Optimizing polarization states in a figure-8 laser using a nonreciprocal phase shifter

The polarization states in a figure and laser are analyzed using Jones matrices. The analysis shows that a figure-8 laser in CW operation does not give enough information to allow the optimization of the birefringence for mode-locking. A switchable nonreciprocal phase shifter is proposed to provide a simple way to optimize the birefringence for a mode-locked figure-8 laser. Using this device, the mode-locking of a diode-pumped figure-8 laser was started, with a probability better than 99%, by following a sequence of predetermined mechanical adjustment. With the proposed nonreciprocal phase shifter, the optimization and starting of a figure-8 laser can easily be automated