报告题目：Sub-kHz level mid-infrared saturation spectroscopy of complex molecules and its applications to fundamental physics
报告人：刘禹昊 博士
报告人单位：Laboratoire de Physique des Lasers, Sorbonne Paris North University
主持人：瞿岸 研究员
报告时间：2024年8月6日（周二）上午10:00
报告地点：光学大楼B225会议室
报告内容：
Molecular systems, owing to their numerous degrees of freedom, offer promising perspectives for improving spectroscopic tests of fundamental physics and precision measurements in general [1,2]. Ultra-stable lasers are required for precision spectroscopic measurements. Using a near infrared optical frequency comb, we stabilized a 10 μm quantum cascade laser (QCL) to an ultra-stable near infrared reference signal operated at the French metrology institute via a fiber cable of the REFIMEVE infrastructure [3]. This results in a record relative frequency uncertainty of 10−14 and a 0.1 Hz QCL linewidth [4].
We have used this laser to perform high resolution spectroscopy on various molecular species of fundamental, atmospheric and astrophysics interest, by realizing cavity enhanced saturated absorption measurements. I will show results on osmium tetroxide, methanol and ethylene achieving a few hundred hertz uncertainties on molecular frequencies and present investigations of various noise sources currently limiting our signal-to-noise ratio as well as perspectives for improvements.
These results enhance our ability to meet the needs for our ongoing efforts towards studying the variation of fundamental constants[2] or testing fundamental symmetries, e.g. by measuring the tiny parity-violating energy difference between enantiomers of a chiral molecule[1]. Furthermore, it can contribute to the enrichment and refinement of the HITRAN database, which can be highly beneficial for the fields of astronomy and atmospheric physics, providing valuable data for accurate modeling and analysis.
References:
[1] A. Cournol et al., Quantum Electronics 49, 288 (2019)
[2] J. Bagdonaite et al., Science 339,46 (2013)
[3] www.refimeve.fr
[4] Tran et al., APL Photon. 9, 030801 (2024)
报告人简介：
Liu Yuhao is currently a Ph.D. student in Benoit Darquié's group at the Laboratoire de Physique des Lasers, Sorbonne Paris North University. He earned his Bachelor's degree from Wuhan University and Lyon 1 University in 2018, and subsequently obtained his Master's degree in the Interaction of Light and Matter from Sorbonne University in 2020. His current research interests include metrology and the measurement of fundamental constants. During his doctoral studies, he has been engaged in cavity-enhanced high-resolution molecular spectroscopy and sub-Hertz linewidth mid-infrared laser stabilization using optical frequency comb, as well as their applications in investigating the temporal and spatial variations of fundamental constants.