Harmonic noise-like square pulse in an Er:Yb co-doped fiber laser at 1.61μm

The generation of high-power harmonic noise-like square pulses (NLSPs) is realized at 1.61 μm in an Er:Yb co-doped all-fiber mode-locked laser for the first time. By changing pump power and adjusting intra-cavity polarization state, the NLSP can operate in a fundamental or a high-order harmonic mode-locking (HML) state. The maximum average output power is about 1.26 W. To the best of our knowledge, this is the first demonstration of a watt-level harmonic NLSP.