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基于狭缝波导的光器件研究
Study of Slot-based Optical Devices
【作者】 肖司淼;
【导师】 杨建义;
【作者基本信息】 浙江大学 , 微电子学与固体电子学, 2010, 博士
【摘要】 现代大容量、高速的光通信网络的发展离不开集成光子器件的应用。同时,光子器件的应用还渗透到如片上系统光互连、光伏、显示、传感等诸多领域。并向小型化、集成化、与节能化方向发展。硅材料以其高折射率差、低成本、有成熟的微电子制作平台等优势,越来越得到广泛关注,并取得了一系列重要的技术突破。然而其在有源器件的制作方面仍受限于本身的物理性质。为了利用硅材料卓越的无源特性和与微电子器件的兼容性,并弥补其物理性质的不足,近年来人们尝试通过其他材料与硅的混合集成实现优势互补。如将Ⅲ-Ⅴ族化合物半导体激光器、探测器与硅器件混合集成,或通过狭缝波导这一特殊结构直接在硅波导上实现良好的有源特性。特别是后者,成本更低,实现更为简单。基于此,本论文概括了狭缝波导的基本原理和各项应用。针对目前研究现状,提出了自己的一些分析和实验尝试,主要创新和贡献在于:1.基于马赫-曾德干涉仪原理,通过在狭缝波导中填充电光聚合物的方法,提出了一种高速电光硅基光开关,长度几百微米,集总型电极下调制频率可达83GHz,功耗仅为37fJ/bit,均优于目前普遍研究的载流子色散型同类器件。2.针对长期以来硅基Y分叉型数字光开关性能不理想、尺寸过大的问题,同样通过聚合物的填充,提出了一种高速的紧凑型狭缝波导数字光开关。并探讨了多狭缝引入带来的性能改进。3.针对目前垂直型狭缝波导在刻蚀时工艺要求过高的问题,提出了一种利用反偏p-n结构成的改进电极结构。它能够在刻蚀深度不理想,甚至是脊型狭缝波导的情况下,保证两侧硅电极之间的电绝缘。具有工艺容差大,制作简单的特点。4.提出了基于垂直狭缝波导的对称和非对称的马赫-曾德型微流传感器,并采用折叠型波导设计,大大缩短了干涉型传感器的长度,理论上具有较高的传感灵敏度。分别采用欧洲纳电子研究机构IMEC的0.18μm工艺线和上海中芯国际的0.18μm工艺线代工制作,工艺水平居国内前列。5.尝试在实验室制作填充聚合物的水平狭缝波导,取得了一些阶段性结果,探讨了经验与不足。
【Abstract】 Integrated optical devices plays an important role in the development of modern large-capacity and high-speed optical network,and in the fields of on-chip optical interconnection, photovoltaic,display, sensing,etc. It moves now to be more compact,integrated,and energy-saving.Silicon, as a material with large refractive index difference, low cost and being compatible with the mature micro-electronics platform, is getting more and more attention, and has already achieved lots of technological breakthroughs. However the active devices based on it are still underdeveloped for the limitation of the corresponding physical properties.In order to get use of the excellent passive characteristics of silicon and its compatibility with the micro-electronic devices, meanwhile overcoming the physical shortage of it,in recent years people are trying to hybrid integrate silicon with other materials to complement advantages.For example to integrate silicon devices with lasers and photodetectors made byⅢ-Ⅴsemiconductors,or to realize active characters on silicon platform by using slot structure which has a lower cost and is more simple. In this thesis,first the basic principle of the slot structure and its applications are summarized, and then a series of analyses and experimental attempts are proposed. The main innovation and contribution are:1.Based on the principle of Mach-Zehnder interference, a high-speed electro-optical silicon optical switch is proposed by filling electro-optical polymer inside the slot structure of the interference arms.The device length is only few hundreds micrometers,the modulation frequency can achieve 83GHz even by using the lumped electrodes,and the power consumption is only 37fJ/bit,much advanced than the carrier dispersion type devices studied till now.2.In order to overcome the drawbacks that the performance of the Y-branch digital optical switch is not very good and the device size is large, also by filling electro-optical polymer,a high-speed compact silicon digital optical switch with the slot structure is proposed. Then the performance improvement by introducing the multi-slot structure is discussed.3. Since it is hard to etch the slot through for the vertical slot structure, an improved electrode with reverse p-n junction is proposed. It can maintain electrical isolated for the unideally etched case, and even for the rib-type slot structure. The fabrication tolerance of it is large and it is easy to realize.4.Symmetric and asymmetric Mach-Zehnder type micro-fluidic sensor based on the slot structure is proposed, also by folded interference arms,the device length can be largely shortened, and the theoretical sensing sensitivity is high. We use the foundry of IMEC in Europe and SMIC in Shanghai for fabrication. The typical width is 0.18μm, which is advanced in domestic.5. Tried to fabricate horizontal slot structure filled with polymer in our laboratory. Some phasic achievements are gained, the difficulties and the possible methods for ameliorating are discussed.
【Key words】 silicon photonics; slot waveguide; optical switch; micro-fluidic sensor; Mach-Zehnder; digital; foundry;