PECVD技术制备多波段渐变减反膜

介绍了利用傅里叶变化法设计多波段渐变减反膜的原理和方法,研究了采用该方法设计多波段减反膜时Q函数的优选流程,给出了最优Q函数。设计优化得到了在350~5000nm波段范围平均透过率大于90%的多层渐变减反膜系结构,并采用等离子体增强化学气相沉积(PECVD)技术完成了样片的制备。实验结果表明,镀制的样片在350~5000nm波段范围的平均透过率为90.55%,满足光谱特性的要求。     

渐变折射率介质中光线路径的数值计算

从理论上分析了渐变折射率介质中光线传播的规律,建立了光线路径的数值计算方法。     

渐变折射率波导表面折射率的确定

单调变化的渐变折射率波导的表面折射率大于波导基模的有效折射率,因而不能用传统的m-线方法测量。利用分析转移矩阵(ATM)方法研究了渐变折射率波导中的表面等离子波,提出了一种确定波导近表面折射率的实验技术,在波导折射率分布的拟合中,得到了比传统逆WKB方法更为合理的结果。     

近红外车载激光雷达高耐磨双层减反膜

工作波长为905 nm的激光雷达在汽车自动驾驶领域具有强大的应用前景,但工业常用的磁控溅射减反膜,作为其光学窗口表面涂层之一,存在耐磨性不足问题,难以适应恶劣户外环境。采用溶胶凝胶法结合高温固化工艺,为工作波长为905 nm的车载激光雷达减反膜提供高耐磨、低成本的解决方案,并研究了固化温度、盐酸浓度、络合剂存在且低酸浓度下的含水量对TiO2折射率的影响。从反射率、粗糙度、硬度、耐磨性等方面对采用不同底层固化方式的双层减反膜的光学性能和机械性能进行评估,结果表明：当入射光波长为905 nm时,薄膜表现出优良的减反性能,入射角为15°时反射率小于1%,入射角为60°时反射率小于5%,粗糙度最低为0.005μm,基本满足水平视角120°的激光雷达的光学需求。薄膜铅笔硬度达8H,最多能够承受8 000次往复摩擦且无明显损伤,具有优良的适应恶劣环境的能力。     

折射率渐变透镜的数值设计

传统折射率渐变透镜的设计要求初级馈源天线具有稳定的相位中心,这就限制了透镜的应用范围。为拓宽透镜的应用范围,提出了一种折射率渐变透镜的数值设计方法,通过对馈源天线的极化电场离散采样获得相位信息,并据此设计透镜,随后用金属短线结构的新型人工电磁材料来实现这种透镜。这种设计方法简单灵活,对馈源天线没有限制。以经典矩形贴片天线为例,比较了贴片天线和透镜天线的回波损耗和远场方向图,结果表明运用这种方法设计的透镜使贴片天线的增益提高了2 dB,口径效率从62%提高到了99%。     

折射率渐变透镜的数值设计

传统折射率渐变透镜的设计要求初级馈源天线具有稳定的相位中心,这就限制了透镜的应用范围。为拓宽透镜的应用范围,提出了一种折射率渐变透镜的数值设计方法,通过对馈源天线的极化电场离散采样获得相位信息,并据此设计透镜,随后用金属短线结构的新型人工电磁材料来实现这种透镜。这种设计方法简单灵活,对馈源天线没有限制。以经典矩形贴片天线为例,比较了贴片天线和透镜天线的回波损耗和远场方向图,结果表明运用这种方法设计的透镜使贴片天线的增益提高了2 dB,口径效率从62%提高到了99%。     

基于微流控光学可调谐的渐变折射率特性研究

本文基于层流液体的对流扩散效应,提出了一种新型的具有渐变折射率分布特性并且可以实现调节的微腔流体透镜.利用有限元法分析微腔中芯层与包层流体在对流扩散过程达到稳定后的浓度分度,即混合流体的折射率分布,结果表明,分别调节芯层与包层流体的流速,微腔中的流体可以实现不同的渐变折射率分布.同时,本文还分析了即使考虑腔壁与流体之间的黏滞阻力因素,芯层与包层流体的流速组合依然是混合流体折射率分布的决定因素.应用微腔流体透镜的这种调节效果,可以实现不同要求的光束聚焦、分束、偏转等功能,在微流控光学检测系统以及微成像系统中有重要的应用.     

渐变折射率波导的BPM分析

利用BPM对MEMS波分复用系统中的渐变折射率波导的性能进行分析。详细推导了BPM的微分方程,并给出了BPM微分方程的有限差分解的形式。并根据FDBPM对已知折射率分布的径向渐变折射率波导进行数值计算分析,其结果表明,在波长为1.55μm的高斯光束垂直入射的情况下,中心折射率为1.5901,聚焦参数为0.052μm-1,并且半径为3μm的平方律渐变波导中具有快速稳定的、高传输率的高斯基模分布。     

两层介质减反膜及其在半导体光电器件中的应用

本文提出了两层介质减反膜的膜系设计方法,导出了用于半导体激光放大器的最佳减反膜系参数,分析了膜层厚度误差对膜系特性的影响,并在行波半导体激光放大器及光探测器上得到了满意的试验结果。     

渐变折射率平板波导的逆分析转移矩阵方法

利用分析转移矩阵方法，可精确计算任意折射率分布光波导模式的有效折射率。在此基础上，推出了逆分析转移矩阵方法，根据实验测量的导模有效折射率来拟合光波导的折射率分布，取得了比逆WKB方法更为合理的结果。     

Assessing approximate broadband omnidirectional antireflection

By introducing the notion of wavelength- and angle-averaged transmittance, we assess in a systematic way the possibility of achieving approximate omnidirectional antireflection in a wide spectral range by using double-layer systems. We also determine the optimum range of thicknesses for which this broadband omnidirectional antireflection occurs.     

