具有亚表面损伤层基底表面的激光减反膜设计

光学材料的亚表面损伤层（SSD）是激光光学领域内的研究热点之一。亚表面损伤层的存在将导致其表面薄膜特性发生变化,尤其是在高精度低损耗激光薄膜的设计与制造中亚表面损伤层必须给予考虑。文中研究了亚表面损伤层的物理特性,并借助于椭圆偏振仪测量基底表面的椭偏光谱,反演计算出SSD 的物理厚度和折射率梯度。通过计算得到了亚表面的深度和梯度对激光减反膜反射率光谱的影响,证明了亚表面深度对反射率的影响具有周期效应。在考虑亚表面损伤层的深度和梯度存在的基础上,对激光减反膜的设计进行了理论修正,数值实验结果证明通过膜系的修正可以实现633 nm 处的零反射。     

激光辐照下光学薄膜元件温升的有限元分析

实验测量了波长1 064 nm,10 kHz高重复频率激光辐照下镀制Ta2O5/SiO2多层膜的 K9、石英玻璃、白宝石高反膜元件温升变化.有限元分析的结果与实验结果相一致.用ANSYS程序计算了不同基板、空气对流系数及基板尺寸对激光辐照中心点温度的影响.结果表明:白宝石基片的薄膜元件激光辐照点的温度最低,其次是石英,K9玻璃基片的薄膜元件激光辐照点温度最高.空气对流系数在大光斑或长时间辐照时对激光辐照点温度影响较大,在小光斑或短时间辐照时对激光辐照点温度影响甚微,可忽略不计.基板越厚,基板直径越大,激光辐照中心点温度越低,基板直径比厚度更能影响激光辐照中心点温度变化.     

多孔性二氧化硅减反膜胶体规律性研究

溶胶凝胶法制备减反膜在高功率激光装置中有着重要运用,通过控制水与正硅酸乙酯(TEOS)不同物质的量之比制备不同粒径大小的二氧化硅悬胶体及二氧化硅减反膜,可以研究悬胶体粒径大小对溶液及膜层的激光破坏阈值、光学减反效率稳定性影响。结果表明制备获得的多孔性SiO2减反膜透射率均高于99.5%,激光破坏阈值均大于62J/cm2(1064nm,15ns),其中粒径小的SiO2减反膜透射率达到99.75%,激光破坏阈值高达77.42J/cm2(1064nm,15ns)。随着水酯物质的量比值增大,悬胶体溶液平均粒径增大,当水酯物质的量比值大于3.5时粒径增大幅度加快;粒径在10nm以下的溶液具有优异的稳定性,溶液颗粒大小、粘度等性能基本保持不变。在不同湿度环境下研究不同粒径膜层的稳定性,所有膜层在高湿度环境中透射率有所下降,其中大粒径膜层下降更明显,化学膜更适合在湿度低的环境下使用。     

高功率激光单层SiO2减反膜的研制

开发出了一种用于制备高功率激光系统中玻璃表面窄带型减反膜的化学制膜法。这种减反膜由含SiO2粒子的悬浮液在室温下涂敷制得,无需进一步的后处理工序。K9玻璃透镜及石英玻璃透镜涂敷这种SiO2减反膜后,其最高透光率均达99%以上。     

有机物沉积质量对溶胶凝胶减反膜性能的影响规律

真空环境中高功率激光装置光学元件表面的有机物污染是限制其负载能力的原因之一。针对装置中常见的有机物污染和三倍频激光溶胶凝胶减反膜，通过精确控制真空环境中污染源的挥发扩散，制备了有机物质量面密度不同的元件表面，定量研究了有机污染物质量面密度对溶胶凝胶减反膜光学性能及损伤特性的影响规律。实验结果表明：样品表面粗糙度、透过率、损伤阈值等的变化量均与有机物质量面密度成正相关。有机污染物沉积量较少时，由于膜层孔隙被填充，膜层的表面粗糙度略有减小；随着沉积量增加，有机物附着影响表面形貌，粗糙度显著增加。溶胶凝胶减反膜在351 nm波长处的光学透过率随着有机物质量面密度的增加而逐渐降低，这与有机物分子改变溶胶凝胶膜孔隙填充比有关。样品表面的激光损伤阈值变化量和损伤面积随着有机物质量面密度的增加而增加，而且不同有机物沉积量的光学表面的损伤形貌存在显著差异。基于实验结果讨论了有机物影响溶胶凝胶减反膜性能的机理，并探讨了高功率激光系统的洁净度控制方法。     

太阳电池减反膜的设计

设计良好的减反膜系,提高太阳电池的光电转换效率是太阳电池研制中的一个重要问题.文章从减反膜理论出发,利用计算机软件模拟分析,获得了单层膜、双层膜系反射率百分比与波长的关系,并给出了具体入射波长(即632.8 nm、800 nm)条件下膜的最佳厚度.采用PC1D软件模拟了覆盖减反膜的单晶硅电池的I-V曲线,证实电池转换效率大大提高.研究结果可应用于太阳电池的设计中.     

