化学处理对熔石英表面抗激光损伤阈值的影响

分析了HF酸腐蚀时间对熔石英抗激光损伤阈值的影响.用浓度为4%的HF酸腐蚀15min后,测得熔石英抗激光损伤阈值提高了53.1%,并对其机理作了分析.激光损伤实验使用波长为355nm,脉宽为10ns,频率为3Hz的Nd:YAG调Q激光器测试系统.当泵浦激光辐照熔石英样品表面时,后表面比前表面更容易发生激光诱导损伤,HF酸腐蚀的程度对前后表面抗激光损伤阈值比基本没有影响.对实验样品在HF酸腐蚀前后表面粗糙度的测量结果表明,HF酸腐蚀时间较短时实验样品表面粗糙度基本无变化,如果选用的样品存在较多的表面及亚表面缺陷,当HF酸腐蚀去除掉重沉积层后,表面粗糙度将急剧上升.     

熔石英元件抛光加工亚表面缺陷的检测

亚表面缺陷的准确检测是进行亚表面损伤研究的前提和基础,对保证光学元件加工质量至关重要.基于HF酸化学蚀刻法对熔石英元件抛光加工产生的亚表面水解层、缺陷层深度和亚表面损伤形貌进行了定量检测,并利用X射线荧光光谱法研究了熔石英抛光试件杂质元素的种类和元素含量沿深度分布规律,提出了熔石英元件抛光加工亚表面损伤深度的判定方法.研究表明:由于水解层和亚表面缺陷层的存在,熔石英抛光试件的蚀刻速率随着时间的增加呈现递减的趋势,且在蚀刻的初始阶段蚀刻速率下降尤为明显;当蚀刻深度超过某一特定值后,全部或部分覆盖在水解层以下的缺陷层将会被完全蚀刻去除,蚀刻速率基本保持不变;另外,熔石英抛光试件存在多种形式的表面及亚表面缺陷,在不同蚀刻深度,亚表面损伤形貌、划痕的宽度和深度也存在一定的差异.     

熔石英在3ω激光下输入输出面的阈值分析

在紫外激光条件下对熔石英样品输入输出面进行了损伤阈值测试,测试结果表明熔石英样品输入面损伤阈值是输出面的1.25倍.其损伤形貌基本表现为小麻孔聚集和烧蚀疤痕,表明其损伤由激光驻波场和烧蚀共同引起,并用激光压力模型对其损伤机理进行了分析.     

硅片载体表面形貌对蛋白质吸附的影响

采用固定金属离子亲和技术在不同表面形貌的硅基片上交联金属离子螯合物,蛋白质分子通过其末端的组氨酸标记(His-tag)与金属离子螯合,定向结合于硅基片表面构成蛋白质芯片,考察了不同表面形貌的硅基片对蛋白质的吸附行为.结果表明:硅基片的表面形貌对蛋白质的吸附行为有很大影响.硅基片经碱蚀刻获得的绒面氧化后因其较大的比表面积、特殊的空间结构及较小的固液接触角θ,对蛋白质具有较强的吸附能力,螯合的蛋白质种类多、丰度大.     

基于SPM的花生酸LB膜的拉膜工艺及结构表征的研究

通过扫描探针显微镜（SPM）直接观察沉积在基片表面的花生酸LB（Langmuir-Blodgett）薄膜不同范围尺度下的微观结构.研究在经过表面两亲性（亲水性或疏水性）处理的基片上,在相同的制膜条件下,改变其拉膜沉积方式,对花生酸LB膜样品的表面结构、薄膜均匀性和缺陷等的影响.结果显示,花生酸LB膜在不同拉膜沉积方式下,薄膜表面将形成不同的分子自组装形态;改变基片表面的亲水性强弱也直接影响LB膜的表面形貌的均匀性,可能通过选择恰当表面处理和沉积方式来获得平整度更高,缺陷更少的LB膜.     

制备条件对ZrO2光学薄膜特性的影响

以锆酸丁酯为前驱体,采用溶胶-凝胶工艺,制备了性能稳定的ZrO2溶胶,通过在其中添加有机粘合剂PVP和旋涂镀膜法分别制得了ZrO2薄膜和ZrO2-PVP复合薄膜.用X射线衍射仪(XRD)、椭圆偏振光谱仪、红外分光光度计(FTIR)、原子力显微镜(AFM)等方法研究了不同热处理温度下的ZrO2和ZrO2-PVP复合薄膜的特性,并用输出波长1.06μm、脉宽10ns的电光调Q激光系统产生的强激光进行辐照实验,测试其激光损伤阈值,观察其损伤形貌.实验发现,经过粘合剂添加能很好地提高薄膜的激光损伤阈值,300℃是比较适合的热处理温度.热处理300℃的ZrO2-PVP复合薄膜的激光损伤阈值可达到52 J/cm2.     

