新型阵列式片状放大器全口径增益实验研究

 利用行波法对一台闪光灯泵浦、通光口径为29cm×29cm的新型高功率固体激光阵列式片状放大器的全口径平均增益进行了实验测试，在充电电压为23kV、泵浦能密度为10J/cm³的条件下，新型4×2×3阵列式片状放大器端部模块全口径平均增益为4.925%cm^-1，内部模块全口径平均增益为5.519%cm^-1。     

Modelling of a nitrogen x-ray laser pumped by capillary discharge

We performed computer modelling of a fast electrical discharge in a nitrogen-filled alumina capillary in order to discover discharge system parameters that may lead to efficient recombination pumping of soft X-ray laser with active medium created by H-like nitrogen ions. The space-time dependences of pinch plasma quantities were found by means of a one-dimensional MHD code. Time dependences of populations of all ionisation states and populations of selected energy levels of lithium-, helium- and hydrogen-like nitrogen ions were evaluated using the FLY code as a post-processor. The population inversion was found at the quantum transition corresponding to the Balmer α-line of N⁶⁺ ions and the resulting gain factor was evaluated for different capillary radii, initial pressure, electric current peaks and periods. A gain factor of 1 cm⁻¹ spanning the time interval of 1 ns was found for an optimised arrangement with capillary radius 1.5 mm, peak current 50 kA, quarter period 40 ns and filling gas pressure 0.5 kPa. It is pointed out that even higher values of the gain factor may be achieved with thinner capillaries and shorter current pulses, e.g. a gain factor of 6 cm⁻¹ is achieved if the capillary radius is 0.5 mm, peak current 56 kA, quarter period 15 ns, and filling nitrogen pressure 3.9 kPa.     

Temporal characteristics of Ti: sapphire laser pumped synchronously by bounded pulse train

A Ti: sapphire laser pumped synchronously by a bounded frequency-doubled pulse train of a pulsed mode-locked Nd : YAG laser was presented. The temporal characteristics of the laser and optimal conditions of generating stable ultrashort pulses are also given.     

Spontaneous emission from a three-level atom embedded in an anisotropic photonic crystal

We study the spontaneous emission properties of a V-type three-level atom embedded in a photonic crystal with the anisotropic dispersion relation. We show that the localized field can disappear and the diffusion field can become intense in some regions. This originates from no singularity of the density of states. The quantum interference leads to oscillatory, quasi-oscillatory or complete decay behavior of population. The complete decay can also be realized in certain condition without depending on the initial state. Received 9 April 2000 and Received in final form 1st August 2000     

百焦耳KrF激光器腔体的设计和激光实验

1990年原子能科学研究院建成一台百焦耳KrF激光器,最大能量输出达106焦耳。本文介绍激光器腔体主要结构参数的选定和激光实验。     

低温生长GaAs在Nd∶YVO4激光器中调Q特性的研究

采用一种新型的被动调Q饱和吸收体,低温生长GaAs薄膜，实现了半导体抽运Nd∶YVO4激光器的调Q运转.研究了激光器的调Q特性,调Q抽运阈值为2W.在抽运功率9.2 W时，获得的最短脉冲半峰全宽为15 ns，最大单脉冲能量为4.84 μJ，最高峰值功率为330 W，最大平均输出功率为1.16 W；脉冲重复频率在220 kHz到360 kHz之间.     

二极管泵浦准三能级板条固体激光器的优化设计

基于最大激光增益条件，分析和优化了二极管泵浦准三能级Yb∶YAG固体板条激光器的激光增益、板条的最佳光学长度和最佳宽度参数。结果表明：在低功率侧面泵浦条件下，板条增益介质的掺杂浓度和板条宽度满足一定的关系，这为研究该类激光器提供了一条有效途径，其结果可应用于其他准三能级固体激光器设计。     

Development of a nuclear spin polarizer with the optical pumping method

We have developed an optical pumping NMR system for semiconductors as an effective nuclear spin polarizer for a solid-state NMR quantum computer. The system was successfully applied to enhance ³¹P nuclear spin polarization in InP doped with Fe, and the enhancement of the ³¹P NMR signal by more than two orders of magnitude was achieved. We also observed the strong dependences of the enhancement on the helicity and the photon energy of incident light. The most effective enhancement was achieved with the helicity σ⁺ and photon energy smaller than the bandgap by 1015 meV.     

在吡啶溶液中细菌叶绿素a分子S3-S1转换过程的实时观测

采用飞秒荧光亏蚀技术研究细菌叶绿素a在吡啶溶液中的内转换过程 .我们用 40 0和 80 0nm飞秒光作为泵浦与探测光 .该研究给出了细菌叶绿素a分子的S3 S1转换过程的实时观测 ,同时观测到随后的两个弛豫过程 .细菌叶绿素a在吡啶溶液中的内转换时间为 2 2 6fs .     

Energy Pumping with Various Nonlinear Structures: Numerical Evidences

Numerical investigations are carried out on a linear structure, weakly coupled to a small nonlinear attachment. The essential nonlinearity of the attachment enables it to resonate with any of the linearized modes of the structure leading to energy pumping, i.e. passive, one-way, irreversible transfer of energy from the structure to the attachment. Different nonlinear structures (piecewise linear system, chaotic system) and efficiency of energy pumping are studied in each case in order to be able to apply it to civil engineering. As a specific application, attenuation of vibrations of a building is studied with two building models. In particular, the case of stochastic excitations is analyzed to examine if it is possible to process energy pumping when a seism occurs and an indicator of efficiency has been introduced.