遗传算法设计电磁屏蔽减反膜

将电磁屏蔽层ITO薄膜作为一层光学薄膜,与TiO2、SiO2、MgF2一起,设计了宽带电磁屏蔽减反膜。给出了含有单层、双层、三层ITO的电磁屏蔽减反膜的膜系结构,其在可见光范围内剩余反射率均小于0.5%,满足ISO9211标准。该薄膜既具备光学减反效果,同时又具备电磁屏蔽功能,可以用作电磁屏蔽视窗。     

Si光电器件表面减反膜设计的数值分析

本文通过计算、分析在Si光电器件表面由SiO2、Si3N4及AI2O3组成的不同减反膜的反射损耗,得出了最优化的膜层组合。厚度为95nm的SiO2层是最佳的单层减反膜;进一步的优化可采用40nmSi3N4和40nmSiO2或45nm AI2O3和45nm SiO2组成的2层结构;3层或3层以上结构的反射损耗呈振荡性变化,不建议采用。     

用于四结太阳电池的多对TiO2/SiO2减反膜系的研究

随着GaInP/GaInAs/GaInNAs/Ge四结太阳电池的快速发展,设计并镀制可与四结太阳电池更加匹配的光学减反膜系变得尤为重要.实验中通过TFCale软件理论模拟了3对TiO2/SiO2(6层)减反膜系,其中理论模拟膜系与实际镀制膜系反射率曲线重合性良好.实际制备并讨论了离子源功率、薄膜物理厚度等参数对减反膜系反射率的影响.发现得到优异反射率的关键在于对第二层SiO2薄膜物理厚度的控制,尤其是在400～1 000 nm波段内.实验中制备的3对TiO2/SiO2(6层)减反膜系在280～1 400 nm波段内其反射率均小于10％,特别是在影响四结太阳电池限流结的GaInAs/GaInNAs两结波段(670～900 nm/900～1 100 nm)内,其反射率均在5％以下.     

光学薄膜的损耗测试与分析

随着激光基准系统和高精度激光测量系统的发展和应用,推动了超低损耗薄膜技术的发展,进一步控制损耗各分量的大小和分布,需要对光学薄膜总损耗进行测试分析.采用DIBS镀膜工艺在超光滑基底上镀制了高反膜和减反膜,给出了镀膜的工艺方法及工艺参数.通过分析时间衰减法测试总损耗的原理,分别采用时间衰减法和频率扫描法测试了光学薄膜的总损耗,在632.8nm波长点的测试结果为:高反膜层吸收为19.6×10-6,反射率达到99.996 86%;减反膜层总损耗为78×10-6.最后对光学薄膜总损耗的构成和工艺改进进行了探讨.     

用于高功率激光放大器的单层宽谱增透膜

为了获得用于高功率激光放大器的单层宽带增透膜,采用有机聚合物聚乙烯吡咯烷酮掺杂调控二氧化硅胶体生长制备了粒度分布更宽广的稳定胶体体系,通过提拉镀膜工艺,制备了单层增透膜。采用粒度仪和粘度仪监测胶体的性质,用分光光度计测量了膜层透过率,并用X射线能谱分析了膜层结构。结果表明,聚乙烯吡咯烷酮引入胶体中使得胶体粒度分布更宽,所得膜层具有折射率渐变特性,因而膜层具有宽带增透的效果;膜层在550nm~950nm连续波段内透射率不低于99%。单层宽谱增透膜层不需后处理就可投入使用,膜层性能稳定,满足了激光装置片状放大器的运行要求。     

1.3μm high—power superluminescent diode

The result of the evaporation of Sio/SiO2 two layer antireflection coatings monitored by the MODEL IL 400 DEPOSITION CONTROLLER is re-ported.A superluminescent diode with high output power is fabricated by evaporate-ing antireflection coating on the front facet of 1.3цm buried heterostructure laser.     

