基于波导多模干涉的全光正交变换器件

All optical orthogonal transforms are very useful in various telecommunication systems, such as radio over fiber (ROF) system, microwave and milli-wave communication system, and novel ultra high speed optical communication systems. Therefore they have received signicant attentions..A novel approach to realize all optical Hadamard transforms has been recently proposed based on the multimode interference couplers.However, it has not been used for other orthogonal transforms yet and is lack of systematic design methodology. .In this proposal, we propose to realize novel orthogonal transforms based on the MMI couplers. By tuning the phase shifters and other parameters of the MMI coupler device, novel orthogonal transform devices are formed. The theoretical study on the device performance will focus on the comprehensive coupled mode theory, which will not only consider the multimode coupling, but also includes the nonlinearity and random variation of the physical parameters. The experimental study will focus on the fabrication of the device based on the silicon on insulator (SOI) materials. After careful optimization of the device topology to reduce the coupling loss, a sample chip is expected to be fabricated using this fabrication technology..This research will enable the ultra-high speed all optical digital signal processing in the various telecommunication systems and make the system integrated with the current optical devices and the integrated electronic circuits.The outcome is of significant value to the scientific and engineering communities.

全光正交变换在各种通信系统（如无线通信系统、微波毫米波系统、和光纤通信系统）中具有广阔的应用前景，因此逐渐得到国内外的关注。最近一种基于多模干涉波导的新型器件被提出用来实现全光哈达玛变换。但此方法还尚未被用来实现其它的正交变换，并且缺乏系统性的设计方法。本课题拟开展对于该器件的研究，通过调节各种多模干涉波导物理参数及相关的移相器的相位，寻找新的途径和方法实现多种全光正交变换。在理论研究方面，计划从多模干涉型波导的耦合波模型出发，建立描述波传输中非线性效应、多模耦合及参数随机涨落的详细模型。在器件制备上，采用SOI材料和较为成熟的工艺流程，通过优化物理设计方案，降低耦合损耗，在SOI材料上实现该器件的样片。该课题的研究成果，将帮助实现多种通信系统中全光化超高频数字信号的处理，并且有助于实现该系统和现有光器件和电路的集成化，对于科学研究和工程应用都有重大的意义。

本项目实施期间，共计发表、录用第一作者兼通信作者SCI二区期刊论文11篇，会议论文1篇。申请专利3项。开展多模波导模式耦合理论研究，重点研究了随机效应对于波导模式的影响，并且应用该理论分析自由空间中大气折射率的随机涨落对于空间模式传输上的影响；将模式耦合理论的研究扩展到多芯波导上，得到了多种多芯波导的“超模”，该方面的研究被进一步扩展到多芯波导的模分复用器件的研究上；该方向上在Optics Express上发表论文3篇。开展多模波导中非线性效应对于系统性能的影响研究，重点应用Volterra序列，得到了非线性多模干涉波导方程的一个解析解；研究了多模波导中拉曼效应，并且得到了一个优化拉曼信号放大效应的解析方法；该方向上共计发表论文2篇，其中在IEEE Journal of Lightwave Technology上发表论文1篇，在Optics Express上发表论文1篇。开展基于多模干涉型波导新型正交变换器研究，在该方向上主要提出了多种基于多模干涉波导的新型模分复用的器件、可控功率分配器件等新型正交变换器件，在该方向共计录用、发表期刊论文6篇，其中在IEEE Photonics Technology Letters上发表、录用论文4篇，在Optics Express上发表论文2篇。申请国内专利3项。相关研究成果对于高集成度的高速光信号处理器件的研究具有较大的理论和应用价值。