【作者】 倪玮；

【导师】 吴兴坤；

【作者基本信息】 浙江大学 ， 光学工程， 2009， 博士

【摘要】 最近,处理器速度和处理能力的迅速发展,显著提高了模块、线路板、背板和机柜之间的数据传输速率。在先进的高性能计算系统、交互多媒体以及高速交换网络通信系统中,数据传输速率已经超过了3 Gbps。同时,更高数据传输速率的需求,也导致芯片内部和芯片间电互连方案的复杂度和成本日益增加。为了解决上述问题,世界上的主要研究机构都在大力发展光互连作为替代铜线的可行方案。光学互连技术能提供更高的数据带宽,扩展的I/O密度,更低的串扰,并且无电磁交扰现象,布线的重量和尺寸都能得到降低。然而,光电组件、模块、连接器,以及用于短距离通讯(＜1m)传输介质的相对高成本,都阻碍了光互连在先进计算机和通信系统中的应用。作为全光互连的过渡阶段,光电混合印刷电路板的研制,能够在现阶段充分利用已有的集成电子制造技术,又通过光互连在一定程度上提升了系统性能。但是如何将光层高效率低成本地集成到印刷电路板中也一直是研究的难点和重点。本文在分析短距离光互连、尤其是基于高聚物波导的光互连应用于芯片间互连时所面临的问题的基础上,对单层光互连中光导层与光源/光接收器之间的端口耦合结构、平面内布线准则,多层光互连中层间耦合结构以及光互连用无源光器件等进行了系统深入的研究,提出了切实可行的技术方案,并通过软光刻技术实现了高精度低成本的互连线路与无源光器件的实物制作。本文主要在以下几个方面取得创新性成果:(一)应用软光刻法作为短距离光互连的主要技术实现途径,不仅提供简易、低成本、高质量的互连线路制作方案,上述方案及其成品均能很好地兼容于现有电互连系统。基于软光刻成功试制出结构紧凑型高聚物光功率分配器,也为光互连用无源光器件提供了低成本的量产解决方案。更重要的一点是,软光刻结合微刻与抛光可以克服其他光刻胶制模法边墙粗糙的问题,从而极大地降低了因边墙粗糙引起的波导传输损耗,对低误码率短距离光互连是非常有利的;(二)设计并制作了由矩形波导,光束耦合适配段和端面反射器组成的一体化集成型端口耦合结构,用于光互连中光导层与光源/光接收器之间的无源耦合,并被证明该结构具有较高的耦合效率和偏差冗余度;(三)在实验和理论分析的基础上,研究了单层光互连线路中交叉和分叉节点的特性。对于不同横截面矩形波导结构在交叉布线时呈现串扰与交叉角度的相关性进行了分析,并与实验结果作了比较。对于分叉节点找到了合适的零泄漏分叉角度,并对多模波导在短距离应用上的特性也进行了深入研究,所得结果对将来光集成型印刷电路板,尤其是基于软光刻技术的光互连结构具有高程度的适用性;(四)提出了一种基于S形弯曲波导的层间垂直耦合结构,该结构具有较低的传输损耗,且结构简单。利用软光刻技术的制作流程使得上述耦合互连设计,在连接损耗以及用于高带宽印刷电路板方面,都比传统设计和制作方法具有明显的优势。更多还原

【Abstract】 The rapid advance in the processor speed and processing power in recent years has dramatically increased the data transfer rates between modules, boards, backplanes and cabinets. In the advanced high performance computing systems, interactive multimedia and high speed switching network communication systems, data transfer rates are exceeding 3 Gbps; nevertheless, the demand for higher data transfer rates and the increasing complexity and costs in finding electrical solutions for intra- and inter-chip interconnect have led to several major laboratory activities worldwide to develop optical interconnect into a viable alternative to the copper solution.The optical interconnect technology offers higher data bandwidth, increased I/O density, reduced crosstalk, ease of impedance control, insensitive to EMI, and reduced weight and size of cabling. The applications of optical interconnect in advanced computers and communication systems, however, have been hindered by relatively high costs of optoelectronic components, modules, connectors, and the transmission media for relatively short range communication of less than one meter. For final aim of full-optical interconnection, a strong focus has now been placed upon optics-embedded printed circuit boards (PCBs), or hybrid electro-optical PCBs in which the optical and electrical layers are integrated into one board, as their fabrication can take advantage of existing PCB manufacturing processes while it can also provide better system performance. To a large extent, a high efficient and low-cost way of integrating the optical layer into or on the conventional printed circuit board (PCB) is a key technical roadblock.In this dissertation, based on investigation of problems facing short-range optical interconnection, especially polymer-waveguide-based optical interconnection for chip-to-chip interconnection, circuit termination coupler for waveguide/transceiver coupling, horizontal circuit layout criteria, vertical coupling structure for multilayered optical interconnect and passive optical components are deeply researched, while the practical technological schemes are proposed, then experimental prototypes of high precision, low-cost interconnection circuits and passive optical components are fabricated by using soft lithography. The main innovative achievements of this dissertation are presented as following:1. The primary application of soft lithography to short-range optical interconnection is not only demonstrated to provide simple, low cost and high quality interconnection circuit fabrication schemes, but also has a high compatibility to the present electrical interconnect systems. The soft-lithography fabrication process of the coupling interconnection design allows for significant advantages over traditional designs and fabrication methods in terms of insertion loss as well as 3D integration capability, when used in high-bandwidth PCBs. A novel soft-lithography-based compact-size polymeric multimode power splitter is successfully fabricated, which suggests a solution to low cost and mass production of passive optical components for optical interconnection. More important, combined with micro-engraving and polishing, soft lithography can overcome the roughness sidewall problem caused by other photosensitive-resist-based molding methods, so propagation loss of the waveguide can be greatly reduced which is valuable for low-BER short-range optical interconnection.2. A low-cost, versatile circuit termination coupler featuring a monolithic integration of a polymeric waveguide, beam ducts, and end-reflectors is designed and prototyped, capable of easing the coupling between transceiver and waveguide significantly. It is also demonstrated to be capable of sustaining high misalignment errors whilst maintaining a reasonable coupling efficiency.3. Characteristics of crossing and branching nodes in monolayer soft-lithography-based polymer optical interconnects are investigated with experimental and theoretical analysis. The theoretical crosstalk, as calculated by a function of crossing angle, is determined for a set of interconnect pairs with varying cross-sections, and is compared with experimental measurements. Furthermore, a suitable no-leakage branching angle was found for branching node and the effects of short-distance mode scrambling in highly multimode polymer waveguides are studied in detail. The results have a high degree of applicability to future optics-integrated PCBs featuring soft-lithography-fabricated interconnect structures.4. A layer-to-layer coupling featuring a simple S-shaped structure with lower insertion loss is proposed for multilayered optical interconnect. The soft-lithography fabrication process of this coupling interconnection design allows for significant advantages over traditional designs and fabrication methods in terms of connecting loss as well as 3D integration capability, when used in high-bandwidth printed circuit boards.更多还原