Polarization properties and frequency stabilization of an internal-mirror 1523 nm He-Ne laser under axial magnetic field

The polarization properties of an internal-mirror 1523 nm He-Ne laser under an axial magnetic field were investigated. When the axial magnetic field w as around 12 mT, the laser operated in single mode with two opposite circul arly polarized components near the center of gain profile. In addition, due to the competition between these two opposite circularly polarized compone nts, each mode had only one circularly polarized component survived when th e laser operated in the two-mode region. We could stabilize the laser frequ ency at either the center of gain profile or the symmetric two-mode taking advantage of the power difference between the two circularly polarized comp onents of the laser output, and the stability achieved was better than 1 MH z.