  We theoretically and numerically study the effect of backscattering on
rotating ring lasers by employing the Maxwell-Bloch equations. We show that
frequency shifts due to the Sagnac effect incorporating the effect of
backscattering can be observed without lock-in phenomenon, if the strength of
backscattering originating in the bumps of the refractive index is larger than
a certain value. It is also shown that the experimental results corresponding
to the theoretical ones can actually be obtained by using a semiconductor
fiber-optic ring laser gyroscope.
