Sub-nanosecond strong pulse generated by backward Raman scattering

Hundreds picosecond strong short-wavelength pulses have been generate by a backward Raman oscillator amplifier pumped with a 10-J KrF laser from Heaven-1 MOPA system. Not only high power but also high energy laser pulses have been obtained with an energy conversion efficiency up to 17%. 640-picosecond pulse duration was observed in our experiments by a 1.5-GHz-bandwidth oscilloscope corresponding to 34 times of pulse compression rate.     

激光等离子体的电子温度对Thomson散射离子声波双峰的影响

通过对不同激光条件产生的等离子体进行Thomson散射实验诊断，发现在距靶面为150 μm的临界密度面内，离子声波双峰强度出现明显的不对称性，而且强峰的位置发生了转移：当等离子体的电子温度较高时，强峰出现在短波方向；当等离子体电子温度较低时，强峰出现在长波方向.光的拉曼散射效应对应地解释了离子声波的双峰结构、双峰强度不对称性及强峰出现的位置.建立了光的拉曼散射与电子的Thomson散射的对应关系.     

高效液相色谱法测定过氧化氢工作液中2-乙基蒽醌、2-戊基蒽醌及其氢化物

建立高效液相色谱法快速测定过氧化氢工作液中2-乙基蒽醌、2-戊基蒽醌及其氢化物含量的方法.选择ZorbaxXDB–C18色谱柱(250 mm×4.6 mm,5μm)为分离柱,以甲醇–水溶液(体积比为75:25)为流动相,流量为0.8 mL/min,柱温为40℃,紫外检测器检测,检测波长为254 nm,外标法定量.2-乙...     

一种新颖的高灵敏度光纤光栅带宽调谐机构

设计了一种由一直梁和两个半圆拱组成的开口环结构,并将均匀光纤布拉格光栅斜贴于直梁中间的表面处。对两半圆拱施加与直梁方向平行的应力作用时,光纤光栅受到线性应力场的作用,光纤布拉格光栅即转化为啁啾光纤光栅。该机构实现了光纤光栅带宽的线性调谐,线性度高达0．9982,实验结果与理论分析一致。与以往的带宽调谐机构相比,该机构具有很高的应力灵敏度,在20N力的作用下,可产生约7nm的带宽反射,灵敏度达0．34nm／N。利用环境温度对带宽调谐无影响的特性,采用带宽编码技术,研制出具有温度自动补偿特性、高灵敏度的带宽调谐装置。     

Rayleigh Scattering for An Electromagnetic Anisotropic Medium Sphere

Based on the scales theory of electromagnetic waves, the analytical expression of electrical fields inside an anisotropic medium sphere is studied. Differential scattering cross section and radar cross section （RCS） for an anisotropic spherical target are presented. The correctness of the obtained results is tested. The simulation results show that the scattering of an anisotropic sphere has the property of a dipole radiation under the condition of Rayleigh scattering. The larger the dielectric constant is, the stronger the dipole scattering is. Anisotropy in magnetism only has an effect on differential RCS. These results provide a theoretical base for the identification of anisotropic targets.     

Theoretical study on decay of the 4d core-excited states of Cs III

In a recent XUV photoabsorption spectrum of Cs Ⅲ ions by Cummings and O＇Sullivan [2001 J. Phys. B 34 199], rather large linewidths were found for the 4d^95s^25p^6 - 4d^105s^25p^5 transition which are quite in disagreement with corresponding quasi-relativistic multiconfiguration Hartree Fock （MCHF） calculation. In the present work, a detailed multiconfiguration Dirac-Fock study has been carried out to explore this discrepancy. Owing to the detailed consideration of electron correlation effects, some ‘forbidden＇ Auger decay channels, such as 4d^105s^25p^35d and 4d^105s^05p^6, would become ‘open＇. As a result, remarkable improvement of the linewidths has been obtained in our calculation. Furthermore, the theoretical Auger spectrum of the 4d^ 95s^25p^6 core-excited states of Cs Ⅲ ions is Riven in the present work.     

Excitation and decay dynamics of 1s2s inner-shell double-vacancy states of neon atoms

The photo-excitation and Auger decay processes of inner-shell double vacancy states 1s2s2p^6（1,3^S）3s3p of neutral neon atoms have been studied theoretically. Multi-configuration Dirac-Fock （MCDF） calculations have been carried out, with electron correlation effects taken into consideration. The relaxation of core and excited orbitals and configuration interaction are found to be crucial to creating the double vacancy states by single photo-absorption. The predominant decay paths for the double vacancy states turn out to be of the LLM Auger decay to 1s 2s^22p^53s（3p）, KLL Auger decay to 1s^22s2p^43s3p, and KLM Auger decay to 1s^22p^63s（3p）. They lead to further Auger decay, creating the neon ions of multiple charge states. For both double and single vacancy states the spectator type of Auger process is dominated in all the Auger decay processes. Theoretical Anger electron spectra are presented for further investigations, experimental and theoretical.     

Continuous-wave and Q-switched performance of an Yb:YAG/YAG composite thin disk ceramic laser pumped with 970-nm laser diode

Using front face-pumped compact active mirror laser （CAMIL） structure, we have demonstrated an Yb：YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave （CW） and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Q- switched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.     

钛扩散铌酸锂矩形波导中的双折射耦合对传播常数的影响

 从亥姆霍兹方程出发，得到了各向异性光波导在弱导近似下的耦合模理论。耦合系数包括偏振耦合项和双折射耦合项。并用马卡提里近似下的模式作为零级近似。用一级微扰法计算了折射率渐变分布的钛扩散铌酸锂矩形波导的传播常数。在给定参数的情况下，得到双折射项引起的传播常数的改变约为主微扰项的3%，因此双折射耦合对钛扩散铌酸锂矩形波导的性能影响不可忽略，这对设计和分析与它相关的光波导器件具有指导意义。     

斜波导喇曼振荡器

 采用斜波导的喇曼氢气池, 使泵浦激光束在波导内部传播, 增大了受激喇曼散射的作用区域。在传播过程中光束截面逐渐被压缩, 补偿因波导内壁的反射损耗而引起的功率密度下降。在一定气压范围内提高了喇曼转换的效率, 并利用波导对激光束的均匀作用, 使输出的一阶斯托克斯光光强的均匀性获得改善。