Abstract
A polarization model for calculating the ellipticities of the clockwise and counterclockwise
output beams in square ring resonators is established in this article. The model takes into account the
following parameters such as Ar, g, ξ and Φ simultaneously, where Ar is the distortion angle, g is the
phase shift of all four mirrors, ξ is the angle between the S-polarization and the substrate "fast" axis of
the output mirror, Φ is the birefringence angle of the output mirror. With the consideration of the
output mirror's stress effect, the parameters such as ξ and Φ have unsymmetrical influences on the
ellipticities of clockwise and counterclockwise beams, and the distortion angle is unequal to zero when
the ellipticities of clockwise and counterclockwise output beams are equivalent. Based on those novel
results, A novel method to controll the distortion angle during the alignment process with the
eliminatation of the output mirror's stress effect simultaneously has been proposed in this article and
this method can decrease the magnetic bias of square ring resonators effectively. These interesting
findings are important to the research of high precision and super high precision ring laser gyros.
