电光调制器输入端光纤温度对光纤频率调制光谱影响的研究

激光光谱技术由于其高灵敏、高分辨、可在线检测等优点被广泛的应用与痕量气体探测领域，而频率调制光谱(FMS)技术由于其除了探测灵敏度高的优点外且可同时探测气体样品的吸收和色散，通常还被应用于原子分子物理、量子光学等领域。发展全光纤FMS可以在保持气体探测灵敏度的同时有效简化实验装置，然而FMS是一项偏振态敏感技术，光纤温度变化等引起不适当的偏振态变化会诱发残余幅度调制(RAM)，该RAM不仅使FMS线型扭曲，同时对其色散信号产生直流偏置，因此研究光纤温度对RAM特性的影响具有非常重要的意义。研究首先通过理论和实验验证了相位可控波片模型解释保偏光纤特性的可行性，然后实验测量了进入电光调制器(EOM)前保偏光纤温度对RAM的影响，发现由RAM引起的色散光谱直流偏置随温度呈正弦变化，且在24和26.8 ℃时直流偏置为零，即无RAM的状态，然而基于温度的直接RAM消除无法替代Wong-Hall提出的伺服反馈控制来实现其长期抑制，这种温度诱发RAM的变化也是所有FMS色散信号背景漂移的主要原因。

Theoretical Analysis of the Residual Amplitude Modulation of Frequency Modulation Strong Absorption Spectroscopy

In the present paper a phase controllable waveplate model was applied to the analysis of polarization maintaining fiber. Under the temperatures of 24 ℃ and 26.8 ℃ there is no residual amplitude modulation (RAM) existing in frequency modulation spectroscopy (FMS) when performing the measurement of fiber temperature dependence on the RAM. However, the temperature setting can not reduce the background long term drift and a servo feedback suggested by N. C. Wong and J. L. Hall can be used to actively reduce the RAM. The error signal for feedback is from the dispersion background signal of FMS without gas sample. The variation of RAM induced by the temperature changing of PM fiber is the main reason for the long term background drift of dispersion signal of FMS.