基于准连续中红外频率梳的微纳生化传感关键器件研究

The mid-IR wavelength range is very important for sensing and analyzing a wide range of materials including gas molecules, organic compounds, and biological materials. The vibrational modes of most molecules have spectral fingerprints in this wavelength range, which can be used not only to identify different materials but also to analyze chemical bonds and track conformational change in molecules. Silicon photonics is widely accepted as the prevailing platform for large-scale optoelectronic integration. This project proposes an integrated device, which allows very complex systems to be integrated on a single chip and perform different tasks simultaneously. The proposed device, which combines the ring based frequency comb generator and slot waveguide, will overcome the faults of mid-infrared detector available nowadays in cost and scale. This project which regards both theory and experiment, will reduce the impact of group velocity dispersion, compensate the nonlinear detuning of pump component in the micro-ring cavity, and avoid the electric field mismatch in micro-structure. In this project, the technology of “suspending waveguide”, the technology of generating pump laser around 3.5μm by optical parametric oscillator, and the technology of compensating the pump component detuning in comb generation will be studied in detail to enhance the energy efficiency in sensing. Based on the research mentioned above, this project will generate frequency comb with high spectral resolution over a wide wavelength range, and give help in developing optoelectronic integrated bio-chemical sensing with ultrahigh sensitivity.

3-5μm波段包含众多有机大分子基团的特征波长，是光学传感的理想波段，而硅则是开发集成光学器件的首选材料。本项目针对现有生化检测设备体积庞大、无法实现微量检测等缺点，拟将硅在集成光学领域的优良特性同3-5μm中红外波段在生化领域巨大的应用前景相结合，利用微环谐振腔激发频率梳，使其在狭缝波导中与待测物相互作用，并用微加热器调节频率梳元素频率，覆盖此波段所有波长，通过光谱分析实现高灵敏度传感。本项目理论与实验并重，将降低群速度色散对宽谱频率梳形成的影响，补偿泵浦频率在谐振腔中的非线性相移失谐，分析光信号在各器件传输模式场匹配的机理，利用光学参量振荡，实现频率梳泵浦用3.5μm波长可调谐光源的激发，探索“悬空波导”制作和泵浦频率非线性相移补偿技术。最终提高光能利用率，激发高稳定性、高分辨率、宽光谱范围光学频率梳，与狭缝波导结合用于微纳生化传感，为开发下一代光电集成，高灵敏度生化传感器件创造条件。

3-5μm波段包含众多有机大分子基团的特征波长，是光学传感的理想波段，而硅则是开发集成光学器件的首选材料。本项目利用微环谐振腔激发频率梳，使其与待测物相互作用，通过光谱分析实现高灵敏度传感。本项目研究了谐振腔结构、泵浦光强度、泵浦光与谐振腔间耦合系数等参量对频率梳产生的影响，为设计谐振腔结构、优化群速度色散提供了依据；为了补偿泵浦频率在谐振腔中的非线性相移失谐，设计并优化了耦合双环谐振腔结构，研究了其中的频率梳产生机理，分析了谐振腔间耦合强度对各器件中光电场模式匹配效应的影响，补偿了非线性相移失谐，并用3.8μm波长激光做泵浦源激发频率梳，光谱范围覆盖3-6μm波段，为开发下一代光电集成，高灵敏度生化传感器件创造条件；深入研究了在微环谐振腔中四波混频等光学参量振荡效应的产生机理，推导了四波混频信号产生的效率与泵浦光间的关系，并制作微环谐振腔加以验证，实验发现在低泵浦功率作用下，四波混频信号频率产生效率与理论值接近，随着泵浦功率的提高，测量值逐渐小于理论值；研究了定向耦合器工作过程中的电场模式变化，构造了|Ksinφ|参量以便精确确定谐振波长；设计了光栅辅助型定向耦合器，实现了泵浦信号的特异性耦合；提出了“强度比例法”可用于波长定位，提高测量精度；形成了一套化学、生物检测方法，并以包覆聚乙烯乙二醇（PEG）的Fe3O4为例进行了传感研究。经过对四波混频效应的深入研究，采用耦合双环谐振腔结构，大幅提高了光学频率梳的激发效率，实现了对化学、生物分子的检测。共计在国际期刊上发表SCI检索学术论文6篇，申请国家发明专利9项，其中3项已获授权。参加IEEE Photonics Conference一次，并做口头报告。本项目研究成果做为传感型光纤传感系统的一种，参与建设了《浦口-天津大学光纤传感展示体验园》，向大众普及微纳光学，普及光学传感知识。