OPTIMIZATION POLARIZATION STATES IN A FIGURE-8 LASER USING A NONRECIPROCAL PHASE-SHIFTER

The polarization states in a figure 8-laser are analyzed using Jones m atrices. The analysis shows that a figure-8 laser in CW operation does not give enough information to allow the optimization of the birefrin gence for mode-locking. A switchable nonreciprocal phase shifter is pr oposed to provide a simple way to optimize the birefringence for a mod e-locked figure-8 laser. Using this device, the mode-locking of a diod e-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 starti ng of a figure-8 laser can easily be automated.