We experimentally demonstrated an all-fiber mode-locked erbium-doped laser based on Co²⁺:ZnSe (Cobalt, Zinc Selenide) thin film as the saturable absorber (SA), which was grown on the fiber taper by electron beam (e-beam) evaporation technology. The modulation depth, non-saturable loss and saturation intensity were found to be ∼12%, 76% and 1.89 MW/cm², respectively. The X ray diffraction (XRD) results showed that the Co²⁺:ZnSe thin film was provided with the cubic zinc blende structure. The scanning electron microscope (SEM) and atomic force microscopy (AFM) images showed the prepared thin film has a smooth and uniform surface. When the fiber-taper Co²⁺:ZnSe SA was inserted into an erbium-doped fiber laser cavity, a stable mode-locked pulse was obtained. The mode-locked pulses had a pulse repetition rate of 17.83 MHz and pulse duration of ∼4 ns throughout the mode-locked operation range of 200-600 mW. The recorded maximum average output power was ∼4.88 mW. The signal to noise ratio (SNR) was obtained to be 64.9 dB, which indicates the favorable stability of the mode-locked pulse. These results demonstrate the Co²⁺:ZnSe thin film grown on a fiber taper has high optical quality and implementation of stable pulse operation on passively mode-locked Er-doped fiber lasers.

中文翻译：

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基于电子束蒸发生长的 Co ²⁺ :ZnSe 薄膜可饱和吸收体的全光纤被动锁模激光器

我们通过实验证明了一种基于 Co ²⁺ :ZnSe（钴、硒化锌）薄膜作为可饱和吸收体 (SA)的全光纤锁模掺铒激光器，该激光器通过电子束在光纤锥形上生长 (e-束）蒸发技术。调制深度、非饱和损耗和饱和强度分别为~12%、76% 和1.89 MW/cm ²。X射线衍射(XRD)结果表明Co ²⁺ :ZnSe薄膜具有立方闪锌矿结构。扫描电子显微镜 (SEM) 和原子力显微镜 (AFM) 图像显示制备的薄膜具有光滑均匀的表面。当纤维锥度 Co ²⁺:ZnSe SA 插入掺铒光纤激光器腔内，得到稳定的锁模脉冲。在整个 200-600 mW 的锁模操作范围内，锁模脉冲的脉冲重复率为 17.83 MHz，脉冲持续时间约为 4 ns。记录的最大平均输出功率约为 4.88 mW。获得的信噪比 (SNR) 为 64.9 dB，这表明锁模脉冲具有良好的稳定性。这些结果表明，在光纤锥形上生长的 Co ²⁺ :ZnSe 薄膜具有高光学质量，并且在被动锁模掺铒光纤激光器上实现了稳定的脉冲操作。