Nanojoule-energy-level, polarization-maintaining, dissipative-soliton mode-locked thulium fiber laser at 1876 nm

We report an environmentally robust, dissipative-soliton, mode-locked Tm-doped fiber laser operating in the short-wavelength infrared region at 1876 nm, using all-polarization-maintaining (all-PM) fibers. Self-starting, mode-locked operation is enabled by a single-wall carbon nanotube (SWNT) based saturable absorber (SA). Cavity dispersion is managed by using a commercially available PM dispersion compensating fiber (DCF). A PM fiber Lyot filter enables dissipative-soliton mode locking at a central wavelength of 1876 nm. The laser generates stable pulses at a repetition rate ∼ 19.2 MHz with an average power ∼ 21.5 mW, corresponding to a pulse energy ∼ 1.1 nJ. The output pulse has a duration of 4.2 ps and can be compressed down to 391 fs using a grating-based compressor. A higher pulse energy ∼ 3.2 nJ can be obtained with a compressed pulse width of 566 fs by varying the net cavity dispersion. To the best of our knowledge, this is the first nJ-energy-level, all-fiberized PM dissipative-soliton mode-locked Tm-doped fiber laser based on SWNT, with potential for applications in high-penetration nonlinear biomedical imaging microscopy.