以光激射器作长度测量

激光的波长取决于下列两个因素：①经历了正常跃迁的受激原子所产生的辐射波长;②光学共振膣的两块反射镜之间的距离。因此,激光波长的粗值决定子受激原子跃迁的物理条件,而其精确的值则取决于所使用的共振腔的机械线度和光学线度。这样,调节两个反射镜之间的距离(这个距离决定了共振腔的线度)便能改变激光的波长。实验工作者藉助于各种方法,如压电效应或磁致伸缩效应,能将空腔的长度、因而激光的波长调整至选定的值,当然,这个值必然处在受激原子跃迁的正常波长范围之内。     

光电流光谱技术与原子荧光法联用测定激光波长

激光波长仪可在一定精度内测定激光波长,但在激光光谱学和激光分离同位素的应用研究中,不能保证测得的波长已与原子的某一跃迁共振。而光电流光谱技术恰好具有及时地反映这种共振的性能,激光激发原子荧光法的应用又为复杂原子谱线的认定提供准确可靠的依据。我们联用这两种技术简便快速而又准确无误地分别测定了与铀、镧原子一些非精细结构高分辨谱线中某一成分共振的激光波长。     

镁对2155.0和4310.0波长激光的共振跃迁研究

镁3 s~(21)S—3 S3d~1D双光子共振跃迁波长为4310.0A,本文报导实验中不仅观察到4310.0。A波长激光的双光子共振跃迁信号,还观察到了其信频光2155.0A波长激光的单光子共振跃迁信号,此跃迁在原子光谱中是禁戒的。通过对共振电离信号及侧向荧光辐射的分析比较,我们认为2155.0A激光的共振跃迁与镁蒸气甲Mg_2准分子的形式有关。     

应用空心阴极灯激光激发的荧光法研究高激发态镍原子的高分辨光谱

根据具有两条跃迁上能级间隔距离很大而波长差很小的原子谱线的元素在吸收满足共振跃迁的特定波长激光后可能产生波长差很大的非共振荧光线的特点,我们应用空心阴极灯激光激发荧光法,通过探测分别属于z~3D_3~0→f~3D_2和z~1D_2~0→f~1D_2跃迁的5142.77891A和5176.56337A荧光线的轮廓和线宽,间接把上述两条高分辨谱线分辨开。     

紫外激光冷却镁原子

利用反向激光与原子跃迁产生共振,可使Na和Cs原子减速。与Na和Cs原子相比,Mg原子结构对于冷却更为方便。Mg原子的部分能级示于图1。从图中可以看出,区别于Na或Cs原子的是Mg原子的基态没有精细结构,因此也就避免了光泵效应。当然有一定输出功率的与Mg原子的~1S_0—~1P_1产生共振跃迁的285.2nm的激光是必要的。     

多光子跃迁的量子理论

本文用全量子理论方法处理了多光子过程。利用Laplace变换法导出了多光子过程的跃迁几率、跃迁速率和平均跃迁几率。本文结果普遍适用于单模和多模激光作用于原子、分子的多光子共振和非共振过程。最后,以NO分子为例,给出了计算曲线。     

连续波染料激光选择性激发的钠原子双光子跃迁的观测

用氩离子激光泵浦的连续波染料激光选择性激发钠原子,观察到钠原子3s-5s态的双光子跃迁。激发波长为6022.3埃(相当于3s-5s态跃迁频率的一半)。可调谐染料激光在选定的波长范围内输出功率低于1毫瓦,带宽为0.5埃。     

铅蒸气激光器

我们利用实验室里现有的进行铜蒸气激光实验的装置,进行了Au、Ba、Pb等蒸气激光器的实验。本文主要报告Pb蒸气激光器(7229(?)波长)的实验结果。 铅原子的基态是6p~2(3p),上激光能级是第一共振能级6s~26P7s(~3p_1~0),7229(?)波长的下激光能级是6S~26p~2(~1D_2),有关能级图见图10但是,激光跃迁~3p_1~0→~1D_2是三重态到单重态的跃迁,在L-S耦     