熔石英光学元件纳米划痕亚表面损伤特性

为了实现熔石英光学元件激光损伤阈值的提升,本文分析了划痕对熔石英激光损伤的影响,利用纳米压痕实验区分塑脆划痕,通过时域有限差分(FDTD)算法仿真给出不同深度、不同宽深比的划痕对光场调制的影响结果,最后选取典型划痕进行R-on-1激光阈值测试实验.结果表明,深度在53 nm以下的塑性划痕对激光损伤无影响,处于塑脆转变阶段的划痕有一定几率诱导损伤,脆性划痕处损伤阈值远远低于基底阈值,仅为基底阈值的43.1%,是降低光学元件激光损伤阈值的重要因素.实验数据与理论仿真具有一致性.     

激光功率对不锈钢表面清洗效果影响的研究

利用激光清洗技术对不锈钢表面进行清洗试验,研究不同激光功率(300W、400W、500W)对清洗效果的影响。通过SEM和EDS分析不锈钢表面清洗前后的表面形貌及成分分布;利用白光干涉仪检测不锈钢表面粗糙度及清洗厚度。结果表明,随着激光功率的增加,不锈钢表面氧化物逐渐分解剥落,清洗厚度不断加深,在500W时达到50pm,并且造成基体部分损伤;粗糙度值先降低后增加,在400 W时达到最低值0.38 pm。激光清洗的清洗阈值近似为3.96×103 W/cm2,基体损伤阈值在5.52×103 W/cm2左右,不锈钢表面氧化层在400W时达到最佳激光清洗效果。     

氨处理对溶胶凝胶增透膜激光损伤阈值的影响

采用溶胶凝胶方法在K9 玻璃基片上镀制了SiO2 增透膜,并对其中一些样品进行了氨处理.分别采用原子力显微镜、红外光谱仪、椭偏仪、透射式光热透镜测试了氨处理前后薄膜的微观表面形貌、化学结构、折射率和弱吸收.实验结果表明:经氨处理后薄膜的孔隙率从0.73 降低到0.63 ,其弱吸收从67.88 ×10 -6 增加到74.58 ×10 -6 ,薄膜的激光损伤阈值从处理前的18.0 J/cm 2 降低到16.9 J/cm 2 .考虑到氨处理能提高SiO2 增透膜的机械性能,实际应用中应根据需要折中处理.     

K9和熔石英玻璃纳秒基频激光损伤特性的实验对比研究

利用光学元件基频激光损伤测试平台,通过实验测试相同条件下K9和熔石英两类常用光学元件的初始损伤阈值、损伤增长阈值和损伤增长规律,对比研究了两类光学元件的基频激光损伤特性.结果表明,K9和熔石英光学元件的初始损伤阈值基本相同,损伤面积增长都遵循指数性增长规律,损伤深度成线性增长.但两者损伤增长特性仍有很大的差别,与熔石英相比,K9激光损伤增长阈值较低,并且相同通量下的激光损伤增长更为迅速,通过两类光学材料抗压性能的巨大差异很好地解释了这一现象.该研究结果对国内高功率激光装置的透射光学材料工程应用有非常重要的参考价值.     

Dry Etching with Nanoparticles: Formation of High Aspect‐Ratio Pores and Channels Using Magnetic Gold Nanoclusters

Methods for generating nanopores in substrates typically involve one or more wet‐etching steps. Here a fundamentally different approach to produce nanopores in sheet substrates under dry, ambient conditions, using nanosecond‐pulsed laser irradiation and magnetic gold nanoclusters (MGNCs) as the etching agents is described. Thermoplastic films (50–75 µm thickness) are coated with MGNCs then exposed to laser pulses with a coaxial magnetic field gradient, resulting in high‐aspect ratio channels with tapered cross sections as characterized by confocal fluorescence tomography. The dry‐etching process is applicable to a wide variety of substrates ranging from fluoropolymers to borosilicate glass, with etch rates in excess of 1 µm s^–1. Finite‐element modeling suggests that the absorption of laser pulses by MGNCs can produce temperature spikes of nearly 1000 °C, which is sufficient for generating photoacoustic responses that can drive particles into the medium, guided by magnetomotive force.     

激光化学诱导液相腐蚀新方法

提出了一种激光诱导液相腐蚀新方法——抗蚀膜掩蔽法。抗蚀膜掩蔽法是指在激光腐蚀中,用抗蚀膜来实现对激光腐蚀区域的控制。理论分析和实验结果都表明,抗蚀膜掩蔽法可以有效地控制激光化学腐蚀的图像形状;因不需要对激光光束进行聚焦,光传播垂直于基片表面,制作出的腐蚀孔侧壁可以具有很高的垂直度;利用激光光束中心区域能量分布近似均匀的特点,使小面积腐蚀区域的腐蚀速率近似相等,腐蚀面内各点没有明显的高度差。因为以上优点,抗蚀膜掩蔽法能克服现有激光腐蚀方法的诸多弊端,简化激光腐蚀工艺,在特殊结构光电器件和光电集成中具有广泛的应用前景。     

Fabrication and characterization of microstructures with optical quality surfaces in fused silica glass using femtosecond laser pulses and chemical etching

We present a study of the sidewall surface quality inside microchannels fabricated in fused silica glass by femtosecond laser pulses and chemical etching. Multiple combinations of laser exposure and etching solution parameters were examined. Results of scanning electron microscopy, atomic force microscopy, and optical reflection analyses of the surfaces are presented. The results obtained demonstrate the feasibility of optical quality surface fabrication, which in turn demonstrates the feasibility of fabricating complex integrated devices containing microfluidic channels and optical waveguides in the glass substrates.     

