Bow-tie cavity ringdown spectroscopy for observing a circular dichroism of gas-phase molecules

我们尝试研制了一种全新的光腔衰荡光谱仪，它是由一个蝴蝶结光学腔构成的。我们的研究目标是实现气相分子的圆二色性（CD）的高灵敏度检测。在第一年，我们研究了利用脉冲OPO激光系统测量光腔衰荡。然而，我们了解到，与连续波（CW）激光器相结合的腔增强吸收光谱技术比脉冲衰荡技术具有更高的灵敏度。因此，我们在第二年改变了CD测量的光谱技术。研究了可见光区连续激光器的性能，优化了双高反镜光学腔的结构，发展了腔外透射光的检测技术。这些基础实验将在我们今后研究气相分子的CD测量中发挥作用。

We tried to develop a brand-new cavity ringdown spectrometer, which is constructed by a bow-tie optical cavity. Our research goal is to achieve highly sensitive detection of a circular dichroism (CD) for the gas-phase molecule. In the 1st year, we studied the cavity ringdown measurement using a pulsed OPO laser system. However, we learned that a cavity enhanced absorption spectroscopy, which is combined with a continuous-wave (CW) laser, has substantially higher sensitivity than a pulsed ringdown technique. As a result, we have changed a spectroscopic technique for CD measurement in the 2nd year. We have examined a performance of the visible region CW laser, optimized the configuration of an optical cavity by two high reflective mirrors, and developed the detection technique of a transmitted light out of a cavity. These fundamental experiments will play roles in our future study of the CD measurement of gas-phase molecules.