We demonstrated a passively mode-locked fiber laser operating at 1982 nm by using a gold nanorods (GNRs) saturable absorber (SA). The GNRs SA was fabricated by mixing GNRs with sodium carbonxymethyl cellulose. By inserting the GNRs SA into a Tm-doped fiber laser cavity pumped by a 1570 nm fiber laser, stable passively mode-locking was achieved with a threshold pump power of 224 mW, ~4.02 ps pulses at 1982 nm with a repetition rate of ~37.49 MHz, and a maximum average power of ~6 mW was obtained for a pump power of ~265 mW.

We demonstrated a widely tunable mode-locked thulium doped fiber laser (TDFL) by using a homemade multimode interference filter (MMIF). The MMIF had a structure of single mode fiber (SMF)—multimode fiber (MMF)—SMF and three main transmission peaks at 1901.2, 1957.2 and 2043.2 nm. By mechanically bending the MMIF, the three main transmission peaks were tuned in the range of 1860–2024 nm due to multimode interference effect. By inserting the MMIF into a passively mode-locked TDFL cavity pumped by a 1570 nm fiber laser, a tunable mode-locked TDFL with a tuning range of 1919.6–2014.9 nm was achieved by adjusting the MMIF. To the best of our knowledge, such a tunable range is the largest among all-fiber tunable mode-locked TDFLs.