Polynomial model of the frequency characteristic of a slowly rotating vibrating laser gyro with differently amplified counterpropagating waves

Expressions are obtained for calculating the four first coefficients of a polynomial model of the frequency characteristic of a slowly rotating laser gyro on a vibration stage. The expressions are valid when the gyro operates at the gain line centre and currents in its arms are balanced, however, the amplifications of counterpropagating waves are slightly different due to slightly different Q factors of the resonator for these waves. Analysis of the expressions suggests that the difference in the amplification of counterpropagating waves of the laser gyro leads to the zero shift and produces the component of the output signal that does not commute with the angular velocity.