All Polarization-maintaining Passively Mode-locked Ytterbium-doped Fiber Lasers, Behavior under Two Different Cavity Configurations

In this work, we review our recent investigations on the behavior of a polarization-maintaining passively mode-locked ytterbium-doped laser in two different cavity configurations, namely: fiber-ring (FR) and Fabry-Perot (FP). Opposed to standard configurations that rely on the use of strong filtering within the cavity by including an ad hoc component with this purpose, here the filtering action is solely performed by the spectral overlapping of the different components within the fiber lasers. We found that the lack of a specific filter within the cavity does not deteriorate the performance as compared with previous works. We also report the changes in the output light pulses when the net dispersion of the cavity was varied. Additionally, different lengths of an ad hoc anomalous polarization-maintaining (PM) photonic crystal fiber (PCF) were used as intracavity dispersion compensator, to shift the operation of the laser from net-normal to the net-anomalous regime. The shortest output light pulses [6 ps (FR) and 8 ps (FP)] were obtained when the net-cavity dispersion approached zero. Since the obtained light pulses were far to be transform-limited, we also discuss the possibility of out-of-cavity recompression by using the same PM-PCF mentioned above. After recompression, pulse widths of 3 ps were obtained, limited by the available length of PM PCF