近红外宽截止窄带滤光膜的研制

在空间光通信系统中,为满足光学系统对滤光膜的特殊要求,研制出了一种近红外宽截止窄带滤光膜,实现了降低深背景范围内杂散光干扰的要求.通过对薄膜材料特性的研究、膜系设计曲线的不断优化,得到了相对易于制备的窄带滤光膜结构;采用电子束加热蒸发及离子辅助沉积技术制备薄膜,采用光控加晶控同时监控的方法监控膜层厚度,通过不断优化工艺参量,提高中心波长处的透过率,最终成功得到了光谱性能较好的滤光膜.经光谱测试表明:所镀膜层在800~1 530nm、1 600~1 800nm波段平均透过率低于0.3%,1 565nm单点透过率高于92%,通带半带宽为18nm,满足光学系统的使用要求.     

1064nm激光与远红外共窗口成像系统波长分离膜的研制

根据激光与远红外共窗口成像系统的技术要求,研制了一种波长分离膜,实现通过共窗口的激光与远红外光分离成像,即1 064nm高反射、8~14μm高透射.分析薄膜的微观结构,研究了薄膜材料吸潮前后的折射率变化,结合光学薄膜理论,优化膜系结构.在薄膜应力的基础上,优化膜层厚度,提高薄膜牢固性.研制的分离膜,1064nm反射率为99.71%,8~12μm平均透过率为97.1%,12~14μm平均透过率为90.1%,满足户外环境中长期使用的要求.     

1555nm宽带通滤光膜的设计和优化

针对对空间通信的特殊需求,设计并制备了1 555 nm波段的高透过率、宽带通滤光膜,该滤光膜在高温高湿环境下能够稳定工作。根据薄膜设计理论,选取折射率差大的TiO2和SiO2作为镀膜材料,采用规整膜系进行膜系设计。借助Optilayer软件,采用针形优化和双面镀膜方法,得到优化的非规整膜系。采用直接与间接监控相结合的手段监控薄膜生长,并探讨了薄膜的生长条件。在电子束蒸发离子辅助沉积条件下,制备出中心波长处透过率达到97%,带宽为50 nm的滤光膜。在100℃高温和-30℃低温各保持3 h的条件下,波长漂移仅0.2 nm,具有高的稳定性和可靠性,满足空间通信的使用要求。     

高损伤阈值三倍频分离膜

 设计了Nd：YAG激光用三倍频分离膜,膜层材料为SiO₂和HfO₂。经过优化,膜系在355 nm处的反射率在99%以上,在532 nm和1 064 nm处透射率也在99%以上。采用电子束蒸发技术,在熔融石英基底上制备了样品,经测量,制备的分离膜光学性能与设计值接近。分离膜在355 nm激光辐照下的损伤阈值为5.1 J/cm²,并用微分干涉显微镜表征了薄膜损伤形貌。     

双波段截止分色滤光片研究

为实现45°入射情况下K9基底上双波段截止分色的特性(截止带波长0.5~0.68μm、0.73~0.79μm,通带波长0.83~0.87μm),采用F-P型的带通滤光片膜系结构为初始结构,与常规设计理念相比有效减少了膜层的数量,薄膜的高折材料采用Ti O2,低折材料采用Si O2,以实现双波段截止的目的。膜层的设计层数为23层,总厚度为2.278μm,借助电子束蒸发物理气相沉积法实现了镀制,利用分光光度计对镀制样品的透过率进行评估。测试结果显示,截止区(0.5~0.68μm和0.73~0.79μm)平均截止深度分别达到了12.57%和20.39%,通带0.83~0.87μm波段内的平均透过率达到了91.35%,样品测试曲线与设计相比,"蓝移"将近10 nm。薄膜样品基本实现了设计目标,具有双波段截止、高通带透过率的特性。在环境测试中:薄膜表现出显著的稳定性,膜层间匹配度适宜。该双波段截止分色滤光片能够应用在一些极端的情况下。     

多层增透薄膜透射特性仿真分析

基于多层薄膜的组成特性,建立了可见光波段以氧化铪和二氧化硅为高、低折射率材料的多层增透膜模型,计算机仿真结果表明:当膜层为单层膜时,其中心透射率为17.31%,通带宽度为102nm;而当膜层增至十一层和二十一层时,其中心透射率分别达到了99.30%和99.99%,但其通带宽度却分别下降至57.1nm和50.2nm.研究表明:随着膜层的不断增加,膜系的透射率也在逐渐增加,且透射率增加的趋势随着膜层数增加而变缓,峰值透射波长缓慢减小,通带半宽度也逐渐变小.     

