Study of Al2O3/MgF2 HR coatings at 355 nm

With the present work we tried to study the effective methods to improve the laser-induced damage threshold (LIDT) and reflectance of HR coatings at 355 nm. The work presented in this paper wits part of an ongoing study about vacuum annealing. It was dedicated to study the effects Of Vacuum annealing with different temperature gradients on the structure, optical properties and laser-induced damage threshold (LIDT) of 355nm Al2O3/MgF2HR coatings. A number of samples were prepared by electron beam evaporation using the same deposition process with an optimal deposition temperature of 280 degrees C. After deposition, samples were annealed in the coating chamber for 3 h with different temperature gradients. Morphologies of the samples were observed by Leica-DMRXE. Microscope, Structure of the samples had been characterized by X-ray diffraction (XRD). Transmittance and reflectance of the samples were measured by Lambda 900 Spectrometer, The LIDT of the samples was measured by a 355 nm Nd:YAG laser with a pulse width of 8 ns. It was found that the temperature gradient of vacuum annealing had significant effects on the morphology, structure, absorption, and LIDT of the samples, (c) 2005 Elsevier Ltd. All rights reserved.

Statistical approach to bulk inclusion initialized damage in films

In experiments, we have found an abnormal relationship between probability of laser induced damage and number density of surface inclusion. From results of X-ray diffraction (XRD) and laser induced damage, we have drawn a conclusion that bulk inclusion plays a key role in damage process. Combining thermo-mechanical damage process and statistics of inclusion density distribution, we have deduced an equation which reflects the relationship between probability of laser induced damage, number density of inclusion, power density of laser pulse, and thickness of films. This model reveals that relationship between critical sizes of the dangerous inclusions (dangerous inclusions refer to the inclusions which can initialize film damage), embedded depth of inclusions, thermal diffusion length and tensile strength of films. This model develops the former work which is the statistics about surface inclusion. (c) 2006 Elsevier B.V. All rights reserved.

Surface morphology and properties of zirconia thin films prepared at different deposition rates

ZrO2 thin films were prepared on BK7 glass substrates by electron beam evaporation deposition method. The influence of deposition rate varying from 1.2 to 6.3 nm s(-1) on surface morphology and other properties of ZrO2 films were examined. With increasing deposition rate, the surface defect density increased. The decrease in half width at full maximum in X-ray diffraction pattern with deposition rate indicates an increase in crystal dimension with increasing deposition rate. Electron beam deposited ZrO2 films are known to be inhomogeneous. From the change of the peak transmittance value, it can be deduced that the inhomogeneity of ZrO2 films strengthened gradually with increasing deposition rate. The type of surface defects changed from nodules to craters when the deposition rate was high enough.

Y2O3 stabilized ZrO2 thin films deposited by electron beam evaporation: Structural, morphological characterization and laser induced damage threshold

Four kinds of Y2O3 stabilized ZrO2 (YSZ) thin films with different Y2O3 content have been prepared on BK7 substrates by electron-beam evaporation method. Structural properties and surface morphology of thin films were investigated by X-ray diffraction (XRD) spectra and scanning probe microscope. Laser induced damage threshold (LIDT) was determined. It was found that crystalline phase and microstructure of YSZ thin films was dependent on Y2O3 molar content. YSZ thin films changed from monoclinic phase to high temperature phase (tetragonal and cubic) with the increase of Y2O3 content. The LIDT of stabilized thin film is more than that of unstabilized thin films. The reason is that ZrO2 material undergoes phase transition during the course of e-beam evaporation resulting in more numbers of defects compared to that of YSZ thin films. These defects act as absorptive center and the original breakdown points. (c) 2006 Elsevier B.V. All rights reserved.

