Generation of Q-switched mode-locking noise-like pulses based on nonlinear polarization rotation in a thulium-doped all-fiber laser

Abstract

In this work a Q-switched mode-locked (QML) noise-like pulse (NLP) emission from a thulium-doped all-fiber laser with passive saturable absorption action through the nonlinear polarization rotation effect is demonstrated. QML-NLP pulses were obtained at 812 kHz repetition rate within a 11 μs QML envelope and pulse energy of 460 nJ. Central modelocked NLP sub-pulses were measured with 8.71 ns of width and 4.17 of peak power. The evolution of QML-NLP is experimentally investigated, and the results demonstrate the feasibility of an unconventional pulse operation regime of NLPs and provide insights into the dynamics of mode-locked fiber lasers.