Fields in extended cavity lasers

The electromagnetic fields for an extended-cavity laser are described precisely and in detail. The extended-cavity laser consists of a semiconductor laser diode with a partially reflecting coating on one facet and an antireflection coating on the other coupled by radiation through a lensed-fiber, single-mode guide to another partially reflecting coating terminating a narrow-wavelength filter. The formulation is based on the Lorentz reciprocity theorem, the fields are described by angular plane-wave spectra, and the equivalent transmission line representation is used to determine the fields reflected and transmitted by partially reflecting and antireflection coatings. The design of antireflection coatings is considered in detail, and a formula which gives the optimum distance from the diode antireflection coating to an inline lensed fiber is derived     

Optimum antireflection coatings for heteroface AlGaAs/GaAs solar cells—Part I: The influence of window layer oxidation

This paper details both the theoretical and experimental results of a modified model for designing MgF₂/ZnS double-layer antireflection coatings for AlGaAs/GaAs heteroface solar cells. The main contribution of the model presented is that it takes into account the possible existence of an oxide layer in the AlGaAs window layer. In a first step the optical behavior of the oxide is modeled and that model is used to recalculate optimal double-layer antireflection coating when a thin AlGaAs oxide layer is present. Significant differences with classical double-layer antireflection coating design are found, such as, the antireflection properties of the oxide layer when formed onto originally thick windows or its equivalent role to that of the ZnS layer (as a high refractive index media) in the coating. Finally, an experimental analysis is carried out to assess empirically the conclusions of the model. These experiments have yielded an excellent agreement with the proposed theory.     

SLA端面增透膜设计的理论分析与计算

文章推导了多层平板波导结构的半导体激光放大器 (SLA)端面反射率的计算方法 ,为优化设计SLA端面增透膜参数提供了工具。对InGaAs/InGaAlAs多量子阱SLA端面增透膜参数进行了优化设计 ,并给出优化结果。     

KTP倍频晶体增透膜的改进

为了改进KTP晶体倍频增透膜的镀膜质量,采用SiO2代替原来使用的MgF2材料作外层膜并重新设计了膜系。实验结果表明,运用上述技术将镀有1064nm和532nm增透膜的KTP倍频晶体应用在高功率Nd:YAG激光器中,当重复频率lkHz、脉宽25ns、基波功率密度高达450MW/cm2时,没有观察到KTP晶体表面激光损伤,膜层表面抗激光损伤和光学性能都得到提高。     

Real-time in situ monitoring of antireflection coatings forsemiconductor laser amplifiers by ellipsometry

Very strict requirements need to be met for producing a high-quality single-layer antireflection coating on a traveling-wave laser amplifier facet. In order to obtain a facet reflectivity of 10^-4 or less, the index of refraction and the layer thickness of single-layer coatings have to be controlled to better than 0.03 and 30 Å, respectively. An innovative approach to highly controlled antireflection layer deposition based on in situ real-time ellipsometry is presented. Index control within ±0.01 and a facet reflectivity on the order of 10^-4 are reproducibly obtained     

Analysis of antireflection coatings on angled facet semiconductor laser amplifiers

An analysis of the modal reflectivity of antireflection coated semiconductor laser amplifiers is presented. The effect of an angle between the facet normal and the amplifier axis is shown to lead to less stringent tolerances on coating index and thickness, and reflectivities of less than 10/sup -4/ can be achieved with a 7 degrees facet angle for TE and TM modes simultaneously.<>     

Performance enhancement of multicrystalline silicon solar cells and modules using double‐layered SiNx:H antireflection coatings

Silicon nitride coating deposited by the plasma‐enhanced chemical vapor deposition method is the most widely used antireflection coating for crystalline silicon solar cells. In this work, we employed double‐layered silicon nitride coating consisting of a top layer with a lower refractive index and a bottom layer (contacting the silicon wafer) with a higher refractive index for multicrystalline silicon solar cells. An optimization procedure was presented for maximizing the photovoltaic performance of the encapsulated solar cells or modules. The dependence of their photovoltaic properties on the thickness of silicon nitride coatings was carefully analyzed. Desirable thicknesses of the individual silicon nitride layers for the double‐layered coatings were calculated. In order to get statistical conclusions, we fabricated a large number of multicrystalline silicon solar cells using the standard production line for both the double‐layered and single‐layered antireflection coating types. On the cell level, the double‐layered silicon nitride antireflection coating resulted in an increase of 0.21%, absolute for the average conversion efficiency, and 1.8 mV and 0.11 mA/cm² for the average open‐circuit voltage and short‐circuit current density, respectively. On the module level, the cell to module power transfer factor was analyzed, and it was demonstrated that the double‐layered silicon nitride antireflection coating provided a consistent enhancement in the photovoltaic performance for multicrystalline silicon solar cell modules than the single‐layered silicon nitride coating. Copyright © 2015 John Wiley & Sons, Ltd.