Figure 1: Schematic of the laser and calculated pulse shapes.

(a) A short (2 m) conventional SMF part providing overdriving-free nonlinear-polarization-evolution (NPE) mode-locking and pulse amplification, and a long (40 m) polarization-maintaining fibre (PMF) part providing dissipative soliton (DS) formation. The Raman feedback loop provides dispersion-compensating delay for the RP directed into the bypass fibre by a wavelength-division multiplexer (WDM1) and its re-injection into the cavity (with coefficient R) via 1:R fibre splitter with output port D. The bypass piece of fibre between WDM1 and 1:R splitter for RP is 12 mm longer than the corresponding piece for DS. The active Yb³⁺-doped fibre is pumped by a laser diode via the WDM2 coupler. The polarization is controlled by a polarization controller (PC) and is split into orthogonal components by a polarization beam splitter (PBS) with the output port E. (b) The calculated shapes of the generated pulses in the corresponding points (A, B, C, D and E) of the laser scheme, without feedback and with feedback for the Stokes-shifted Raman pulse (RP).