Pulse-energy-scaling of a Tm$^{3+}$-based 3×3-coupler NALM at 2000 nm

We report the first noise-like mode-locked (NLML), high-pulse-energy, low-repetition-rate Tm$^{3+}$-doped fiber laser based on a 3×3-coupler nonlinear amplifying loop mirror (NALM) at 2 µm. The effect of cavity length changes on energy scaling is investigated in an all-fiber, all-polarization-maintaining configuration, yielding 2 ns pulses with energies up to 33 nJ. In addition, the laser exhibits harmonic noise-like mode-locking (HNLML) and broadband supercontinuum generation spanning 1.95 to 2.25 µm at elevated pump powers.