同一量级的精度。 无论泵浦光束为窄带线宽或宽带线宽,它对能级差测量的总体精度仅仅取决于光学跃迁的均匀增宽,而与激光线宽和多普勒增宽无关。     

激光感生双光栅中频谱分辨率的研究

研究了用于测量两束光频差的时间延迟激光感生双光栅的频谱分辨率，确定了当泵浦光具有高斯线型时四波混频信号的产生条件，此条件通过在可调谐的窄带激光和宽带激光间的拍频实验得到证实。     

INTERFERENCE EFFECTS IN DIFFERENT FIFTH-ORDER POLARIZATIONS WITH BROADBAND NOISY LIGHT

Based on the second-order coherence function, we have studied a phase-conjugate ultrafast modulation spectroscopy due to the interference between the fifth- and fifth-order optical polarizations in cascade three-level Doppler-broadened system. It is found that the temporal behaviour of the beat signal depends on the stochastic properties of the lasers and the transverse relaxation rate of the transition. The beat signal depends on the second-order coherence function, which is determined by the laser line shape. Since different stochastic models of the laser field only affect higher than second-order coherence functions, they have little influence on the general temporal modulation behaviour of the beat signal. The cases that pump beams have either narrow band or broadband linewidth are considered and it has been found that for both cases the overall accuracy for the energy-level difference measurement is determined by the homogeneous linewidths of the optical transitions. Finally, the spatial modulation behaviour of the beat signal has also been discussed.     

NONLINEAR EFFECTS OF THIRD-AND FIFTH-ORDER ON POLARIZATION BEATS IN A FOUR-LEVEL SYSTEM

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.     

瑞利增强非简并四波混频的时域不对称性研究

基于场关联原理,采用非相干光时延四波混频法研究了瑞利增强非简并四波混频的时域特性.利用二阶场关联函数理论揭示出混频信号在时域的细微变化,发现信号展示出时域不对称性并且在τ<0时会出现振荡结构,而这种时域不对称性反映了该三阶非线性极化过程的特点.     

Fifth-order attosecond polarization beats using twin color-locked noisy lights in cascade three-level system with Doppler-free approach

Fifth-order attosecond sum-frequency polarization beat (FASPB) is studied in a cascade three level system with the phase-conjugation fourth-order coherence function theory. An improved schematic diagram of geometry, which is different from that inducing fifth-order femtosecond different-frequency polarization beat(FFDPB), is used to obtain FASPB. By analyzing the cases that pump beams have either narrow or broad bandwidth, it is found that the temporal behavior of the sum-frequency polarization beat signal depends on the properties of the lasers and transverse relaxation rate of the atomic energy-level system. Finally,the cascaded four-wave mixing (FWM) processes and the difference between attosecond and femtosecond polarization beats have been discussed, it is found that cascaded or sequential lower processes can often obscure the direct fifth-order polarization beat processes.     

激光拍频信号光子到达时间间隔特性分析

为了得到周期激光拍频信号的频率,从理论上推导了光信号相邻光子到达时间间隔满足的概率密度函数(PDF),以数值计算为基础,对周期性激光拍频信号进行详细分析,得到了稳定光强信号和周期拍频信号光子到达时间间隔PDF曲线形状的差别,从该差别中能够获取信号的拍频频率。设计了验证实验光路系统,采用多像素光子计数器(MPPC)记录光子时间,对6、8、10、12MHz拍频信号进行探测,证明了理论分析的正确性。在光子计数频率为拍频频率1/5的条件下,得到较好的实验结果,估计两光束混合效率为0.65。以暗计数噪声为限制条件,分析了该方法能够探测到的最小拍频频率为0.2333MHz。     

超快调制光谱术

简述超快调制光谱学在近向年的研究状况，其对能级差的测量精度决定于光学跃迁的均习增宽。在符合折频条件时，两独立光源拍频的差可以超出激光红宽，激光绝对频率的测量精度可以达到与激光红宽同一量级。     

Lower Order and Higher Order Entanglement in Four‐Wave Mixing Process

Possibilities of generation of lower order and higher order intermodal entanglement in four‐wave mixing (FWM) process are rigorously investigated using Sen‐Mandal perturbative technique. The investigation has revealed that for a set of experimentally realizable parameters, one can observe lower order and higher order intermodal entanglement between pump and signal modes and signal and idler modes in a FWM process. In addition, trimodal entanglement involving pump, signal and idler modes is also reported.     

简并四波混频信号的饱和效应

本文由光学Bloch方程和密度矩阵方程出发,研究了二能级系统共振型简并四波混频(DFWM)的饱和效应,给出了DFWM信号强度与泵浦光强度的函数关系.饱和泵浦光强的大小取决于纵向弛豫时间T1和横向弛豫时T2.对理论结果与相应实验进行了比较,表明二者符合得很好.