基于高重复频率掺镱光纤光梳的相干拉曼光谱成像技术研究

激光光谱学和超快技术的发展极大地推动了物理学、化学和生物学等领域的研究进展，而基于双光梳测量的相干拉曼光谱成像方法就是一种最新发展起来的无标记光谱分析和成像方法，其具有信号强、方向性好、灵敏度高、探测效率高、光谱准确性高等优势，可以同时确定不同组成材料的拉曼光谱信息并进行成像。目前，此方法进行光谱分析和成像的核心技术指标- - -光谱分辨率和成像速率都取决于激光振荡器的重复频率。然而，目前为止，主要使用100MHz的钛宝石激光器，其限制了其光谱分析和成像的速度，同时两台价格高昂的钛宝石激光器也限制此类方法的进一步研究和推广。本课题计划利用课题组具有世界领先性的GHz高重频Yb光纤锁模激光器及特种光子晶体光纤的设计制作能力，能够得到高重频和宽带宽的光源。同时，配以高速的扫描振镜和高速探测器可以实现实时多光谱相干反斯托克斯拉曼光谱成像，会对物质成分和生物成像等研究提供极大的帮助。

Advances in laser spectroscopy and ultrafast technologies have had a profound impact throughout the physical, chemical and biological sciences. Coherent Raman spectroscopy based on dual laser frequency combs is a newly developing lable-free tool for the non-destructive and chemically selective probing of complex systems. It has advantages on robust signals, directionality, sensitivity, detection efficiency and spectrum accuracy. The imaging speed (refreshing time) is the inverse of the difference of the laser repetition frequencies. However, till now, only expensive Ti-sapphire mode-locked lasers with the repetition rate of 100MHz are used for these kinds of applications, while the expensive lasers also limit research development in these fileds. In this proposal, the leading-edge GHz repetition rate Yb:fiber mode-locked laser and laser frequency combs are used to replace the Ti-sapphire lasers. A broad pulse spectrum with high coherence and large mode space can be generated by special designed photonic crystal fiber can coherently broaden the pulse spectrum, making it an ideal high repetition rate imaging source with broad spectrum. Meanwhile, for microscopy experiments, scanning the laser beam with a galvanometric mirror and collecting signals with high-speed photodiode could even allow real-time hyper spectral dual-comb CARS imaging, benefiting the research of material composition and bio-imaging.