亚波长光栅微环谐振器包络谱调控机理及折射率传感特性研究

On-chip refractive index sensing has broad application prospects in the fields of environmental monitoring, health diagnosis, food supervision and safety inspection, etc. Currently, the refractive index sensor on silicon platform has become a research hot spot due to its capacities on intelligence, miniaturization and integration. However, it has got a bottleneck in the development, that is, the sensitivity and the measurable range cannot be improved simultaneously. From the intrinsic formation mechanism of the envelope spectrum of microring resonators, in this project, we propose to regulate the envelope spectrum of a subwavelength grating microring resonator (SWG-MRR) by modifying the periodic units of a sub-wavelength grating (SWG), and consequently improve the sensing performance of the SWG-MRR. The main research contents of this project are as follows: We study the influence of the periodic units of the SWG on the modal field distribution, loss, coupling and dispersion characteristics of the SWG-MRR, and further, the dependence of the SWG-MRR envelope spectrum on these characteristics. From the intrinsic formation mechanism of the envelope spectrum, we reveal the regulation principles of the periodic units of the SWG on the envelope spectrum. We research the dependence of sensing performance on the envelope spectrum, and by regulating and optimizing the envelope spectrum, we improve the sensitivity and the measurable range simultaneously. Work in this project can provide new ideas for breaking the bottleneck of refractive index sensing, and is of great significance for the development and application of on-chip sensing systems.

片上折射率传感在环境监测、健康诊断、食品监督和安全检查等领域有着广阔的应用前景，具有智能化、微型化、集成化等优点的硅基折射率传感器已成为当前研究的热点，但它的发展遇到瓶颈，即传感灵敏度和可探测范围无法同时提升。本项目基于微环包络谱的内在形成机制，首次提出利用亚波长光栅周期单元特征对亚波长光栅微环包络谱进行调控，进而实现其传感性能的提升。本项目研究内容主要包括：研究亚波长光栅周期单元结构特征对亚波长光栅微环的模场分布、损耗、耦合和色散特性的影响规律，以及这些特性对亚波长光栅微环包络谱的影响规律，从包络谱的内在形成机制上揭示亚波长光栅周期单元特征对包络谱的调控机理；研究传感性能与包络谱的依赖关系，利用包络谱的调控和优化实现传感灵敏度和可探测范围的同时提升。本项目研究可为突破折射率传感的瓶颈提供新思路，对片上传感系统的发展和应用具有重要意义。

硅基折射率传感器因其微型化、集成化、低成本、与现有微电子工艺相兼容等优势成为了片上传感系统中关键器件的强力候选。面对军事国防、环境监测、食品安全、医疗保健等领域的应用需求，本项目针对硅基微环折射率传感器的传感灵敏度和可探测范围不可兼得的发展瓶颈问题，开展了亚波长光栅微环包络谱调控机理及折射率传感特性研究。主要研究内容有：通过改变亚波长光栅周期单元结构实现微环模场分布、损耗和色散特性控制，进而对其包络谱特征进行优化，掌握亚波长光栅周期单元结构特征对微环传输特性的控制规律，揭示微观结构特征对器件宏观传输特性的调控机理；研究并掌握亚波长光栅微环包络谱特征对其传感性能的影响机制，从包络谱探测传感的内在机制上研究传感灵敏度的提高和可探测范围的拓宽；制备基于亚波长光栅微环的折射率传感器，实验验证其折射率传感性能。代表性成果包括：利用亚波长光栅波导构建了色散型微环，揭示了该器件的包络谱形成机制，利用包络谱追踪实现了兼具高传感灵敏度和宽可探测范围的折射率传感，实测最高传感灵敏度为790 nm/RIU；系统研究了包络谱谱线特征对传感性能的影响规律，结果显示，环程振幅传递因子和振幅自耦合系数的色散特性和它们随外界折射率的变化率均影响其传感特性。在该项目的资助下，发表期刊论文8篇，其中SCI收录5篇，EI收录1篇，中文核心收录2篇，做会议报告1次，申请国家发明专利1项，培养硕士研究生4人。本项目研究的基于亚波长光栅微环谐振器包络谱调控机理及包络谱探测传感机制、制备技术和检测方法对实现硅基集成型传感器的器件化以及片上光学传感系统的实用化、产业化具有重要的科学意义和实用价值。

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