Saturable absorber modelocked polarisation maintaining erbium-doped fibre laser

We passively modelock an erbium-doped fiber laser (EDFL) that generates 40pJ pulses 320fs wide and that operates in a single state of polarization (polarization extinction ratio better than 18dB). The self-starting of the laser is controlled by a semiconductor saturable absorber, and the fiber acts as the gain medium with some soliton pulse shaping. We squash the fiber preform to make the fiber polarization maintaining, and we design the core size and core-cladding index difference so the fiber is single mode and near the zero dispersion wavelength in the erbium-gain band.