制备工艺条件对薄膜微结构的影响

用不同的方法在石英玻璃，YAG晶体，K9玻璃和LiNbO3晶体等几种衬底上制备了ZrO2，HfO2和TiO2薄膜。HfO2薄膜利用电子束蒸发（EB）、离子束辅助（IAD）和双束离子束溅射（DIBS）三种方法沉积。对其中的一些样品进行了不同温度下的退火处理，对所有的样品进行X射线衍射（XRD）测试，以获得不同条件下得到的薄膜的晶相及晶粒尺寸等的微结构参数。实验结果表明，薄膜的晶相结构以及晶粒尺寸强烈地依赖于沉积过程的各种技术参数，如衬底的种类、沉积温度、沉积方法和退火温度。利用薄膜表面扩散以及薄膜成核长大热

Influence of different post-treatments on the structure and optical properties of zinc oxide thin films

Zinc oxide (ZnO) films with c-oriented were grown on fused quartz glass substrates at room temperature using dc reactive magnetron sputtering. The as-grown films were annealed at 700 degrees C in air and bombarded by ion beam, respectively. The effects of post-treatments on the structural and optical properties of the ZnO films were investigated by X-ray diffraction (XRD), photoluminescence (PL), optical transmittance and absorption measurements. The XRD spectra indicate that the crystal quality of ZnO films has been improved by both the post-treatments. Compared with the as-grown sample, both annealed and bombarded samples exhibited blueshift in the UV emission peaks, and a strong green emission was found in the annealed ZnO film. In both optical transmittance and absorption spectra, a blueshift of the band-gap edge was observed in the bombarded film, while a redshift was observed in the annealed film. (c) 2004 Elsevier B.V. All rights reserved.

Influences of CO2 laser irradiation on the structure and photoluminescence of zinc oxide thin films

CO2 laser irradiation experiments on ZnO thin films are reported. The structural, optical, luminescent and vibrational properties of the samples were investigated by X-ray diffraction (XRD), transmittance, photoluminescence (PL) and Raman measurements. XRD results show that the crystalline of the irradiated films was improved. The (002) peaks of irradiated ZnO films shift to. higher 20 angles due to the stress relaxation in the case of laser beam irradiation. From optical transmittance spectra, all films exhibit high transmittance in the visible range, the optical band edge of irradiated films showed a redshift compared with that of as-grown films. Compared with the as-grown films, the photoluminescence emission (in particular the relative intensities of visible emissions) intensities of irradiated samples enhanced. In the Raman scattering spectral both the A I. and E modes exhibited slight Raman blueshift. (c) 2005 Elsevier B.V. All rights reserved.

ZnO : Zn phosphor thin films prepared by face-to-face annealing

ZnO:Zn phosphor thin films were prepared by face-to-face annealing at 450 degrees C in air. The effects of the face-to-face annealing on the structural and optical properties of the ZnO films were investigated by X-ray diffraction (XRD), photoluminescence (PL), optical transmittance and absorption measurements. Measurement results showed that the crystal quality of ZnO films was improved by face-to-face annealing. Both UV light emission and visible light emission were enhanced compared to those of open annealing films. The UV emission peak was observed to have a blueshift towards higher energy. The optical band-gap edge of as-annealed films shifted towards longer wavelength. (c) 2005 Elsevier B.V.. All rights reserved.

不同沉积参量下ZrO_2薄膜的微结构和激光损伤阈值

ZrO2采用X射线衍射(XRD)技术分析了不同充氧条件和沉积温度对ZrO2溥膜组成结构的影响，并对不同工艺下制备的薄膜的表面粗糙度和激光损伤阈值进行了测量。结果发现随着氧压的升高，ZrO2溥膜将由单斜相多晶态逐渐转变为非晶态结构，而随着基片温度的增加，溥膜将由非晶态逐渐转变为单斜相多晶态。同时发现随着氧压升高晶粒尺寸减小，而随着沉积温度增加，晶粒尺寸增大。氧压增加时工艺对表面粗糙度有一定程度的改善，而沉积温度升高，工艺对表面粗糙度的改善不明显。晶粒尺寸大小变化与表面粗糙度变化存在对应关系。激光损伤测量表明

Annealing effects on electron-beam evaporated Al2O3 films

The effects of post-deposited annealing on structure and optical properties of electron-beam evaporated Al2O3 single layers were investigated. The films were annealed in air for 1.5 h at different temperatures from 250 to 400 degrees C. The optical constants and cut-off wavelength were deduced. Microstructure of the samples was characterized by X-ray diffraction (XRD). Profile and surface roughness measurement instrument was used to determine the rms surface roughness. It was found that the cut-off wavelength shifted to short wavelength as the annealing temperature increased and the total optical loss decreased. The film structure remained amorphous even after annealing at 400 degrees C temperature and the samples annealed at higher temperature had the higher rms surface roughness. The decreasing total optical loss with annealing temperature was attributed to the reduction of absorption owing to oxidation of the film by annealing. Guidance to reduce the optical loss of excimer laser mirrors was given. (c) 2004 Elsevier B.V. All rights reserved.