优化有效势模型与拟谱法在碱金属原子高次谐波产生研究中的应用

结合数值参数优化有效势模型与拟谱-分裂算符方法,研究了强激光场下碱金属原子气的高次谐波产生过程.基于参数优化有效势特点对演化矩阵进行了处理,保证了演化过程中含时波函数与闭壳层轨道的正交性.选取波长为3038 nm、强度约1013 W/cm2的中红外激光场作为驱动场,计算了锂、钠、钾原子的高次谐波谱.研究了长激光脉宽下里德伯态钠原子束缚态跃迁峰对谐波产生的贡献,结果表明里德伯态与基态的共振会使低阶谐波的强度增加一个量级,验证了该方法描述含时演化过程中电子重俘获过程的可靠性.     

由原子强四波混频光共振激发Na_2产生的紫外受激辐射

用波长为５７８．７ｎｍ的激光双光子共振激发Ｎａ－Ｎａ２混合样品中的钠原子（３Ｓ→４Ｄ），在紫外区３２０～３７０ｎｍ范围内得到了四十多条受激辐射线。标识和分析的结果表明，钠原子中共振增强的四波混频光作为一个次级激发源将Ｎａ２从基态Ｘ∑＋共振激发到Ｃ１ｘ态，继而由Ｃ１ｚ向Ｘ１∑＋态跃迁产生了上述的紫外受激辐射线。     

泵浦带有弛豫振荡的固体激光器的弛豫振荡特性理论研究

对泵浦带有弛豫振荡的固体激光器的弛豫振荡特性进行了系统的理论研究，发现实际光子数的起伏同时具有自身固有的弛豫振荡频率和泵浦光的弛豫振荡频率两种分量．当两者的频率相近时，会呈现出共振加强现象．特别是当两个弛豫振荡的衰减率也相等的时候，共振现象极为强烈．PD反馈能够有效地抑制弛豫振荡．     

Using multiple mutually incoherent fiber lasers to pump a coherentsignal beam in an optical parametric oscillator

We use three-dimensional numerical modeling to show that multiple mutually incoherent lasers can be used to pump a single resonated coherent signal beam in an optical parametric oscillator (OPO). We consider as an example an OPO based on periodically poled lithium niobate pumped noncollinearly by CW Yb-doped fiber lasers. Our modeling, which neglects thermal lensing, is appropriate when the average power is kept low by chopping or pulsing the pump beams at a low duty cycle. We find that a signal beam can be produced with near-diffraction-limited beam quality and power considerably exceeding that of a single pump laser     

LD泵浦不同腔结构高效运转掺铥光纤激光器

研究了掺铥光纤激光器的不同谐振腔结构方式。使用LD泵浦,分别采用双色镜和端面反射、高反光纤光栅和端面反射以及双色镜和低反光纤光栅构成激光器谐振腔,均获得了超过Stokes极限的斜效率。其中双色镜和端面反射腔结构下获得了最高斜效率56.9%,对应的量子效率为142%。三种腔结构下,激光光谱线宽由激光器系统所采用的反射腔的光谱特性所决定。在双色镜和端面反射腔结构下,激光器在双色镜的高反带宽内随机起振,光谱较宽;在使用光纤布拉格光栅作为激光器谐振腔的高反射腔镜和低反射腔镜的情况下,激光器都获得了2 m处的窄线宽输出,线宽受限于所使用的光纤光栅的反射带宽。     

蓝紫光的腔增强空气喇曼光谱

喇曼光谱是一种无损、快速检测物质成分的方法。为了提高监测灵敏度, 对408nm波段半导体激光器的腔增强自发喇曼散射进行了研究。利用输出功率500mW、线宽0.9nm的408nm半导体激光器作激发光, 把激光耦合入共焦球面镜腔, 两面共焦球面镜的反射率分别为96.5%和99.5%, 部分激光返回半导体激光器形成光反馈, 半导体激光器与共焦腔形成共振。对装置的光反馈过程进行了探讨, 并对外腔的模式匹配和频率匹配分别进行了分析。结果表明, 共焦腔内功率达到15W, 功率增强了30倍; 用90°探测构型收集喇曼信号, 完成了空气喇曼信号检测; 1s积分时间, 获得N₂信号900个计数。此共振增强腔大大增强了喇曼散射信号, 有潜力应用于多种气体的在线检测或高灵敏度检测。     

