title: Generation and evolution of mode-locked noise-like square-wave pulses in a large-anomalous-dispersion Er-doped ring fiber laser.
abstract: In a passively mode-locked Erbium-doped fiber laser with large anomalous-dispersion, we experimentally demonstrate the formation of noise-like square-wave pulse, which shows quite different features from conventional dissipative soliton resonance (DSR). The corresponding temporal and spectral characteristics of a variety of operation states, including Q-switched mode-locking, continuous-wave mode-locking and Raman-induced noise-like pulse near the lasing threshold, are also investigated. Stable noise-like square-wave mode-locked pulses can be obtained at a fundamental repetition frequency of 195 kHz, with pulse packet duration tunable from 15 ns to 306 ns and per-pulse energy up to 200 nJ. By reducing the linear cavity loss, stable higher-order harmonic mode-locking had also been observed, with pulse duration ranging from 37 ns at the 21st order harmonic wave to 320 ns at the fundamental order. After propagating along a piece of long telecom fiber, the generated square-wave pulses do not show any obvious change, indicating that the generated noise-like square-wave pulse can be considered as high-energy pulse packet for some promising applications. These experimental results should shed some light on the further understanding of the mechanism and characteristics of noise-like square-wave pulses.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.forename: Pinghua
authors.initials: P
authors.lastname: Tang
authors.forename: Changwen
authors.initials: C
authors.lastname: Xu
authors.forename: Chujun
authors.initials: C
authors.lastname: Zhao
authors.forename: Han
authors.initials: H
authors.lastname: Zhang
authors.forename: Shuangchun
authors.initials: S
authors.lastname: Wen