基于新型硅基波导结构的中红外波段频谱变换研究

Mid-infrared band within 2-5 μm has huge potentials to free-space optical communications, laser radar, laser guidance, and remote sensing. However, photonic technologies and devices in this band are very limited. In particular, the integrated mid-infrared photonic devices are almost blank. As the bridge of the mid-infrared band and the telecommunication band, mid-infrared spectral conversion is considered as the basic key technology to develop mid-infrared devices and applications using the mature technologies in the telecommunication band. Targeting to high-performance silicon-based mid-infrared spectral conversion, we will design and fabricate novel silicon-based waveguide structures and use them to realize mid-infrared spectral conversion. From the coupled wave theory, the theoretical model of mid-infrared spectral conversion will be established by considering special effects in silicon waveguides in this band. Novel silicon-based waveguide structures with new substrates such as sapphire for low propagation loss, and silicon-based composite waveguide structures, incorporating novel materials such as graphene, metals, and polymers, for high efficiency and broad bandwidth will be designed and fabricated. Also, mid-infrared spectral conversion will be experimentally demonstrated by using the designed silicon-based waveguides, and intra-band and inter-band data exchanges will be further realized. These investigations will be the first exploration on the silicon-based mid-infrared spectral conversion in our country. They will lay a firm foundation for the development of the silicon on-chip photonic devices in the mid-infrared band and be of great significance for various mid-infrared applications.

2-5μm的中红外波段在空间光通信、激光雷达、激光制导、遥感等方面具有巨大应用潜力，但目前中红外光学技术和器件还不成熟，特别是集成型中红外光子器件基本空白。作为中红外波段和通信波段的桥梁，中红外频谱变换是借助通信波段的成熟技术发展中红外波段器件和应用的核心关键技术。本项目以高性能硅基集成型中红外频谱变换为目标，设计研制新型的硅基波导结构并实验实现中红外频谱变换：从耦合波理论出发，考虑中红外波段硅基波导中的特有效应建立中红外频谱变换的理论模型；选择氧化铝等新衬底、设计新型波导结构降低传输损耗，结合石墨烯、金属、聚合物等新材料设计硅基复合波导结构提升变换效率和带宽等特性；基于硅基波导实验实现中红外频谱变换，并验证中红外波段及其与通信波段之间的数据交换。本项目将是国内对硅基中红外频谱变换的首次探索，可望为中红外波段的硅基片上光子器件的研制奠定坚实基础，对开展中红外波段的各种应用具有重要意义。

2-5 μm的中红外波段在空间光通信、激光雷达、激光制导、遥感等方面具有巨大应用潜力，但目前中红外光学技术和器件还不成熟，特别是集成型中红外光子器件基本空白。作为中红外波段和通信波段的桥梁，中红外频谱变换是借助通信波段的成熟技术发展中红外波段器件和应用的核心关键技术。本项目研究了基于新型硅基波导结构的中红外频谱变换，建立了硅基波导中红外频谱变换的理论模型，设计并研制了多种新型的硅基波导结构，并实验实现了中红外频谱变换，主要内容包括：1）从耦合波理论出发，在弱导和强导条件下分别建立了中红外波段硅基波导中四波混频的标量和矢量理论模型，分析了频谱变换效率、变换带宽与波导参数以及入射泵浦光条件之间的关系。2）以获得高效率、大带宽的中红外频谱变换为目标，设计了硅基悬空波导、硅锗集成波导、石墨烯-硅基复合波导等多种硅基波导结构，通过强场限制有效提高了频谱变换效率，同时通过色散优化，获得了宽带性能。3）探索了相关波导结构的集成制作工艺，研制了用于中红外频谱变换的硅基悬空波导、石墨烯-硅基复合波导、硅-富硅氮化硅集成波导等多种中红外高非线性波导结构，并进行了性能测试。4）利用研制的硅基复合波导结构，搭建相应的实验装置，在中红外波段实验观测了硅基波导中的四波混频非线性效应，并测量了频谱变换的效率和带宽。本项目是国内对硅基中红外频谱变换的首次探索，为中红外波段的硅基片上光子器件的研制奠定了基础，对开展中红外波段的光纤通信、间接探测等各种应用具有重要的借鉴意义。