Magnetooptic mode splitting in an anisotropic laser cavity

The normal modes of an anisotropic laser resonator containing an intracavity Faraday rotator have been investigated. Below a threshold value of rotation, the Faraday cell rotates the electric field vector of the linearly polarized modes. Above this value, each axial mode splits into two elliptically polarized waves. The frequency difference of these modes is then dependent on the Faraday rotation angle. Experimental results obtained using a 3.39-μ He-Ne laser with two Brewster windows and a YIG intracavity Faraday cell are in agreement with the results calculated from a normal mode analysis.