对基于非线性偏振旋转技术的L波段掺铒被动锁模光纤激光器中产生调Q锁模类噪声方波脉冲进行了实验研究。该类型脉冲中调Q包络内部包含的脉冲是基频方波, 通过自相关迹证实该方波为类噪声脉冲。为了容易实现类噪声方波脉冲输出, 将一段250 m普通单模光纤引进激光腔内。适当调节腔内的偏振控制器和泵浦功率, 获得了基频为778.21 kHz的连续波锁模类噪声方波脉冲和由3.81 kHz可调谐到9.01 kHz的重复频率, 单个调Q包络最高能量为1.06 μJ的调Q锁模类噪声方波脉冲。研究结果有利于进一步理解被动锁模光纤激光器中类噪声脉冲和调Q锁模的机理和特性。

The Q-switched mode-locking(QML) rectangular pulses in the L-band erbium-doped passively mode-locked fiber laser based on nonlinear polarization rotation technique was researched experimentally. The Q-switched envelope of this type of pulses contained the rectangular pulse with fundamental repetition rate, which was confirmed as noise-like pulse by an autocorrelator. A 250 m long section of single mode fiber was inserted into the cavity to ensure the noise-like rectangular pulses easy to be obtained. By carefully adjusting polarization controllers and pump power in the cavity, both the continuous-wave mode-locking noise-like rectangular pulses with fundamental repetition rate of 778.21 kHz and the QML noise-like rectangular pulses with tunable repetition rate from 3.81 kHz to 9.01 kHz and the highest energy of Q-switched pulse envelop 1.06 μJ were achieved. The research results further reveal the fundamental physics of noise-like pulses and QML operation in the passively mode-locked fiber lasers.广东省大学生创新创业训练计划(201611847093)