A passively mode-locked thulium-doped fiber laser with square-wave pulse generation has been demonstrated using a figure-of-eight configuration with two gain mediums respectively located in the left and right loops. In this laser, mode-locking is achieved based on equivalent saturation absorption of a nonlinear amplifying loop mirror (NALM). The pulse amplitude and width of the square-wave pulse can be continuously extended through controlling pump power of gain mediums in the left and right loops. Moreover, the pulse dynamics and autocorrelation trace reveal the obtained square-wave pulse is a new kind of noise-like pulse, i.e., noise-like square-wave pulse, with capability of supporting higher pulse energy. This find enriches laser pulse dynamics and has important potential applications in laser detection, sensing and other fields.

中文翻译：

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脉冲持续时间和幅度可调的方波脉冲被动锁模掺铥光纤激光器


已经使用八字形配置演示了具有方波脉冲生成功能的被动锁模掺铥光纤激光器，其中两个增益介质分别位于左环和右环中。在该激光器中，锁模是基于非线性放大环镜（NALM）的等效饱和吸收来实现的。通过控制左右环路增益介质的泵浦功率，可以连续扩展方波脉冲的脉冲幅度和宽度。此外，脉冲动力学和自相关迹表明，所获得的方波脉冲是一种新型的类噪声脉冲，即类噪声方波脉冲，具有支持更高脉冲能量的能力。这一发现丰富了激光脉冲动力学，在激光探测、传感等领域具有重要的潜在应用。