Stabilization of pulsed lightwave circulating around an amplified fiber-optic ring incorporating a Lyot depolarizer

We describe an effective method for stabilizing a pulsed lightwave circulating around an amplified fiber-optic ring containing an acoustooptic frequency shifter. By installing a Lyot depolarizer with a large birefringence in the ring, we can effectively suppress the change in the maximum number of the pulse circulations caused by a fluctuation in the ring birefringence. We experimentally confirmed that the change in the number of circulations was suppressed to less than 30, which is very small compared with the maximum number of pulse circulations of 730.