Bidirectional operation and gyroscopic properties of passively mode-locked Nd:YVO4 ring laser

A simple ED-end-pumped passively mode-locked NdYVO4 ring laser with bidirectional outputs was demonstrated and the gyroscopic properties of the ring laser was studied. The laser was continuous wave mode locked by use of a semiconductor saturable absorber mirror (SESAM) and both clockwise and counter clockwise outputs are stable laser pulse trains with pulse duration of 64 ps. The continuous wave mode locking was obtained under pump power as low as 540 mW. The average output power is 50 mW for the counter clockwise laser and 52 mW for the clockwise laser under pump power of 1378 mW. The whole slope efficiency of the ring laser is about 9.4%. The two output pulse trans of the ring laser were combined to study its gyroscopic properties. The beat frequency of the pulsed solid-state laser gyro versus the rotation rates follows the Sagnac formula. The laser gyro has a large dead band of 6-8 dec/s which was believed to be caused by the long pulse duration and the colliding of the opposite pulses on the SESAM.