基于激光消融技术的光波导散射损耗优化

论文总字数：21420字

摘 要

在集成光路中，光波导易于与其他光电元件集成，损耗小，制作成本低廉，是非常重要的，但是集成光路的发展进度远远不够。在光波导中传输的时候，光子由于被吸收，散射和辐射，降低了传导能量。其中，散射损耗一般是在介质波导中。损耗的原因则应该归结于波导的缺陷。由于波导层内存在缺陷而产生的损耗为体散射损耗^[1]。体散射损耗一般比较小，通常不去考虑。需要考虑的是表面散射损耗。而在一些研究中发现越光滑的波导表面，其损耗会越低。因此，通过一些方法使波导表面更加光滑，可以有效减小光波导器件的散射损耗。在制作光波导器件的时候，由于微加工工艺导致的波导侧面粗糙，而粗糙波导表面将导致光波导传输损耗增大，为了减小光波导器件的表面粗糙度从而减小散射损耗，可以尝试采用聚焦二氧化碳激光器对制备的光波导进行激光加热消融，通过控制激光器的功率和工作时间，来对波导表面进行照射使之光滑，从而减小光波导器件的损耗。首先通过光刻、刻蚀等微加工工艺制备光波导结构；其次通过原子力显微镜等测量制备波导的表面粗糙度；通过CCD数字成像法测量制备光波导的传输损耗；取同一批制备的光波导进行激光消融实验，通过控制激光功率和照射时间，研究这些激光参数对波导表面粗糙度的影响，并通过原子力显微镜进行粗糙度表征；对激光消融处理的光波导进行传输损耗测量，并与未经激光消融处理的光波导传输损耗比较，分析实验结果。光波导结构的制作过程包括光波导的设计和微加工工艺制备。主要过程有：基片处理，二氧化硅下包层制备，芯层制备，波导掩膜层，芯层刻蚀，上包层制作，器件切割，器件抛光研磨。搭建好激光和传输损耗测量装置后，先使用样品进行试测，来选取一个合适的激光器的功率和照射时间。此后通过激光照射，与无照射的形成对比，进行数据测量，计算传输损耗值。

关键词：光波导； 传输损耗； 粗糙度； 激光消融

Laser Ablation Techniques To Optimize the Optical Waveguide Scattering Loss

Abstract

In integrated optics, optical waveguide components with low loss and low production cost is very important, and can be easily integrated with other optoelectronic components, but the development of integrated optics progress is far from enough. In optical waveguides, photons due to absorption, scattering and radiation, reduces the transmission energy. Among them, the scattering loss is usually induced in the dielectric waveguides. The cause of the loss should be attributed to the defect in waveguides. It is due to the defects in the waveguide layer and the loss of body scattering loss. Body scattering loss is generally small and usually neglected. Only the surface scattering loss is needed to be considered. And in some studies, it is found that the losses in the waveguides with smooth surfaces will be lower. Therefore, making the waveguide surface more smooth by some methods, can effectively reduce the scattering loss of optical waveguide devices. In the fabrication processes of optical waveguide devices, the waveguide roughness is due to the micro processing technology, and the rough surface of the waveguide will lead to the increasing of propagations loss. In order to reduce the surface roughness of optical waveguide devices so as to reduce the scattering loss, CO₂ laser is adopted to improve optical waveguide’s surface quality by the laser melting. By controlling the laser power and working time to illuminate the waveguide, surface roughness of the optical waveguide devices can be reduced. First optical waveguide structure was fabricated by micro processing technology such as the photolithography and etching; The transmission loss can be measured by CCD digital imaging method; In the optical waveguide laser ablation experiments, by controlling the laser power and irradiation time, the impact of these waveguide laser parameters of surface roughness was studied. And the optical waveguide transmission losses were measured and compared for the optical waveguides with and without laser ablation treatments. The fabrication processes of the optical waveguide structure including the design of optical waveguide and micro machining processes. The main processes are: substrate processing, silicon dioxide fabrication, core layer deposition, waveguide mask layer, core layer etching, cladding layer deposition, cutting device, polishing device. Build selecting a suitable laser power and irradiation time, optical waveguide wall roughness decreased obviously and the optical waveguide transmission loss can be reduced.

Keywords: Optical waveguide; Transmission loss; Roughness; Laser ablation

目录

摘 要 1

Abstract 2

第1章 绪 论 4

1.1 引言 4

1.2 主要实验内容 5

1.3 工作内容和结构安排 5

第2章 概述 6

2.1 光波导的概述和分类 6

2.2 光波导的损耗 9

2.2.1 光的折射和反射 9

2.2.2 光波导模式 10

2.2.3光波导损耗 11

2.3 损耗测量 12

2.4 波导制备 13

2.5 激光器的选择 14

2.6 CCD数字图像法 14

2.6.1 CCD数字传感器 14

2.6.2 原子力显微镜 14

2.6.3 SEM电子扫描显微镜 15

第3章 实验 16

3.1微加工工艺制备光波导结构 16

3.1.1 矩形波导的设计 16

3.1.2 矩形波导的制备过程 16

3.2激光光路搭建与传输损耗测量装置 18

3.3二氧化碳激光器功率与时间 19

第4章 结论 22

致谢 23

参考文献 24

第1章 绪 论

1.1 引言

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