Fiber-optic gyroscope is a new kind of inertial device.It has the highest theoretic sensitivity.But at present

its actual sensitivity is far less than the theoretic sensitivity.The main cause is:there are Rayleigh scattering

birefringence phenomenon and other nonlinear effects

such as Kerr effect

in optical fibers.They will cause nonreciprocal phase shifts of beams.This paper proposes to compensate such nonreciprocal phase errors by using photorefractive crystal

a new kind of nonlinear optical material

that is

using its thermal lens effect to weaken or eliminate the influence of Rayleigh scattering

using its bilateral phase effect to eliminate or correct the influence of birefringence phenomenon and Kerr effect

and then to improve the sensitivity of fiber-optic gyroscope.