铬过渡层对银膜光学性质及附着力的影响

研究了在玻璃基底上采用不同厚度的铬膜作过渡层，对银膜的光学性质及其附着力的影响。光谱测量结果表明，随着铬膜层厚度的增加，银膜的反射率先增大后减小。与直接镀在玻璃基底上的银膜的反射率相比，铬膜层厚度为8～14nm时，银膜的反射率较低；铬膜层厚度为17～21nm时，银膜的反射率得到提高，其中铬膜厚度为17nm时，银膜的反射率最高；继续增加铬膜层的厚度，银膜的反射率又降低，说明采用一定厚度的铬膜作过渡层可以提高银膜的反射率。X射线衍射（XRD）结构分析表明，一定厚度的铬膜改善了银膜的结晶程度，使薄膜的晶粒度增大

退火对ZrO2薄膜微结构及激光损伤阈值的影响

利用电子束蒸发方法在Yb:YAG晶体和熔融石英衬底上沉积单层ZrO2薄膜,分别在673 K和1 073 K的温度下经过12 h退火以后,通过X射线衍射(XRD)分析了薄膜晶相,计算了薄膜的晶粒尺寸;利用表面热透镜技术获得了薄膜的吸收;测量了退火后薄膜的激光损伤阈值.实验结果表明:两种衬底上的薄膜结构受到退火温度和衬底表面结构的影响,高温退火有利于单斜相的形成,含单斜相的ZrO2薄膜具有较高的激光损伤阈值,而由于衬底的吸收,Yb:YAG晶体上薄膜的损伤阈值远小于石英衬底上薄膜的损伤阈值.

退火对电子束热蒸发Al2O3薄膜性能影响的实验研究

用电子束热蒸发方法镀制了Al2O3材料的单层膜，对它们在空气中进行了250～400℃的高温退火。对样品的透射率光谱曲线进行了测量，计算了样品的消光系数、折射率和截止波长。通过X射线衍射仪(XRD)测量分析了薄膜的微观结构，采用表面轮廓仪测量了样品的表面均方根粗糙度。结果发现随着退火温度的提高光学损耗下降，薄膜结构在退火温度为400℃时仍然为无定形态，样品的表面粗糙度随退火温度的升高而增加。引起光学损耗下降起主导作用的是吸收而不是散射，吸收损耗的下降主要是由于退火使材料吸收空气中的氧而进一步氧化，从而使薄膜

沉积温度对HfO2薄膜残余应力的影响

用电子柬蒸发方法制备了HfO2薄膜，根据镀膜前后基片曲率半径的变化，用Stoney公式计算了薄膜应力。讨论了沉积温度对薄膜残余应力的影响。结果发现，HfO2薄膜的残余应力均为张应力，应力值随沉积温度的升高先增大后减小，在280℃左右出现极大值。对样品进行了XRD测试，从微观结构上对实验结果进行了分析，发现微结构演变引起的内应力变化是引起薄膜残余应力改变的主要因素，HfO2薄膜在所选沉积温度60～350℃内出现了晶态转变，堆积密度随温度升高而增大。

高真空室中的水蒸气对HfO2薄膜性能的影响

本文研究了在镀膜过程中真空室内水蒸气的含量对HfO2薄膜物理性能的影响。用电子束蒸发和光电极值监控的方法在BK7基底上制备HfO2薄膜。利用残余气体分析仪在线监测了真空室内的残余气氛组成。分别用Lambda 900光谱仪、X射线衍射方法、表面热透镜技术和1064nm的激光器测试了薄膜的光学性能、微结构、吸收和激光损伤阈值。实验发现，附加冷阱装置有助于我们有效控制镀膜过程中的水汽含量，且在水蒸气含量较少的真空室内镀制的薄膜具有较高的折射率，较小的晶粒尺寸，较低的弱吸收值和较高的损伤阈值。