基于光梳的腔增强傅里叶变换光谱：在碰撞线形研究中的应用

本文在近红外区域构造了基于光学频率梳的腔增强傅里叶变换光谱仪，并用于Ar干扰的CO振转跃迁的谱线研究，高灵敏度的测量波数从6270 cm^-1到6410 cm^-1，涵盖CO第二泛频带的P和R分支. 该光谱仪提供的高分辨率超过了由干涉图长度确定的傅立叶变换分辨率极限，成功消除了线型函数的振铃和展宽效应. 本文可观察到Voigt线型曲线外的碰撞效应. 通过拟合速度依赖的Voigt曲线重新得到碰撞线型曲线参数，并与使用基于光学频率梳的高精密连续激光光腔衰荡光谱测量结果非常吻合.

Optical Frequency Comb-Based Cavity-Enhanced Fourier-Transform Spectroscopy: Application to Collisional Line-Shape Study

Direct-comb spectroscopy techniques uses optical frequency combs (OFCs) as spectroscopic light source. They deliver high sensitivity, high frequency resolution and precision in a broad spectral range. Due to these features, the field has burgeoned in recent years. In this work we constructed an OFC-based cavity-enhanced Fourier-transform spectrometer in the nearinfrared region and used it for a line-shape study of rovibrational transitions of CO perturbed by Ar. The highly sensitive measurements spanned the wavenumber range from 6270 cm^-1 to 6410 cm^-1, which covered both P and R branch of the second overtone band of CO. The spectrometer delivers high-resolution surpassing the Fourier-transform resolution limit determined by interferogram length, successfully removing ringing and broadening effects caused by instrumental line shape function. The instrumental-line-shape-free method and high signal-to-noise ratio in the measurement allowed us to observe collisional effects beyond those described by the Voigt profile. We retrieved collisional line-shape parameters by fitting the speed-dependent Voigt profile and found good agreement with the values given by precise cavity ring-down spectroscopy measurements that used a continuous-wave laser referenced to a stabilized OFC. The results demonstrate that OFC-based cavity-enhanced Fouriertransform spectroscopy is a strong tool for accurate line-shape studies that will be crucial for future spectral databases.