In this paper, we experimentally demonstrate generation of diverse structures of robust optical pulses obtained with a ring cavity passively mode-locked fiber laser based on a double-clad erbium-ytterbium doped fiber, and operating at net-anomalous cavity dispersion. A half-wave and a quarter-wave retarder plates allow adjustable saturable absorbing action by the nonlinear polarization rotation technique. Pulsed laser operation in quasi- continuous wave, molecules of solitons, and single-wavelength noise-like pulses (NLPs) regimes is obtained by properly adjusting the wave retarders. In the soliton and NLPs operating regimes, the central laser wavelength lies in the 1540 nm region. The obtained NLPs exhibit narrow peak coherence of ∼231 fs.

We present a simple and efficient experimental approach to synchronized dual-wavelength pulsed operation in an all-fiber laser. Four different dual-wavelength emissions of synchronized picosecond pulses are generated through simple adjustments of a wave retarder. Autocorrelation traces exhibit modulation profiles corresponding to dual-wavelength emissions with wavelength separations ranging over one order of magnitude, from 0.96 to 9 nm. In all cases, it is observed stable dual-wavelength operation and perfect synchronization between both pulsed components, without requiring of intra-cavity dispersion management. For the first time, to the best of our knowledge, synchronous tunable dual-wavelength pulse emission in a single-cavity Er/Yb double clad ring fiber laser is experimentally demonstrated.

We report an experimental study of switchable rectangular pulses generation in a passively mode-locked double-clad thulium-doped fiber laser operating in the anomalous dispersion regime. A fiber loop mirror and a polarization imbalanced nonlinear optical loop mirror (NOLM) forms the linear cavity. The loop in the NOLM includes a quarter-wave retarder, which allows switching between two regimes of rectangular pulse generation. The laser generates rectangular noise-like pulses (NLPs) or dissipative soliton resonance (DSR) pulses with 1.18 MHz repetition rate at ∼1990 nm. At the maximum pump power of 10 W, rectangular pulses with energy of up to 540 nJ in DSR operation and 482 nJ in NLP operation were obtained with output average power of 640 mW and 571 mW, respectively.