CAREER: Ultralow phase noise signal generation using Kerr-microresonator optical frequency combs

自二十年前发明以来，光学频率梳已成为精密测量中最重要的工具之一。它们被用于痕量气体光谱学，用于检测化学危害和与疾病相关的生物标志物，用于恒星光谱学，用于搜索类地系外行星，以及作为光学原子钟的关键部件。尽管它们的使用现在无处不在，但光学频率梳在很大程度上仅限于专门的光学实验室。然而，这种情况正在改变。最近，利用芯片尺度的微环腔和非线性克尔效应实现了光学频率梳。这些“微梳”的前景在于，有可能用芯片上的梳子平台取代专门从事精密测量的研究实验室，这种平台可以在远离光学实验室的地方进行精确测量。与许多精密测量仪器一样，微梳精度受到材料热噪声的限制，这种限制因微孔的小体积而变得更加糟糕。在最近研究材料噪声如何影响梳子精度的基础上，德雷克和她的团队将开发一种基于新型腔体几何结构和梳子操作的微梳子降噪技术。将材料热力学与梳状光的性质分离是将微梳用作最先进的精密测量仪器的一个重要而必要的里程碑。PI提出了深入研究材料热噪声与微谐振器光学频率梳特性的耦合的双重目标，即更好地理解和预测微谐振器光学频率梳中的基本噪声过程，并创建在微波和光学频率上都具有降低热相位噪声的微梳状系统。虽然物质的热力学一般都很清楚，但热噪声和非线性光学的交集在很大程度上仍未被探索。在微梳中，谐振器材料特性中的热波动到梳光特性(微波重复频率或光学梳模)上的噪声的转换高度依赖于梳态的细节，包括拉曼自频移和色散波的存在。该项目通过引入改变这种关系的几何结构和技术，对微谐振器频率梳中的热噪声和频率/相位噪声之间的联系进行了理论和实验研究，并可用于产生超低相位噪声信号。这项研究的总体目标是在具有未来光子集成潜力的低成本室温系统中产生低相位噪声信号(主要是微波信号，也可能是光学信号)。该协会还将为地区STEM教育工作者建立一所暑期学院，专注于基于光学的项目的设计和建设(光学技术发明家和制造者学院，Optima)。与会者将学习光学和光学设计的原理，并将被鼓励创造光学项目，可用作课堂教学材料。从长远来看，PI计划通过与当地制造商空间和阿尔伯克基天文学会等组织合作，将该计划扩展到更广泛的阿尔伯克基社区。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Since their invention two decades ago, optical frequency combs have become one of the most important tools in precision measurement. They are used in trace gas spectroscopy for the detection of chemical hazards and disease-correlated biomarkers, in stellar spectroscopy in the search for Earth-like exoplanets, and as critical components of optical atomic clocks. Although their use is now ubiquitous, optical frequency combs are largely confined to specialized optics laboratories. However, this is changing. Recently, optical frequency combs have been realized using chip-scale microring cavities and the nonlinear Kerr effect. The promise of these “microcombs” lies in the possibility of replacing a research laboratory dedicated to precision measurement with a comb-on-a-chip platform that can perform precision measurements far from the optics lab. As with many precision measurement instruments, microcomb precision is limited by material thermal noise, a limitation which is worsened by the small volume of the microring. Building on recent work investigating how material noise affects comb precision, Drake and her team will develop a technique for microcomb noise reduction based on novel cavity geometries and comb operation. Decoupling material thermodynamics from the properties of the comb light represents an important and necessary milestone for the use of microcombs as state-of-the-art precision measurement instruments.The PI proposes an in-depth investigation of the coupling of material thermal noise to the properties of microresonator optical frequency combs with the dual goals of better understanding and predicting the fundamental noise processes in microresonator optical frequency combs and creating microcomb systems with reduced thermal phase noise in both their microwave and optical frequencies. While the thermodynamics of matter are generally well understood, the intersection of thermal noise and nonlinear optics remains largely unexplored. In microcombs, the transduction of thermal fluctuations in the resonator material properties to noise on properties of the comb light (the microwave repetition rate or the optical comb modes) is highly dependent on the details of the comb state, include the Raman self-frequency shift and the presence of dispersive waves. This project encompasses a theoretical and experimental study of the connection between thermal and frequency/phase noise in microresonator frequency combs by introducing geometries and techniques that alter this relationship and that can be utilized to produce ultra-low phase noise signals. The overall goal of the research is the generation of low phase noise signals (primarily microwave and potentially optical as well) in low-cost, room temperature systems with the potential for future photonic integration. The PI will also develop a summer academy for area STEM educators focused on design and construction of optics-based projects (Optical Technology Inventors and Makers Academy, OPTIMA). Attendees will learn the principles of optics and optical design and will be encouraged to create optics projects that can be used as teaching material in their classes. In the long term, the PI plans to expand this program to the wider Albuquerque community by partnering with organizations such as local area makerspaces and the Albuquerque Astronomical Society.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.