Generation of Sub-60 fs Similaritons at 1.6 μm From an All-Fiber Er-Doped Laser

We propose and demonstrate the generation of 1.6 μm similaritons in all-fiber lasers with two segments of different Er-doped fibers (EDFs), which can optimize the gain profile and the dispersion in the cavity. The fiber laser is mode-locked by nonlinear polarization rotation technology. The optimized EDF lengths force the laser operated at 1.6 μm, and the managed cavity dispersion is responsible for the similariton pulse generation. The laser delivers the chirped pulses with the duration of 2.4 ps. The pulses can be dechirped to 57.6 fs by using standard single-mode fibers outside the cavity. The output power is 47 mW and the repetition rate is 36 MHz, corresponding to the pulse energy of 1.3 nJ. The parabolic shape of the spectrum, the feature of the spectral width as a function of the pump power, and the pulse phase provide the evidence of the similariton generation. Furthermore, a simplified numerical model has been used to illustrate the main feature of our laser that can support amplifier similaritons. To the best of our knowledge, it is the first report that an ultrafast Er-doped all-fiber similariton laser operates at 1.6 μm with the pulse duration less than 60 fs.