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题名	新型多层膜光栅的设计与性能优化
作者	关贺元
学位类别	博士
答辩日期	2014
授予单位	中国科学院上海光学精密机械研究所
导师	邵建达
关键词	啁啾脉冲方法 多层介质膜光栅 金属多层介质膜光栅
其他题名	Design and performent optimization of novel multilayer grating
中文摘要	多层膜光栅器件结合了光栅和薄膜的优点，在多个领域都有着广泛应用。随着高输出功率激光器的发展，对脉冲压缩光栅的衍射带宽和损伤阈值有着更高要求，因而研究应用于啁啾脉冲放大系统的多层膜光栅器件尤其是多层介质膜光栅和金属多层介质膜光栅，具有非常重要的实际意义。通过理论和实验相结合，针对宽带多层膜光栅器件，系统地研究了优化设计、近电场分布、工艺容差、制备工艺等内容，具体包括如下几个方面的工作： 1）使用模式理论证明模式折射率差对反射式光栅衍射带宽的巨大影响。研究了光栅占空比、光栅周期、刻蚀层材料折射率对模式折射率差的影响；指明高折射率材料刻蚀层光栅容易获得宽衍射带宽原因。 2）计算了占空比、刻蚀深度、剩余厚度、匹配层厚度、高反膜厚度以及周期对宽带多层介质膜光栅衍射光谱影响。增加光栅占空比同时减小光栅脊底角，可以获得宽衍射带宽，为光栅制备提供了指导方向。采用多参数优化方法，设计了顶层为HfO2的梯形脊光栅，其带宽为136nm，具有良好工艺容差。根据设计方案，制备了相应的光栅膜和介质膜光栅。在700nm-900nm范围内，光栅膜反射率达到100%。750nm-878nm范围内，光栅衍射效率高于90%，最高衍射效率为98.5%。损伤阈值测试表明40fs下MDG损伤阈值为0.53J/cm2。 3）详细讨论了金属介质膜光栅近电场特性，具体计算了匹配层厚度、折射率、高低折射率膜层周期对数对光栅脊、匹配层、金属最大电场值影响。随着高低折射率膜层周期对数增大，光栅衍射带宽减小，光栅金属层的电场强度最大值减小。当入射角固定，在中心波长光栅脊、匹配层和金属层的电场强度极大值最小。当入射角度增大，光栅脊、匹配层和金属层的电场强度极大值逐渐减小。根据电场分析结果，提出了结合衍射效率、衍射带宽和近电场强度的光栅优化函数。同时结合HfO2和SiO2各自优点，创新性地设计了高衍射效率、宽衍射带宽三明治结构光栅脊金属介质膜光栅。进一步，提出梯形脊光栅线性外推设计方法，设计了衍射效率高于90%带宽为200nm的梯形三明治脊金属介质膜光栅。制备的金属介质膜在700nm-900nm反射率高于98%。制备的光栅样品在732nm-895nm范围内衍射效率高于90%。 4）不同应用背景的多层膜光栅器件的设计以及工艺研究。首先设计了宽带宽角谱偏振分束光栅，TE和TM偏振的光分别在-1级和0级出射。光栅刻蚀层为HfO2，反射消光比大于20 dB的角度容差为14°，波长容差为46nm。其次针对激光通讯领域的需求，设计了宽带偏振无关光栅。光栅周期为1063.8nm（940l/mm），两种设计方案在1525nm-1575nm波长范围内透射率高于95%。另外，采用磁控溅射，电子束热蒸发，离子束溅射方法制备了预刻蚀多层膜光栅。相比前两种制备方法，离子束溅射方法制备的预刻蚀多层膜光栅致密性好，膜层中没有空洞，对基底的光栅槽型有较好的保形效果，在最外层获得预期的周期性起伏结构。
英文摘要	The multilayer grating combines the benefits of grating and thin film, it is widely used in many fields. The development of high power laser system puts forward higher requirements for bandwidth and laser-induced damage threshold (LIDT) of the pulse compression gratings. Studies on the multilayer dielectric grating (MDG) and metal multilayer dielectric grating (MMDG) have significant practical meanings for the application of multilayer grating in high power laser system. With the combination of theoretical analysis and experiment, the design optimization, electric field distribution, fabrication tolerance and fabrication process are deeply studied in this thesis. Followings are the main contents of the thesis: 1) The modal analysis shows that large difference of effective indices is beneficial for the wideband behavior of reflective grating. The effects of grating duty cycle, period and grating ridge refraction index on the difference of effective indices are studied, and the reason why high index of refraction ridge grating has more broad bandwidth is given. 2) The effects of duty cycle, groove depth, thickness of residual layer, match layer thickness, reference wavelength, slope angle and period on the diffraction spectra of MDG are analyzed. The bandwidth of MDG remains quite large with increasing duty cycle and decreasing slope angle, which gives the guidance for grating fabrication. A trapeziform HfO2 MDG with good fabrication tolerance is designed by using a multiparameter optimization. And the bandwidth centered at 800 nm of MDG reaches up to 136 nm with an average diffraction efficiency of >90%. The multi layer dielectric and MDG is fabricated based on the design. The reflectivity of the multi layer dielectric is 100% in the 700nm to 900nm range. The -1st order DE of MDG exceeds 90% when its wavelength ranges from 750nm to 878nm (128nm bandwidth), and the highest value can reach up to 98.3%. Laser induced damage threshold of 0.53 J/cm2 under 40 fs pulses is experimentally reached. 3) The effects of match layer thickness, match layer refractive index and number of low- and high-index material pairs on electric field in the grating ridge, match layer, and metal layer are discussed in detail. The bandwidth of MMDG and the electric field in the metal layer are reduced by increasing the numbers of low- and high-index dielectrics pairs. The maximum electric field in the grating ridge, match layer, and metal layer reaches its minimum near the central wavelength. Furthermore, the maximum electric field in the grating ridge, match layer and metal layer decreases with the incident angle increas. An optimization method by the integration of the diffraction efficiency, bandwidth, and electric field is proposed. Combining the advantages of SiO2 and HfO2, the trapezoidal grating ridge consists of an HfO2 layer sandwiched between two SiO2 films. The novel MMDG shows broadband, high diffraction efficiency and easy fabrication. A new linear trapezoidal ridge MMDG design method is proposed to reduce the trapezoidal ridge grating design difficulty and give the guidance for grating fabrication. The bandwidth of the designed trapezoidal ridge MMDG reaches 200 nm. The -1st order diffraction efficiency of MMDG exceeds 90 % over the wavelength range of 732nm to 895nm. 4) A reflecting polarizing beam splitter (RPBS) grating is designed to reflect the transverse electric wave in the -1st order and the transverse magnetic wave in the 0th order. The HfO2 RPBS grating exhibit high diffraction efficiency and extinction ratios within a wide angular tolerance (14.5°) and broad wavelength band (46 nm). Polarization independentoptical high transmissivity gratings are designed to meet the requirements in laser communication systems. The transmissivity of two 1063.8nm period designs exceeds 95 % over the wavelength range of 1525nm to 1575nm. The pre-etching multilayer gratings are deposited by magnetron sputtering, electron beam evaporation, and ion-beam sputtering deposition. Compared with the other two fabrication methods, the pre-etching multilayer gratings deposited by ion-beam sputtering deposition are dense, good grating shape-keeping, holes free and easily periodical structure obtainment.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/15854]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	关贺元. 新型多层膜光栅的设计与性能优化[D]. 中国科学院上海光学精密机械研究所. 2014.

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