LBO晶体上ZrO2薄膜的显微结构和光学性质

用电子束蒸发方法在三种不同取向的三硼酸锂(LiB3O5,简称LBO)晶体上沉积了ZrO2薄膜.采用分光光度计和X射线衍射技术对LBO晶体基底结构对薄膜光学性质和显微结构的影响进行了研究.实验结果表明基底结构对薄膜的显微结构和光学性质具有明显影响,即X-LBO,Y-LBO和Z-LBO上沉积的ZrO2薄膜分别沿m(-212),m(021)和o(130)择优生长,且m(021)择优取向的ZrO2薄膜具有最高的折射率和最小的晶格不匹配.     

Development in Laser Induced Extrinsic Absorption Damage Mechanism of Dielectric Films

Absorption of host and the temperature-dependence of absorption coefficient have been considered in evaluating temperature distribution in films, when laser pulse irradiates on films. Absorption of dielectric materials experience three stages with the increase of temperature： multi-photon absorption; single photon absorption; metallic absorption. These different absorption mechanisms correspond to different band gap energies of materials, which will decrease when the temperature of materials increases. Evaluating results indicate that absorption of host increases rapidly when the laser pulse will be over. If absorption of host and the temperature-dependence of absorption are considered, the maximal temperatures in films will be increased by a factor of four.     

Pinhole defects in MPCVD diamond films

Diamond films were deposited in microwave plasma chemical vapor deposition (MPCVD) method on plain silicon substrates with (100) orientation. And the pinhole defects on them were investigated by optical microscopy and scanning electron microscopy (SEM). X-ray masks were fabricated with the films deposited by us. We found the pinhole defects in the film destroyed the gold absorber. The corrosion-resistance tests conducted in 30% KOH solution under 80℃showed that the diamond films with pinhole defects have lower corrosion-resistance. In addition, the possible mechanism of the formation of pinhole defects in diamond films was discussed. And we deduced that the defects on substrates, competitive growth of multi-phase in diamond films, lattice dislocation between substrates and diamond films could be associated with the defect formation.     

ZrO2/SiO2多层膜中膜厚组合周期数及基底材料对残余应力的影响

ZrO2/SiO2多层膜由相同沉积条件下的电子束蒸发方法制备而成,通过改变多层膜中高(ZrO2)、低(SiO2)折射率材料膜厚组合周期数的方法,研究了沉积在熔石英和BK7玻璃基底上多层膜中残余应力的变化.用ZYGO光学干涉仪测量了基底镀膜前后曲率半径的变化,并确定了薄膜中的残余应力.结果发现,该多层膜中的残余应力为压应力,随着薄膜中膜厚组合周期数的增加,压应力值逐渐减小.而且在相同条件下,石英基底上所沉积多层膜中的压应力值要小于BK7玻璃基底上所沉积多层膜中的压应力值.用x射线衍射技术测量分析了膜厚组合周期数不同的ZrO2/SiO2多层膜微结构,发现随着周期数增加,多层膜的结晶程度增强.同时多层膜的微结构应变表现出了与所测应力不一致的变化趋势,这主要是由多层膜中,膜层界面之间复杂的相互作用引起的.     

Characteristics of 355 nm Laser Damage in KDP and DKDP Crystals

We present the characteristics of bulk damage induced by the third harmonic of Nd：YAG laser irradiation in KDP and DKDP crystals. Bulk damage occurs as a few or a series of pinpoints consisting of a core and the deforming zone. The results of a 1-on-1 test reveal that the pinpoint size increases with incvreasing fluence, and the pinpoint density increases exponentially with increasing fluence. The results of an s-on-1 test indicate that the pinpoint density increases gradually with laser pulse number, but the size does not grow. These results are consistent with a model in which nanoabsorbers are assumed to exist in the crystal and the initiation of damage is determined by heating them to the critical temperature.     

固体高次谐波：现象、机制及应用（特邀）

固体材料在超快强激光驱动下的高次谐波辐射是凝聚态物理、材料学、光学与光子学等学科领域的交叉研究方向。目前固体高次谐波研究已经从金属、半导体、普通绝缘体等块体材料拓展到低维纳米结构,并且在拓扑绝缘体和拓扑表面态上也成功探测到非微扰的高次谐波信号。与气相原子、分子相比,固体材料具有更高的原子密度,且固体高次谐波的产生机制更为复杂,在新型光源、材料物性和微观动力学表征等方面拥有良好的应用前景。本文主要回顾了近年来固体高次谐波的实验和理论进展,并对其机制及潜在应用进行探讨和展望。     

双折射雕塑薄膜的研究进展

倾斜沉积技术制备的雕塑薄膜是一种新型的、具有各向异性结构的薄膜材料.根据基片旋转方式的不同,可得到螺旋状、S形状、C形状、弯曲柱状等不同结构的薄膜,并且出现了晶体中的双折射现象.雕塑薄膜可以实现各向同性薄膜无法实现的光学性质,为光学薄膜的设计与制备开辟了新的途径.本文综述了雕塑薄膜的制备方法,分析了雕塑薄膜的微结构与双折射特性,并阐述了其在光学领域内的应用潜力.     

光学薄膜的分层界面散射模型

提出了一种计算光学介质膜系表面总积分散射(TIS)的理论模型。该模型认为,介质膜系粗糙的膜层界面和表面为微观结构不均匀的微薄过渡区;过渡区可用折射率为不同常量的层数足够多的均匀子层来代替,同时这些均匀子层的折射率变化满足指数函数的分布规律。利用矩阵法对积分散射的表达式进行了推导。对于电子束蒸发方法在K9玻璃上沉积的ZrO2单层膜,分层界面散射模型对积分散射的理论计算值要比非相关表面散射模型的计算值更加符合总积分散射仪的实验测量结果。     

90°反射式相位延迟器的设计

铜蒸气激光反射镜在非正入射的时候 ,两个不同的偏振态之间会产生不同的相移。通过优化设计 ,在4 90～ 5 30nm之间p、s波获得了 90°的相移 ,同时也使反射率在 99 998%以上。Ag层的厚度对于相移不敏感 ,并且当其厚度大于一定值的时候 ,对反射率没有影响。根据误差分析 ,制备薄膜时其沉积速率精度控制在± 1%以下 ,在光谱范围内能达到± 15 2 8°的相移误差 ,相移均在 5 0 4nm处附近存在有一个收敛值。折射率的变化控制在± 1%以下 ,在光谱范围内能达到± 12 77°的相移误差。最外一层厚度变化± 1% ,其相移变化达到± 5 5°,2～ 5层和 9～ 16层对相移的影响也在 0 .5°之上 ,其余各层对相移影响非常的小。使用时的入射角控制在± 1°时 ,在光谱范围内能达到± 2 .86°的相移误差。在 5 30nm附近的波段对入射角不敏感。     

ZrO2薄膜残余应力实验研究

采用ZYGO MarkⅢ-GPI数字波面干涉仪对电子束蒸发方法制备的ZrO2薄膜中的残余应力进行了研究,讨论了沉积温度、沉积速率等工艺参量对ZrO2薄膜残余应力的影响。实验结果表明：随着沉积温度及沉积速率的升高,ZrO2薄膜中残余应力状态由张应力变为压应力,且压应力值随着沉积温度升高而增大。同时用X射线衍射技术测量分析了不同沉积条件下ZrO2薄膜的微结构组织,探讨了ZrO2薄膜微结构与其应力的对应关系。