Resonant behavior of a small aperture backed by a conducting body

The problem of an electrically small aperture in a conducting screen backed by a conducting body is analyzed. It is found that aperture-body resonances can occur for which the power transmitted through the aperture backed by a conducting body is much larger than that when the body is not present. An example is an electrically small aperture resonated by a capacitor across its midpoint. In the loss-free case, the transmission cross section of a small resonated aperture is3lambda^{2}/4piindependent of the size or shape of the aperture. For actual conductors, the transmission cross section will be increasingly reduced by conduction loss as the aperture is made smaller.     

光纤光栅布喇格波长随温度和应力的变化特性及其补偿

主要用实验数据简要叙述了光纤光栅中布喇格波长随温度和应力变化呈良好的线性关系,并介绍了一种温度补偿装置,能有效抑制光纤光栅的布喇格波长随温度的漂移。     

Some Aspects of the Design of Wide-Band Up-Converters and Nondegenerate Parametric Amplifiers

Proper design of the diode-resonating circuit is seen to be extremely important if large bandwidth is desired in a varactor-diode parametric amplifier. Cases where there is one resonance of the diode-resonating circuit at a frequency between the frequencies of the signal-input and the sideband resonances are examined in some detail. It is shown that the frequency of this intermediate resonance can greatly influence the bandwidth capabilities of an amplifier design, and the optimum frequency for such a resonance is given for upper-sideband up-converters. The optimum frequency of such a resonance is greatly different if the diode is resonated in series than it is if the diode is resonated in shunt. It is believed that the same results would also apply for lower-sideband up-converters and nondegenerate parametric amplifiers. Some upper-sideband up-converter designs were worked out and their computed responses are given including the effects of all of the parasitic elements of the diode. Bandwidths of the order of an octave are obtained. A systematic sign procedure is given for wide-band nondegenerate parametric amplifiers which use the diode parasitic resistance as the idler termination. Some designs of this type were also worked out and their computed responses (includlng effects of all diode parasitic parameters) are presented. Bandwidths as large as 33 per cent are obtained depending on the peak gain and operating frequency range.     

The tandem optical parametric oscillator

We report the theoretical analysis of a tandem optical parametric oscillator (TOPO) in which the principal OPO generates a signal which pumps a secondary OPO. The signal produced by the principal OPO is resonated in a high-Q cavity containing both nonlinear crystals. This cavity also has low Q for the signal of the secondary OPO. The two OPO's are singly resonant, since neither idler is resonated. We show that the useful output, consisting of the two idlers and the signal of the secondary OPO, can be produced with high efficiency over a large dynamic range in the pump intensity. As an example, we discuss modeling in three space dimensions of a Nd:YAG-pumped monolithic TOPO based on periodically poled LiNbO₃. This TOPO could generate three infrared wavelengths in high-transmission bands of atmospheric water vapor     

The Application of Hypercomplex Matrix Analysis to Variable Parameter Networks

The hypercomplex matrix methods developed to treat variable parameter elements are reviewed. The application of these techniques to the linear analysis of networks of variable parameter elements is demonstrated by considering a specific problem. A network containing two resonated variable capacitors separated by one-eighth wavelength of transmission line is first considered by the phase dependent admittance method. A partial treatment of the subharmonic case is given by this method to provide a physically plausible understanding of the network behavior. The complete problem is treated by the hypercomplex matrix methods. The discussion of the results illustrates how the network properties are determined from the mathematical formalism. Calculated characteristics of the two-capacitor network are given for several values of circuit parameters.