We experimentally demonstrate a stable narrow-linewidth passively Q-switched fibre laser based on a microsphere resonator (MSR) and graphene saturable absorber (SA). The MSR made by the arc discharge method has the characteristics of easy fabrication, broad free spectral range (FSR) and flexibility. And it acts as a narrow band-pass filter to ensure narrow-linewidth operation. A stable passively Q-switched pulse with 0.016 nm narrow spectral linewidth is successfully achieved. The output pulse has the pulse width of 5.2 µs, repetition frequency of 28 kHz and high signal to noise ratio (SNR) of ∼60 dB. The results demonstrate that our works may provide an effective way to achieve narrow-linewidth pulsed fibre lasers.

中文翻译：

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基于微球谐振腔的窄线宽被动调Q光纤激光器

我们通过实验证明了一种基于微球谐振器 (MSR) 和石墨烯可饱和吸收器 (SA) 的稳定窄线宽被动调Q光纤激光器。电弧放电法制备的 MSR 具有制造容易、自由光谱范围宽、灵活性强等特点。它充当窄带通滤波器以确保窄线宽操作。成功实现了具有 0.016 nm 窄光谱线宽的稳定被动调Q脉冲。输出脉冲的脉冲宽度为 5.2 µs，重复频率为 28 kHz，信噪比 (SNR) 为~60 dB。结果表明，我们的工作可能为实现窄线宽脉冲光纤激光器提供了一种有效的方法。