Tm3+/Yb3+共掺氧卤碲酸盐玻璃上转换发光研究

研究了Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光光谱,分析了TmO3量对Tm3+/Yb3+共掺氧卤碲酸盐玻璃上转换发光的影响机理.结果表明:在Tm3+/Yb3+共掺氧卤碲酸盐玻璃的上转换发光中,Tm3+存在较强的浓度猝灭效应.随Tm2O3含量增加,Tm3+的上转换蓝光和红光强度先增加,后降低,在0.1 mol% Tm2O3达到最大.该结果有助于进一步提高Tm3+的上转换发光效率.     

Ag-SiO2复合薄膜形貌和吸收特性的研究

通过分层镀膜的方式制备Ag和SiO2的分层结构,经过快速热退火后,Ag颗粒扩散到复合薄膜的表面附近.通过改变Ag颗粒扩散的距离(SiO2的膜厚),可很好地控制Ag颗粒在复合薄膜表面附近的大小,浓度和形貌,进而对共振吸收特性产生影响.在实验中,根据Ag颗粒扩散的长度来调节退火的时间.发现经过足够长的时间(17.5 min)后,Ag颗粒会形成平行于衬底的平面团簇.由于Ag原子在平面团簇之间容易扩散,使得Ag颗粒的粒径平均值变小并趋于某一特定的半径,且粒径分布范围变小,导致吸收谱发生蓝移,吸收带变窄,且强度增加.     

Detection of air target based on multi-fractal analysis in a laser radar

A novel approach for detecting laser radar target based on multi-fraction dimension (MFD) of laser clutters has been proposed. The fractal dimension (FD) of laser clutter and the echoes from the plan are estimated using box-counting dimension algorithm. The intrinsic difference in the spectrum of FD Dq between them is extracted and used to detect targets. Experimental results show that the method based on MFD is more reliable than that on FD and can improve the accuracy of detection.     

Optimization of peak power of passively Q-switched lasers by taking into account intracavity laser spatial distribution

The intracavity photon density and the initial population-inversion density in the diode-pumped passively Q-switched lasers are assumed to be Gaussian spatial distributions. The space-dependent rate equations are solved numerically. The key parameters of an optimally coupled passively Q-switched laser under Gaussian approximation are determined, and a group of general curves are generated for the first time. These key parameters include the optimal normalized coupling parameter and the optimal normalized saturable absorber parameter that maximize the peak power, and the corresponding normalized energy, normalized peak power, and normalized pulse width. The curves clearly show the dependence of the optimal key parameters on the parameters of the gain medium, the saturable absorber, and the resonator. In addition, the importance including the space variation is also shown. The optimal calculations for a diode-pumped passively Nd:YVO₄ laser are presented to demonstrate the use of the curves and the related formulas.     

全息图模压复制技术(Ⅲ)——模压复制及热冲压转印技术

模压复制是形成全息产品的最后一道工序,它类似凸版印刷,因而可以实现机械化大规模生产。本文介绍了平压、滚压工艺过程及所用的原材料及设备,同时还介绍了将模压全息图应用到别的载体材料上的热冲压转印技术。     

126.5 GPa准静水压下的光谱学实验

 本文介绍了作者利用国内加工的金刚石压砧装置及组建的微区光谱系统进行100 GPa（百万大气压）准静水压光谱学实验的概况，证明压力产生装置和微区光谱系统的多功能性是充分可靠的。实验中遇到的压力产生能力超过压力测量能力的事实，反映了高压光谱学实验在压力范围扩大时所遇到的挑战。文中对高压下的拉曼、发射、吸收及反射光谱的实验原理和实验方法也作了概略的介绍。