Polarization Anisotropy in HeNe Zeeman Lasers with Internal Mirrors

实验测量了633nm内反射镜激光器在轴向磁场下几乎工作一模和两模的输出功率和塞曼拍频随腔失谐的变化规律。在塞曼热出现之前的磁场强度下，激光管的偏振取决于相邻两个纵向模式增益的空间分布和腔镜各向异性效应之间的竞争。在激光介质的塞曼效应、同位素效应和腔镜各向异性效应的平衡点决定了出现塞曼振荡频率的最小磁场强度Hc。在横向磁场中，激光管的塞曼节拍频率和沿自然轴的极化输出功率作为腔失谐的函数是不同的，并且取决于磁场强度和自然轴磁场方向。塞曼拍频特性是由相位各向异性和损耗各向异性引起的频率差决定的。

The output power and the Zeeman beat frequency as a function of the cavity detuning are measured in experiments for 633nm HeNe lasers with internal mirrors which operate almost one and two modes in the axial magnetic fields. At a magnetic strength before Zeeman beat appears, a polarization of a laser tube depends on the competition between the spatial distribution of the gain of two adjacent longitudinal modes and the effect of anisotropy of cavity mirrors. The minimum magnetic strength Hc at which a Zeeman beat frequency appears is decided at the point in the balance of Zeeman effect of the lasing medium, the isotope effect and the effect of the anisotropy of cavity mirrors. In transverse magnetic fields, Zeeman beat frequency and the polarized output powers along the natural axes as a function of the cavity detuning are different for laser tubes and depend on the strength of the magnetic field and the direction of the magnetic field for the natural axis. The properties of Zeeman beat frequency is decided as the frequency differences caused by the phase- and loss-anisotropy.