Design of wideband graded-index antireflection coatings at oblique light incidence

We suggest a design method of graded-refractive-index (GRIN) antireflection (AR) coating for s-polarized or ppolarized light at off-normal incidence.The spectrum characteristic of the designed antireflection coating with a quintic effective refractive-index profile for a given state of polarization has been discussed.In addition,the genetic algorithm was used to optimize the refractive index profile of the GRIN antireflection for reducing the mean reflectance of s-and p-polarizations.The average reflectance loss was reduced to only 0.04% by applying optimized GRIN AR coatings onto BK7 glass over the wavelength range from 400 to 800 nm at the incident angle of θ 0=70°.     

Wide-angle and broadband graded-refractive-index antireflection coatings

The design and fabrication of graded-refractive-index (GRIN) antireflection (AR) coatings with wide-angle and broadband characteristics are demonstrated. The optimization of the graded-index profiles with a genetic algorithm is used in the design of the GRIN AR coatings. The average reflectance over a wavelength range from 400 nm to 800 nm and angles of incidence from 0° to 80° could be reduced to only 0.1% by applying an optimized AR coating onto BK7 glass. The optimization of step-graded GRIN AR coating is then further investigated in detail. A two-layer AR coating was deposited by electron beam evaporation with glancing angle deposition technology, and the positional homogeneity was improved by depositing the film from two opposite directions. The microstructure of the AR coating was investigated by scanning electron microscopy, and the residual reflectances of the coating sample are in agreement with theoretical calculations. The optimized GRIN AR coatings are beneficial to increasing the efficiency of light utilization.     

Design of wideband graded-index antireflection coatings at oblique light incidence

We suggest a design method of graded-refractive-index (GRIN) antireflection (AR) coating for s-polarized or p-polarized light at off-normal incidence. The spectrum characteristic of the designed antireflection coating with a quintic effective refractive-index profile for a given state of polarization has been discussed. In addition, the genetic algorithm was used to optimize the refractive index profile of the GRIN antireflection for reducing the mean reflectance of s- and p-polarizations. The average reflectance loss was reduced to only 0.04% by applying optimized GRIN AR coatings onto BK7 glass over the wavelength range from 400 to 800 nm at the incident angle of θ₀ =70°.     

193 nm氟化物增透膜的特性

为了研制低损耗、高性能的193 nm氟化物增透膜,研究了基底和不同氟化物材料组合对氟化物增透膜的影响。在熔石英基底上,将挡板法和预镀层技术相结合,采用热舟蒸发方式制备了不同氟化物材料组合增透膜,对增透膜的剩余反射率和光学损耗等光学特性,以及表面粗糙度和应力等特性进行了测量和比较。在分析比较和优化的基础上,设计制备的3层1/4波长规整膜系AlF3/LaF3增透膜在193 nm的剩余反射率低于0.14%,单面镀膜增透膜的透射率为93.85%,增透膜表面均方根粗糙度为0.979 nm,总的损耗约为6％。要得到高性能的193 nm增透膜,应选用超级抛光基底。     

193 nm氟化物增透膜的特性

 为了研制低损耗、高性能的193 nm氟化物增透膜,研究了基底和不同氟化物材料组合对氟化物增透膜的影响。在熔石英基底上,将挡板法和预镀层技术相结合,采用热舟蒸发方式制备了不同氟化物材料组合增透膜,对增透膜的剩余反射率和光学损耗等光学特性,以及表面粗糙度和应力等特性进行了测量和比较。在分析比较和优化的基础上,设计制备的3层1/4波长规整膜系AlF3/LaF3增透膜在193 nm的剩余反射率低于0.14%,单面镀膜增透膜的透射率为93.85%,增透膜表面均方根粗糙度为0.979 nm,总的损耗约为6％。要得到高性能的193 nm增透膜,应选用超级抛光基底。     

Anisotropic antireflection coatings: design and fabrication

We discuss the design and fabrication of coatings that are antireflecting for p -polarized light at normal incidence and are purposely reflecting for s -polarized light. A single birefringent material, such as obliquely deposited zirconium oxide, forms the layers of the coating. Typical experimental results for a six-layer zirconium oxide anisotropic antireflection coating are R(p) = 0.2% and R(s) = 4.9%. Potential applications of the coatings include polarization-selection devices for lasers.     

薄膜非均匀性及其对增透膜性能的影响

基于非均匀膜理论提出的折射率分层模型,将非均匀膜层分为N个均匀子层,应用光学薄膜特征矩阵对其进行理论分析。应用膜系设计软件模拟ZrO2和CeO2的负非均匀性对增透膜光谱特性的影响。研究结果表明:负非均匀性使多层增透膜的反射率增大,在参考波长处的光谱特性变差,使整个反射光谱曲线朝长波方向漂移,从而导致整个膜系的光谱特性偏离理想情形。     

Single-layer antireflection coatings for GaAs solar cells

Optimal parameters of antireflection coatings for GaAs solar cells are simulated and calculated by the optical matrix approach method. It is shown that by using single-layer Ta₂O₅ and ITO antireflection coatings it is possible to reduce essentially the reflectance from the surface of GaAs solar cells.