Sub-100 fs All-Fiber Polarisation Maintaining Tunable Laser from ~1870 nm up to ~2050 nm

Mode-locked oscillators at $2\ \mu\mathrm{m}$ wavelength usually rely on saturable absorbers, non-linear polarisation rotation or SESAMs producing either pulses in the pJ range or pulses with higher energies that require further pulse compression outside of the cavity. They are based on Tm-doped, Ho-doped or Tm-Ho-codoped materials to provide different discrete emission wavelengths. An alternative to generate continuously tunable femtosecond (fs) pulses rely on Raman scattering through Soliton Self-Frequency Shift (SSFS) delivering Fourier transformed pulses. The energy and pulse duration of the solitons are well defined and are strongly dependent on the fiber characteristics such as dispersion and the non-linear coefficient. That is why a large amount of work has been done on producing custom optical fibers such as photonic crystal fibers [1], tellurite fibers [2] and dispersion managed fibers with tailored properties to further control the resulting soliton pulses.