The frequency split phenomenon in a HeNe laser with a rotational quartz plate in its cavity

Abstract

Theory and experiments indicate that the output of a HeNe laser containing an intracavity rotational quartz plate will split into two perpendicularly polarized modes. The frequency difference between the two modes varies periodically with the quartz plate's rotation over a range of one longitudinal mode separation. We have found that the amplitude of the gain curve is reduced as the mode split happens.