基于相位操控的新型双光梳光源的研究

The optical frequency combs based on the unique combination of femtosecond pulse laser and precise time and frequency control technology, improve the precision of the timing and frequency to an unprecedented level. In particular, dual-comb spectroscopy is an emerging novel powerful tool in recent years. This technology exploits the frequency accuracy, frequency resolution, and brightness of the frequency combs for high-accuracy, high-resolution, and broadband spectroscopy in real-time. However, the full potential of the dual-comb spectroscopy has not been realized especially in precision measurement yet, mostly because of the limitations in controlling accuracy of the combs and mutual coherent controlling between two combs. In this project, the study of the phase noise suppression for the femtosecond comb is proposed and we will develop the ultralow noise frequency comb based on the femtosecond fiber laser. Then, we will explore a novel approach for improving mutual coherent between two combs with combination of optical frequency synthetization and feed-forward control. By using this approach, the limitations due to the relative timing and phase fluctuations between the two combs can be overcome, which allows us to resolve individual comb lines and achieve high-speed optical sampling. The high-accuracy multiheterodyne spectroscopy will be obtained with recorded amplitude and phase information. Finally, the obstacle for high-resolution dual-comb spectroscopy, caused by phase noise and relative linewidth, can be accessed by precision control technology of ultrafast optics.

结合飞秒脉冲激光与时-频域精密控制技术发展起来的光学频率梳，将时序和频率的控制精度提升到了前所未有的量级。近年来发展起来的双光梳光谱技术，结合了光学频率梳高频率精准、高频率分辨能力、高亮度的特点，为开展高精度、高分辨、宽光谱快速分析提供了崭新的技术手段。然而现有的双光梳光谱技术仍未达到精密测量所需精度的要求，关键问题之一是光梳光源的控制精度和双光梳相对相位操控技术的局限。本项目拟将开展飞秒光梳相位噪声抑制技术的研究，结合光学频率传递和前向反馈式载波包络相位控制技术，探索双光梳相对相位精密控制的新方法，消除飞秒脉冲定时抖动和瞬时相位波动对频谱分辨率的制约，形成新型梳齿可分辨的高精度双光梳光学快速采样技术，实现相干多外差光谱振幅和相位信息的高精度探测，以解决双光梳光谱测量精度受限于相位噪声和相对线宽的技术瓶颈。

光谱技术结合了光梳高频率精准、高频率分辨能力、高亮度的特点，为开展精密光谱快速分析提供了崭新的技术手段。但传统的控制精度和双光梳相对相位操控技术限制了双光梳光谱在精密测量方面的潜力。本项目以低噪声光梳的研制为基础，旨在进一步发展光学频率综合技术与前向反馈控制技术相结合的双光梳相对相位精密传递与操控技术，以超快光场精密操控技术解决双光梳光谱测量精度受限于相对线宽的技术瓶颈。项目开展了新型飞秒光梳相位噪声抑制技术的研究，发展了基于光纤飞秒激光器的超低相噪光梳；探索了双光梳相对相位精密控制的新方法，基于自参考主光梳结合两个连续激光器对实现了双光梳的频率同步，从光梳的内环频率不稳定度为1.18×10^-18，积分相位噪声为21.8mrad。实现了新型梳齿可分辨的高精度双光梳光学快速采样技术，完成了相干多外差光谱振幅和相位信息的高精度探测，下转换傅里叶光谱梳齿线宽小于1Hz。项目解决了相位噪声引起的光梳梳齿线宽加宽以及宽波段光梳相位信息高精度传递的关键科学问题，实现了双光梳相对相位精密操控的新方法。这一方法有望推动光梳光谱探测精度与分辨率的提升，为开展光谱精密测量的研究工作提供新的技术手段。