Influence of cleaning process on the laser-induced damage threshold of substrates

The cleaning process of optical substrates plays an important role during the manufacture of high-power laser coatings. Two kinds of substrates, fused silica and BK7 glass, and two cleaning processes, called process 1 and process 2 having different surfactant solutions and different ultrasonic cleaning parameters, are adopted to compare the influence of the ultrasonic cleaning technique on the substrates. The evaluation standards of the cleaning results include contaminant-removal efficiency, weak absorption, and laser-induced damage threshold of the substrates. For both fused silica and BK7, process 2 is more efficient than process 1. Because acid and alkaline solutions can increase the roughness of BK7, process 2 is unsuitable for BK7 glass cleaning. The parameters of the cleaning protocol should be changed depending on the material of the optical components and the type of contamination.     

Laser damage resistance of hafnia thin films deposited by electron beam deposition, reactive low voltage ion plating, and dual ion beam sputtering

A comparative study is made of the laser damage resistance of hafnia coatings deposited on fused silica substrates with different technologies: electron beam deposition (from Hf or HfO(2) starting material), reactive low voltage ion plating, and dual ion beam sputtering. The laser damage thresholds of these coatings are determined at 1064 and 355 nm using a nanosecond pulsed YAG laser and a one-on-one test procedure. The results are associated with a complete characterization of the samples: refractive index n measured by spectrophotometry, extinction coefficient k measured by photothermal deflection, and roughness measured by atomic force microscopy.     

Influence of WC-Co substrate pretreatment on diamond film deposition by laser-assisted combustion synthesis

The quality of diamond films deposited on cemented tungsten carbide substrates (WC-Co) is limited by the presence of the cobalt binder. The cobalt in the WC-Co substrates enhances the formation of nondiamond carbon on the substrate surface, resulting in a poor film adhesion and a low diamond quality. In this study, we investigated pretreatments of WC-Co substrates in three different approaches, namely, chemical etching, laser etching, and laser etching followed by acid treatment. The laser produces a periodic surface pattern, thus increasing the roughness and releasing the stress at the interfaces between the substrate and the grown diamond film. Effects of these pretreatments have been analyzed in terms of microstructure and cobalt content. Raman spectroscopy was conducted to characterize both the diamond quality and compressive residual stress in the films.     

Deposition of SiO2 films with high laser damage thresholds by ion-assisted electron-beam evaporation

SiO(2) thin films ( approximately 100 nm thick) with transmittivity and a laser damage threshold nearly equal to those of bulk material are deposited on silica substrates by the technique of ion-assisted electron-beam evaporation. The influence of film packing density on the laser damage threshold is investigated by the technique of photoacoustic probe beam deflection. It is shown that films with lower packing density may have a higher laser damage threshold and as a consequence better heat dissipation.     

集成工艺中湿法刻蚀对锆钛酸铅性能的影响(英文)

通过将溶胶凝胶法制备的锆钛酸铅(PZT)在非晶态和多晶态进行刻蚀,对比未经刻蚀的PZT性能,研究了集成工艺中湿法刻蚀造成极化和耐久性能退化的机理.PZT的结晶图谱和表面形貌分析发现,湿法刻蚀中产生的非铁电成分由于具有较小的介电常数,降低了铁电材料上分担的有效测试电压,导致刻蚀后PZT极化能力的降低.未刻蚀的PZT翻转1011次后极化值损失约3%,而刻蚀后极化值减小量大于5%.随着尺寸的减小,耐久特性的降低更为明显,100μm×100μm的PZT极化值减小量约为500μm×500μm样品的3倍.高温过程中由于湿法刻蚀而产生的缺陷和空隙在PZT内部重新分布,外加电压下有更多的电子被缺陷和空隙束缚而产生内建电场并钉扎铁电畴,不同器件尺寸的PZT内部缺陷和空隙浓度的变化不同,导致耐久特性随PZT器件尺寸而不同.利用压电特性参数与极化强度的关系,可以解释湿法刻蚀对压电特性造成损伤的原因.     

Laser etching and dry processing

Controlled, anisotropic etching of different materials commonly used in microelectronics is an important processing step in microfabrications. During recent years it has been demonstrated that lasers can be used for initiating and enhancing the etching process in many gas-solid (dry processing) and liquid-solid (wet processing) systems. The laser-induced reaction could be either photochemical or thermochemical. Using laser etching technique a variety of materials such as Al, Ta, Ni/Fe, GaAs, InP, Si, SiO₂ mylar, different polymers and superconducting materials have been processed. In this paper we briefly review these laser etching experiments.