脉宽压缩光栅用的多层膜设计和性能分析

应用于啁啾脉冲放大技术中的脉宽压缩光栅是基于多层膜作为基底,利用全息干涉技术和离子束技术刻蚀而成。脉宽压缩光栅的衍射效率和抗激光损伤阈值一方面依赖于光栅结构的设计,另一方面很大程度上取决于作为基底的多层膜的设计。给出了以413.1nm作为写入波长,1053nm作为使用波长的多层介质光栅膜的设计,样品在ZZS-800F型真空镀膜机上采用电子束蒸发方式沉积而成,并给出了膜系结构对光学性能影响因素的详细分析,结果表明膜系H3L(H2L)9H0.5L2.03H满足光栅膜的指标。给出了样品光学特性测试,其使用波长处的透射率<0.5%,写入波长处的透射率>90%,测试表明样品满足设计要求且实验结果和理论设计符合得很好。     

COIL用薄膜90°位相延迟高反射镜的研制

随着氧碘化学激光器（COIL）输出功率的不断提高，传统的膜系设计已不能满足要求。在倍频膜系的设计基础上，优化设计出了激光45°入射时对1 315 nm和632.8 nm双波长高反（HR）并在1 315 nm处具有90°位相延迟的高反射镜，其基底材料为融石英，高折射率材料为ZrO2, 低折射率材料为SiO2。然后，采用电子束蒸发手段制备了口径为200 mm的高反射位相延迟镜。最后对该延迟镜的性能进行了测试，结果表明:对632.8 nm波长的反射率大于等于95.0%，对1 315 nm波长的反射率大于等于99.8%,位相延迟在90.235°～95.586°范围内。     

矩形波宽带通滤光膜研究

对矩形波宽带通滤光片进行了深入研究,提出了一种设计、制备矩形波宽带通滤光片的方法。使用该方法设计并制备了400 nm～1 100 nm波段,中心波长λ₀=515 nm,透射带λ=λ₀±25 nm,透射带平均透射率■≥92%,截止带λ=400 nm～475 nm、λ=555 nm～1 100 nm,截止带透射率小于0.1%的矩形波宽带通OD3-A滤光片。对样片光谱进行了测试,结果满足需求。该方法设计、制备矩形波宽带通滤光片克服了F-P型窄带滤光膜监控精度要求高、通带宽带窄、成本高以及传统长、短波截止膜组合方式膜层总厚度过大、通带透过率低、波形矩形度差的缺点。     

人眼安全激光测距与红外成像滤光膜的研制

从人眼安全的角度,设计并制备了对1 064 nm激光抑制并可用于1 550 nm激光测距以及3 m～5 m波段红外成像的滤光膜。选用ZnS、YbF3作为膜料组合、多光谱ZnS作为基底,利用薄膜设计软件对薄膜进行了优化设计。膜系设计通过合理的厚度控制和膜层安排,来增强薄膜的机械强度。滤光膜的制备采用了电子束沉积技术,通过离子辅助沉积和真空退火处理技术,进一步提高滤光膜的牢固性。光谱测试表明:在1 064 nm处的透射率仅为0.5%,1 550 nm处的透过率为99.3%,3 m～5 m波段的平均透过率大于96%,经分析YbF3的折射率在薄膜沉积过程中有所提高,但是对光谱曲线影响不大;可靠性测试表明:滤光膜能够耐受恶劣的环境考验,满足使用要求。     

Efficient antireflective downconversion Er3+ doped ZnO/Si thin film

This study is an investigation of the potential of Er doped ZnO thin films for downconversion photons and an antireflective layer when placed in front of the silicon solar cells. We optimized the properties of the film with appropriate deposition conditions on Si (111) substrate by aerosol assisted chemical vapor deposition (AACVD) process. An enhancement of both crystallinity and optical response was achieved in the case of film doped with 2.504 at.% Er³⁺. A low reflectance and high refractive index of the film were obtained at around 632 nm. Downconversion process was also reached for this film under visible excitation to near-infrared (NIR) 980 nm photons useful for Si solar cell.     

