频率调制光谱(FMS)技术不仅可以用来同时测量原子和分子的吸收和色散, 还是噪声免疫腔增强光外差分子光谱（NICE-OHMS）的关键技术, 由于光纤器件的引入或光源输出光的偏振态不稳定等因素会诱发残余幅度调制(RAM), RAM的产生使得FMS技术在痕量气体检测中的应用受到极大的限制, 因此研究光纤FMS中RAM的特性具有非常重要的意义。 研究首先通过理论分析了无吸收时的FMS信号的线型及RAM的影响因素, 实验测量无吸收时输入偏振方向和输出偏振方向及电光调制器(EOM)温度对光纤FMS中RAM的影响, 均与RAM存在线型关系, 验证了理论分析结果, 并为RAM的抑制工作以及基于RAM的其他应用提供了依据。

Frequency modulation spectroscopy (FMS) not only can be used to simultaneously measure the absorption and dispersion of atoms and molecules, but is the key technology of the noise immunity cavity enhanced optical heterodyne molecular spectroscopy(NICE-OHMS). The optical devices or the instability of output light polarization of the laser source will induce the residual amplitude modulation (RAM) in the FMS. RAM greatly limits the FMS technology application in trace gas detection, so the research on the RAM characteristics in the FMS has very important significance. Firstly, the lineshape of FMS without absorption was analyzed, and the impact factors on the RAM were acquired, then the influence of input and output polarization direction and electro-optical modulation (EOM) temperature was measured, respectively. They all have linear relationship with the RAM. The results verify the theoretical analysis and provide the basis for reducing the RAM and other related working.