Polarization maintaining, normal-dispersion silica fiber for dispersion compensation in ultrafast erbium and thulium-doped fiber lasers

We present a highly birefringent silica fiber with normal dispersion up to 2334 nm, designed to control a net-cavity dispersion of pulsed fiber lasers at different wavelengths. The fiber is characterized by a large normal dispersion, slowly growing from -87 ps/nm/km at 1200 nm to -42 ps/nm/km at 2000nm, and high phase birefringence exceeding 1.9 × 10^-4 in this spectral range which ensures a polarization extinction ratio as high as 28 dB for a 1 m long fiber section. The industrially fabricated fiber was examined in two all-polarization-maintaining mode-locked fiber oscillators operating at central wavelengths of 1560 nm and 1980nm. We confirmed the ability to manage the dispersion of the oscillators, which worked in both anomalous and normal dispersion, maintaining stable mode-locking. Employing the developed fiber with normal dispersion has resulted in a broadening of spectral full width at half maximum from 7.8 to 44.3 nm and from 5.5 to 25.8 nm for the erbium and thulium lasers, respectively. The ability to support operation in the range of tens of MHz allows for the application of the developed laser sources in systems reducing the repetition rate via e.g. pulse picking.