Directly diode-pumped Yb:KY(WO(4))(2) regenerative amplifiers

Two Yb(3+) -doped KY(WO(4))(2) regenerative amplifiers, one end pumped by two 1.6-W single-stripe diodes at 940 nm and the other side pumped by one 20-W diode bar at 980 nm, are demonstrated. When the regenerative amplifiers are injected, 40-muJ , 400-fs and 65-muJ , 460-fs pulses at a 1-kHz repetition rate are obtained following compression from the end- and side-pumped amplifiers, respectively.     

X射线W/B4C宽带多层膜的优化设计和制备

介绍了X射线宽带多层膜材料W和B4C的选定方法,依据伯宁(BERNING)公式确定出了在0.154 nm处X射线宽带多层膜的最佳膜对数。引入适当的评价函数,利用具有全局寻优特性且效率较高的遗传算法,在波长0.154 nm处优化设计出了掠入射角(θ)0.5°~0.9°范围内反射率值达到40%的宽角度宽带多层膜。宽带多层膜反射镜采用磁控溅射方法制备,并用X射线衍射仪对样品进行了检测,结果表明在掠入射角(2θ)1.0°~1.8°之间的相对反射率光谱曲线比较平坦。     

Numerical Analysis of Multilayer Waveguides Using Effective Refractive Index Method

With the help of the effective refractive index method we have numerically analyzed a multilayer planar waveguide structure and calculated the propagation constants, confinement factors, and transverse electric (TE) modes. A five-layer waveguide model has been provided to analyze the electro-magne tic wave propagation process. The analysis method has been applied to the 980 nm laser with active layer of GaInAs/GaInAsP strained quantum wells, GaInAsP confinement layers and GaInP cap layers. By changing the thickness of confinement layers, we obtained confinement factor as high as 95% with higher TE modes TE1 and TE2. The results are in good agreement with the experiment by A. Al-Muhanna et al. and give the new idea to enhance output power of semiconductor lasers. The analysis method can also be extended to any other slab multilayer waveguide structures, and the results are useful to the fabrication of optic-electronic devices.     

ZnO/Ag/ZnO multilayer films for the application of a very low resistance transparent electrode

Transparent conductive ZnO/Ag/ZnO multilayer electrodes having much lower electrical resistance than the widely used transparent electrodes were prepared by simultaneous RF magnetron sputtering of ZnO and DC magnetron sputtering of Ag. An Ag film with different thickness was used as intermediate metallic layers. The optimum thickness of Ag thin films was determined to be 6 nm for high optical transmittance and good electrical conductivity. With about 20-25 nm thick ZnO films, the multilayer showed high optical transmittance in the visible range of the spectrum and had color neutrality. The electrical and optical properties of the multilayers were changed mainly by Ag film properties. A high quality transparent electrode, having sheet resistance as low as 3 ohm/sq and high transmittance of 90% at 580 nm, was obtained and could be reproduced by controlling the preparation parameter properly. The above property is suitable as transparent electrode for dye sensitized solar cells (DSSC).     

30.4 nm波长SiC/Mg多层膜反射镜

波长30.4 nm的He-II谱线是极紫外天文观测中最重要的谱线之一,空间极紫外太阳观测光学系统需要采用多层膜作为反射元件。为此研究了SiC/Mg、B4C/Mg、C/Mg、C/Al、Mo/Si、B4C/Si、SiC/Si、C/Si、Sc/Si等材料组合的多层膜在该波长处的反射性能。基于反射率最大与多层膜带宽最小的设计优化原则,选取了SiC/Mg作为膜系材料。采用直流磁控溅射技术制备了SiC/Mg多层膜,用X射线衍射仪测量了多层膜的周期厚度,用国家同步辐射计量站的反射率计测量了多层膜的反射率,在入射角12°时,实测30.4 nm处的反射率为38.0%。     

