搭建了一套迈克尔逊干涉仪, 对CO2激光的9P36和9R10谱线泵浦CH3OH气体所产生的频率分别为2.52 THz和3.11 THz的太赫兹激光器输出频谱进行了精细测量。测量系统频率分辨率约为1 GHz, 测量结果显示CO2激光泵浦的太赫兹源为单色源并具有极窄的线宽, 波长与激光器标称值进行对比具有很好的一致性。基于这套系统实现了对干涉仪动臂目标的运动速度准确测量, 提出了两种分别适用于匀速运动和变速运动情况下的速度反演方法, 反演结果与设定值均相符。结论表明, 迈克尔逊干涉仪不但可以精确测量太赫兹波源的频谱, 同时配合单色太赫兹源可以准确测量目标速度, 为太赫兹波段光谱、成像等领域的应用奠定基础。

A Michelson interferometer was constructed to measure the spectra generated by a terahertz (THz) gas laser pumped by a CO2 laser. The hyperfine spectra at 2.52 THz and 3.11 THz generated in CH3OH gas pumped by the 9P36 and 9R10 laser lines of the CO2 laser was measured with the frequency resolution of around 1 GHz. The measurement results showed that the THz laser was monochromatic and had very narrow linewidth. The measured wavelength was consistent with the nominal value. Velocity measurement of target on the translation mirror was also performed based on this interferometer. Two methods for acquiring velocity were proposed, demonstrating good accordance with the set values for both fixed and variable velocities. It is concluded that the Michelson interferometer could be used to accurately measure the spectrum of a THz source, and the velocity measurement was also possible with the help of a monochromatic THz source, laying the basis for THz applications like spectroscopy, imaging, etc.