横向划痕对光场调制的近场模拟

熔石英亚表面划痕对入射激光的近场调制是导致光学元件低阈值损伤的主要因素之一. 用三维时域有限差分方法研究了连续横向划痕的近场分布, 对比了尖锐截面与光滑截面场调制的差异, 着重探讨了光场调制与划痕宽深比R的关系. 研究表明: 酸蚀后的光滑截面有助于减弱近场调制, 这类划痕的R>10.0时调制较弱且相互接近, R<5.0时调制显著增强. 当R取1---3时, 亚表面的调制达最大值, 最大电场幅值为入射波幅值的4.3倍. 当R取1.0---3.5时, 缺陷附近有80%以上取样点的最大电场幅值超过入射波幅值的2倍. 随着深度的增大, 强场区具有明显的"趋肤效应": 位于划痕正下方的强场区首先往左右两侧移动, 然后移向抛物口界面以及水平界面, 同时衍生出的多条增强线诱导整个亚表面层的光场增强.     

新型大尺寸透中红外氧氟化物光学玻璃研究

红外光学玻璃是很多重要军、民用系统的关键窗口材料之一,但其高性能化、大尺寸化制备面临重要挑战。针对氟化物玻璃易挥发、抗析晶性能较差等特点,通过向含TeO2的氟铝酸盐玻璃中引入碱土金属氧化物BaO,显著降低了玻璃在熔制中的挥发,同时提高了玻璃的热稳定性。通过Raman光谱的分析,发现BaO的增加抑制了富TeO2玻璃分相,有利于碲酸盐玻璃与氟铝酸盐玻璃之间的融合,促进了玻璃网络结构的稳定。所得的氧氟化物红外光学玻璃有优异的红外透射性能,和氟化钙晶体性能对比,显示出低成本优势和更强的环境适应性。     

用TDMA法计算谐振子在强激光脉冲下的高次谐波

用含时薛定谔方程的多态展开(TDMA)方法求解含时薛定谔方程。该方法将含时波函数以基函数展开，通过求解展开系数的一阶微分方程组得到任意时刻的波函数。并将这一方法用于强激光场中谐振子的高次谐波的计算，以HCl分子为例，计算了在脉冲激光作用下高次谐波的产生和对应的激光强度、波长和脉冲宽度。     

40J激光装置研制

 报道了一台输出能量在40J量级的激光装置。该装置从星光Ⅱ激光装置分光作为光源,由放大器链、能源系统和支撑桁架等三大部分构成。对整个激光装置的模拟计算结果表明：装置的增益能力足够输出40J,B积分满足ΔB小于1.8的要求。研制了一种全腔水冷新型放大器,对其小信号增益系数和增益均匀性进行了测量,实验得出增益系数β为0.034cm ^-1,增益均匀性为91.84%。结果表明这种放大器完全能满足此激光装置的设计要求。     

Structure Characterization of HSQ Films for Low Dielectrics Using D5 as Sacrificial Porous Materials

Low-density materials, commercially available hydrogensilsesquioxane （HSQ） offer a low dielectric constant. HSQ films can be obtained by spin on deposition （SOD）. In this work, low-dielectric-constant HSQ films are prepared by using D5 （decamethylcyclopentasiloxane） as sacrificiaJ porous materials. The dielectric constant of silica films significantly changes from 3.0 to 2.4. We report the structural aspects of the films in relation to their composition after annealed at 300℃, 400℃, and 500℃ for 1.5h in nitrogen ambient and annealed at 400℃ for 1.5h in vacuum. Si-OH appears after annealed at 400℃ for 1.5h in vacuum. The results indicate that the proper condition is in nitrogen ambient. Intensity of the Sill peak increases with the increasing temperature. Fourier transform infrared spectroscopy is used to identify the network structure and cage structure of Si-O-Si bonds and other possible bonds. Dielectric constant k is significantly lowered by annealing at 350℃ for 1.5h in nitrogen ambient. The I-V and C-V measurements are used to determine the dielectric constant, the electric resistivity and the breakdown electric field.     

二次风率对分级进风燃烧室内湍流燃烧与NOx生成的影响

本文在分级进风燃烧室的热态实验装置上,测量了燃烧室内湍流燃烧的温度场和组分浓度场,研究了分级进风的流量比率即二次风率对燃烧及NOx生成的影响.得到了四组不同二次风率下燃烧室内气体温度和O2、CO2、CO与NO浓度的分布.     

Strengthened Hyper-Raman Lines with the Coherent Superposition State

High-order harmonic generations from a one-dimensional Coulomb potential atom are calculated with the initial state prepared as a coherent superposition between its ground and first excited states. When the energy difference of the two states is small, we can choose proper laser pulse such that the first excited state can be excited only to other bound states instead of being ionized. We show that only the hyper-Raman lines are observable instead of the harmonics. The energy difference of the ground and the first excited state can be deduced from the highest peak of the hyper-Raman lines. We further show that the similar results can be obtained by using a combination of two laser pulses with different frequencies interacting with the atom initially at the ground state.     

(h,ψ)-广义单调与(h,ψ)-广义凸

本文定义了几种(h,ψ)-广义凸性及(h,ψ)-广义单调性,讨论了广义(h,ψ)-方向导数与Clarke方向导数,广义(h,ψ)-梯度集与Clarke梯度集等的相关关系.利用此关系证明了这些广义凸性与广义单调性之间的相关关系,同时还揭示了这些广义凸性、单调性与通常广义凸性、单调性存在的内在联系.     

方形管道中湍流水流某些特征的激光多普勒法测量及其与圆形管道的对比

用激光多普勒测速法测量了雷诺数从4.76×10~3到4.76×10~4的矩形管道中的湍流水流。其结果与相同雷诺数时的圆形管道的流动就某些流动特征进行了对比。引人注目的是,在矩形管道内速度分布更“平坦”,且随雷诺数的增加而强烈地趋向更加均匀,湍流强度也比圆管流动的大得多。在横截面的中线上,对四种不同雷诺数所得的速度分布数据与普适的湍流速度外部定律有较好的符合。为了保持湍流的功率谱以及减小频带加宽,在测量仪器方面使用了某些技术。由Berman和Dunning所给出的有关速度梯度加宽的效应的式子也从本测量中得到了实验数据的支持。