MOCVD原位红外测温方法的比较研究

MOCVD原位红外测温方法主要有单色辐射测温法与双波长比色测温法。利用薄膜等厚干涉模型与Kirchhoff定律计算了Si (111)衬底生长10 m GaN外延片的940 nm、1 550 nm光谱发射率,以Thomas Swan CSS MOCVD为例,比较了500 ℃至1 300 ℃范围内,940 nm单色辐射测温法、1 550 nm单色辐射测温法、940 nm与1 550 nm双波长比色测温法的相对误差和相对灵敏度,以及单色辐射测温法与双波长比色测温法的校准修正,并利用940 nm与1 550 nm双波长比色测温法在线监测了Si (111)衬底生长InGaN/GaN MQW 结构LED外延片过程中的温度。研究表明:940 nm与1 550 nm双波长比色测温法在相对误差及有效探测孔径修正校准上优于940 nm单色辐射测温法和1 550 nm单色辐射测温法,该结论可为MOCVD原位红外测温设备开发提供参考。     

Stress, microstructure and mechanical properties of graded multilayer tetrahedral amorphous carbon films

Tetrahedral amorphous carbon (ta-C) films deposited using a filtered cathodic vacuum arc (FCVA) system, have high intrinsic stress which limits their application as protective coatings. To reduce the film stress and to improve the adhesion, a multilayer structure is deposited at a gradient substrate negative bias from 1500 V to 80 V. This paper investigates the stress, microstructure and nano-mechanical properties of graded multilayer ta-C film on Si substrates. Compared with that of single-layer films deposited at optimised bias, the graded multilayer film has low stress without a decline in hardness and Young’s modulus. Microstructural evaluation of the multilayer film using visible Raman spectra shows that the average content of the sp³ bonds of the multilayer film remain at a high level. Nanoscratch testing illustrates favorable scratch resistance and good adhesion of the multilayer film. Scanning electron microscope (SEM) observation confirms the collapse of the film surface along the scratching trace. Finally, deposition on single crystal germanium substrates of a durable coating ∼ 1100 nm thick, and composed of three graded multilayer films is demonstrated. PACS 81.05.Uw; 81.15.Jj; 68.65.Ac; 68.55.Nq; 68.60.Bs     

MOCVD多功能在线监测探头的设计与实现

根据MOCVD在线监测设备的发展需要,设计了一种多功能在线监测探头,能够同时实现带反射率修正的三种红外辐射测温以及两个波长的反射率曲线监测,即:940nm/1 550nm双波长比色测温、940nm单色辐射测温、1 550nm单色辐射测温、940nm反射率曲线以及1 550nm反射率曲线监测.对探头的比色测温性能进行测试分析,并利用该探头对Si(111)衬底在我国自主研发的MOCVD系统中生长InGaN/GaN MQW结构蓝光LED外延片进行在线监测.结果分析表明:比色测温900℃~1 100℃范围内精度高于1℃;在700℃~1 100℃范围内重复性误差均在0.7℃内;距离容差性为2mm;三种红外测温最低量程均为435℃;并能有效避免探测孔有效面积变化的影响;由940nm反射率曲线得:n-GaN层的膜厚监测相对误差为3.6%.该设计能够同时实现MOCVD在线测温及膜厚测量,可为MOCVD在线监测设备开发提供参考.     

纳米厚度贫铀/Au多层膜的制备及特性研究

理论和实验研究表明,纳米厚度周期调制的贫铀(DU)/Au多层膜材料具有高效的激光X射线转换效率. 采用交替磁控溅射制备纳米厚度的DU/Au平面多层周期结构,通过白光干涉仪、扫描电子显微镜、 X射线光电子能谱对DU/Au多层膜的几何参数、表面形貌、成分以及界面形貌进行表征.实验结果表明: 8 nm为Au连续成膜的厚度阈值,结合理论计算最优化原子配比,选取DU层厚度为30 nm、 Au层厚度为8 nm的调制周期结构;实测周期厚度为37 nm;扫描电子显微镜照片显示DU/Au分层明显; X射线光电子能谱深度刻蚀分析表明DU/Au界面处存在扩散, DU, Au, O三者原子比为73:26:1; 由于团簇效应, Au原子4f电子结合能向高能端移动,没有观察到DU相应的电子结合能移动现象.