Intense upconversion and infrared emissions in Er3+;Yb3+ codoped Lu2 Si O5 and (Lu0.5 Gd0.5)2 Si O5 crystals

High optical quality Lu2SiO5 (LSO) and (Lu0.5Gd0.5)(2)SiO5 (LGSO) laser crystals codoped with Er3+ and Yb3+ have been fabricated by the Czochralski method. Intense upconversion (UC) and infrared emission (1543 nm) are observed under excitation of 975 nm. The luminescence processes are explained and the emission efficiencies are quantitatively obtained by measuring the UC efficiency and calculating the emission cross section. The temperature-dependent optical properties of the crystals are also investigated. Our study indicates that Er3+-Yb3+ : LSO and Er3+-Yb3+: LGSO crystals are promising gain media for developing the solid-state 1.5 mu m optical amplifiers and tunable UC lasers. (c) 2008 American Institute of Physics.

镱、钠共掺的氟化钙晶体在1050nm的可饱和吸收作用

通过在稳定连续波运转的Yb:YAG激光器中插入不同掺杂浓度的新型钠、镱共掺的氟化钙晶体的对比性实验,证明了镱、钠共掺的氟化钙晶体在1050nm具有明显的可饱和吸收作用,从而解释了该晶体作为增益介质在该波段总是趋于自调Q运转的原因.Yb3+离子是该晶体可饱和吸收作用的主要因素,但是共掺入适当的Na离子可以明显改善晶体的调Q效果.优化共掺镱、钠离子的浓度和比例后的氟化钙晶体能够作为1050nm波段激光器的被动Q开关.

First-principles calculations of electronic structures and absorption spectra of YAlO3 crystals with F center

National Nature Science Foundation of China (Grant No. 60607015)

Damage on HfO2/SiO2 high-reflecting coatings under single and multiple Nd:YAG laser pulse irradiation

The single- and multi-shot damage behaviors of HfO2/SiO2 high-reflecting (HR) coatings under Nd:YAG laser exposure were investigated. Fundamental aspects of multi-shot laser damage, such as the instability due to pulse-to-pulse accumulation of absorption defect and structural defect effect, and the mechanism of laser induced defect generation, are considered. It was found in multi-shot damage, the main factors influencing laser-induced damage threshold (LIDT) are accumulation of irreversible changes of structural defects and thermal stress that induced by thermal density fluctuations.

单晶硅材料的1064nmNd：YAG脉冲激光损伤特性研究

作为微电子和光电子系统中普遍使用的一种结构材料，单晶硅一直是人们研究的焦点。长期以来，人们对其电学性质进行了非常深入细致的研究，却疏于对其抗击强激光辐照特性的研究。随着激光通讯和光电对抗技术的发展，对光学材料的激光破坏特性和加固技术进行研究的需求也显得越来越迫切。本文主要对单晶硅的抗激光损伤特性进行研究，研究了单晶硅材料在1064nmNd：YAG激光自由脉冲输出模式和单脉冲输出模式作用下的损伤特性，通过对两种激光作用下单晶硅损伤形貌的分析，在热效应与热力耦合模型的基础上，对单晶硅的激光损伤机制进行了探索。

Laser-induced damage of Ta2O5/S1O2 narrow-band interference filters under different 1064 nm Nd : YAG laser modes

The laser-induced damage (LID) behavior of narrow-band interference filters was investigated with a Nd:YAG laser at 1064 nm under single-pulse mode and free-running mode. The absorption measurement of such coatings was performed with surface thermal lensing (STL) technique. The damage morphologies under the two different laser modes were also studied in detail. It was found that all the filters exhibited a pass-band-center-dependent absorption and laser-induced damage threshold (LIDT) behavior, but the damage morphologies were diverse. The explanation was given with the analysis of the electric field distribution and the operational behavior of the irradiation laser. (c) 2005 Elsevier B.V. All rights reserved.

一种用于Yb：YAG激光器的波长分离膜的研制

以1030nm高反．940。980nm高透的波长分离膜作为实例，为提高该薄膜元件的波长分离效果，从膜系的优化方面做了一系列的研究。诸如采用带通滤光片的设计思想，在膜堆两侧加入了匹配层，调整膜堆的周期厚度，并用膜系设计软件对通带作进一步的优化。通过这一系列的优化设计后．利用RF双离子柬溅射工艺在BK7玻璃基底上沉积样品薄膜，并在基底背面加镀通带增透膜。结果显示，透射带在940和980nm处的透过率分别为97．73％和93．63％．反射带在1030nm的反射率为99．99％。对所制备的样品薄膜进行了激光损伤阈

Propagation properties of beams generated by Gaussian mirror resonator in uniaxial crystals

Based on the paraxial vectorial theory of beams propagating in uniaxially anisotropic media, we have derived the analytical propagation equations of beams generated by Gaussian mirror resonator (GMR) in uniaxial crystals, and given the typical numerical example to illustrate our analytical results. Due to the anisotropy crystals, the ordinary and extraordinary beams originated by incident beams generated by GMR propagate with different diffraction lengths, thus the linear polarization state and axial symmetry of the incident beams generated by GMR do not remain during propagating in crystals. (c) 2006 Elsevier GmbH. All rights reserved.

Nd：YAG激光器光栅式扫描预处理的计算模拟与优化分析

采用计算模拟的方法．研究了光栅式扫描预处理的扫描方式以及脉冲能量波动、定位误差对预处理效率的影响。研究发现。脉冲能量波动及其定位误差使预处理效率降低，同时其影响与扫描方式之间存在相互调制作用．因此可以通过选择合适的扫描方式以及扫描间隔来优化预处理流程，提高预处理效率。此外发现，光斑呈等边三角形排列时的预处理效率优于正方形。