为深入分析双纵模稳频氦氖激光器的稳频机理和精度误差,本文提出了双纵模产生的必要条件:内腔型激光器和谐振腔长在100～300mm之间。按照激光器的工作过程,稳频分为三个阶段:跳模、过渡阶段,模式稳定。结合激光原理和热力学理论,根据光电探测器的电压变化,阐述了稳频机理。拍频实验结果表明,激光器的频率稳定度高达5×10^-10。通过误差分析,确定稳频精度仅取决于腔长的变化量,且增加腔长,有助于增加频率稳定度。该方法锁定时间短。

In order to analyze working principle and stability error of double longitudinal-mode He-Ne laser with stabilization frequency,a requirement is put forward,which is that an intracavity laser with cavity of 100～300 mm length can produce double longitudinal-mode light.According to laser working process,stabilization frequency includes mode hopping,transition stage and stabilized mode.With laser principle and thermodynamic theory,mechanism of stabilization frequency of the laser is interpreted on the basis of output voltages of the two photodiodes.Beat frequency test shows that frequency stability of He-Ne laser is 5×10^-10.Based on error analysis,the frequency stability of He-Ne laser is only influenced by change of resonant cavity length.Furthermore,increasing length of the resonant cavity can lead to higher frequency stability.The laser with double longitudinal-mode stabilized frequency has a shorter locked time.