Fig. 1. Experimental setup of the NPR mode-locking Nd-doped single-mode all-fiber HML laser based on bending loss.

Fig. 2. (a) Simple experimental setup for measuring the emission spectrum of Nd-doped fiber after bending the SMF. (b) Emission spectra of the Nd-doped SMF after bending the SMF with different diameters.

Fig. 3. (a) Emission spectrum of the 12th HML laser over a wide range (860–1150 nm) with a resolution of 0.07 nm. The output characteristics of 0.9 µm Nd-doped all-fiber mode-locked laser operating at the fundamental frequency under the pump power of 136 mW. (b) Emission spectrum. (c) Pulse train. (d) Single-pulse shape. (e) The autocorrelation trace of the coherence spike and its sech² fitting within a narrower scan range. Inset: measured autocorrelation trace of the mode-locked pulse within a wider scan range.

Fig. 4. Evolutions of 0.9 µm Nd-doped all-fiber HML laser when the pump power changed from 88 to 391 mW. (a) Emission spectra. (b) Pulse trains. (c) Average output power and single-pulse energy.

Fig. 5. RF spectra of the 1st, 4th, 8th, and 12th HML laser within different bandwidths.