Method of Self-Mixing in the Spectroscopy of Quasielastically Scattered Laser Radiation

Interaction of a semiconductor laser with its self-radiation quasielastically scattered in the environment is considered. It is established that at small coefficients of coupling of the laser with the scattering medium the spectral density of the power of an optoelectronic signal in the laser faithfully reproduces the shape of the scattered-radiation spectrum at the Doppler-shift frequencies. This makes it possible to measure the spectrum with a resolution characteristic for optical homodynation by recording the optoelectronic signal.     

高能X光照相CCD成像系统的模糊效应

 指出了景深、可见光衍射、辐射输运是CCD图像接收系统模糊效应的3个影响因素。用MCNP方法研究了转换屏内的辐射输运,给出了不同入射光子能谱和转换屏厚度下转换屏内能量沉积随半径的变化关系。结果表明:能量沉积随转换屏厚度的增加而线性增加;辐射输运引起的模糊与光子能谱有关,但硬化谱引起的模糊随转换屏厚度的变化小于非硬化谱;转换屏内的辐射输运是CCD图像接收系统模糊效应的主要影响因素;辐射输运引起的模糊和高斯模糊是不同的。     

自旋-轨道耦合系统中的自旋流定义

通常的自旋流定义在描述自旋-轨道耦合系统中的自旋输运是不完整的与非物理的。文章作者提出在这类系统中自旋流的恰当定义。新定义的自旋流克服了通常定义下的本质缺点，可通过实验直接观测。     

氯原子光诱导能级移动和增宽

应用半经典的微扰论方法计算出了氯原子光诱导能级移动和增宽，其大小与光强成正比。光频率为41018cm^-1时，氯原子初态3p^52P3/2^0和3p^52P1/2^0在非共振情况下，光移动分别为67．6和26．9MHz/Wμm^-2。当激光频率V接近3P^52P3／2^0→4s^2P3/2的跃迁频率时，氯原子基态3p^52P3/2^0的|MJ,MI>=|-1/2,3/2>→|1/2,3/2>超精细ESR谱线发生近共振频率光移动，大小量级为0．1MHz/Wμm^-2，能级增宽一般远小于光移动。     

ZnSe: Fe2+中的动态Jahn-Teller效应和远红外光谱的研究

推导了3d^4/3d^6离子基态5D在立方晶体场，自旋－轨道耦合和动态Jahn-Teller效应作用下的哈密顿矩阵，并用对角化该哈密顿矩阵的方法研究了Fe^2+在ZnSe中的远红外光谱，理论计算与实验符合得好，研究表明，在ZnSe:Fe^2+中，比晶体场理论分析多出的分裂谱线是Fe^2+与ZnSe晶格间的动态Jahn-Teller效应引起的，还预测了其它Jahn-Teller效应分裂谱，所推导的哈密顿矩阵对研究3d^4/3d^6离子在立方晶体中的精细光谱，电子顺磁共振谱和动态Jahn-Teller分裂都是有用的。     

Correction of self-absorption spectral line and ratios of transition probabilities for homogeneous and LTE plasma

Expressions for fundamental spectral line parameters are reported for Gaussian and Lorentzian shape profiles for homogeneous plasma at equilibrium in presence of the self-absorption. These expressions for Lorentzian profiles are applied to the determination of the ratios of transition probabilities and the ratios of optical thicknesses by a new method that we propose in this article. The self-absorption is computed by spectral line profiles with a Simplex algorithm program fitting. Applications to some experimental lines illustrate the appropriate corrections.     

Size dependence of self-diffusion in the hard-square lattice gas

A striking size dependence of the mean-square displacement of diffusing particles in the two-dimensional lattice gas of hard squares has been observed by Monte Carlo simulation. It is shown that the size effect is due to the formation of a stable cage structure in small lattices when the particle concentration is high. The formation of cages is governed by a new type of percolation problem related to bootstrap percolation.     

125m Te (109.3 keV) stimulated emission and gamma lasers

Summary Proceeding from the drastic discrepancy between experimental data and theory, we show (contrary to other authors) that the relations between the Einstein's coefficients are true for transitions from any of the excited levels and theground state of the quantum system only. The relations connecting those coefficients are derived for transitions betweenany two states; the corresponding cross-sections are calculated and it is shown (contrary to other authors) that the stimulated emission cross-section may be large enough for the creation of gamma lasers. The new relation for Einstein's coefficients (and the corresponding cross-sections) are fundamentally different from those known so far (74 years after Einstein). The results are compared with experiment and the coincidence is very good. These investigations can lead to progress in the study of physical processes in star atmospheres. The author of this paper has agreed to not receive the proofs for correction.     

光致折射效应中空间电荷场建立过程的研究

本文推导了包含自衍射及非线性吸收影响、用以描述空间电荷场建立过程的微分方程组,阐明了周期性的空间电荷场与光强干涉条纹之间的相位差在建立过程中所起的作用,并推导了描述条纹倾斜和弯曲的微分方程。通过数值计算找到了硅酸铋(BSO)晶体中能量转移的规律,讨论了材料特性对过程快慢的影响,提出了用CW激光来探讨瞬态过程快慢的可能性。     

微微秒超短脉冲的光学压缩

在研究了短光纤(L～L_w)中受激喇曼散射的斯托克斯脉冲对基波脉冲能量箝位效应的基础上进行了脉冲压缩实验。以高泵浦功率(P=1600W)注入长度为8.95m绿光单模光纤中,采用双光程的光栅对压缩结构,并引入空间频率窗口滤除自相位调制光谱的非线性啁啾部分,将40ps的锁模Nd:YAG倍频光脉压缩至<5ps。