Liu Jun, Chen Yu, Tang Pinghua, Xu Changwen, Zhao Chujun, Zhang Han, Wen Shuangchun
Opt Express. 2015 Mar 9;23(5):6418-27. doi: 10.1364/OE.23.006418.
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.
在一个具有大反常色散的被动锁模掺铒光纤激光器中，我们通过实验证明了类噪声方波脉冲的形成，其表现出与传统耗散孤子共振（DSR）截然不同的特性。我们还研究了包括调Q锁模、连续波锁模以及在激光阈值附近拉曼诱导的类噪声脉冲在内的各种工作状态下相应的时域和频域特性。在195kHz的基频重复频率下可获得稳定的类噪声方波锁模脉冲，脉冲包持续时间可在15ns至306ns范围内调谐，单脉冲能量高达200nJ。通过降低线性腔损耗，还观察到了稳定的高阶谐波锁模，脉冲持续时间从21阶谐波处的37ns到基频处的320ns不等。在沿一段长的通信光纤传输后，所产生的方波脉冲没有显示出任何明显变化，这表明所产生的类噪声方波脉冲可被视为适用于某些有前景应用的高能量脉冲包。这些实验结果将有助于进一步理解类噪声方波脉冲的机制和特性。
