We consider a ring resonator filled with a nonlinear medium which is pumped by a pair of counter-propagating laser beams with the same frequency. As a result of optical four-wave mixing, transmission "gains" are available for the oppositely directed traveling waves sup-ported by the resonator. Thus, oscillation will result provided the coupling is strong enough to overcome the mirror loss. Since the two lasing modes are coherently coupled via four-wave mixing, they are mutually phase conjugated and are invulnerable to frequency pulling due to backscattering. Thus, such a gyro will have a reduced lock-in effect. We will present this new concept as well as the result of our analysis.
"Phase Conjugate Ring Gyroscopes", Proc. SPIE 0412, Fiber Optic and Laser Sensors I, (19 September 1983); doi: 10.1117/12.935822; https://doi.org/10.1117/12.935822