Developing novel materials with excellent nonlinear optical response and ultrafast carrier dynamics is of great significance for the development of optoelectronic devices. In this contribution, amorphous Fe-doped ZIF-67 (Fe-ZIF-67) was successfully synthesized and characterized in detail. Femtosecond-resolved transient absorption spectroscopy (TAS) clearly revealed the ultrafast carrier dynamics of Fe-ZIF-67 and ZIF-67. The results showed that amorphous Fe-ZIF-67 exhibited a deeper photoinduced bleaching valley and a higher photoinduced absorption peak when compared with the crystalline ZIF-67. Meanwhile, the introduction of Fe ions promoted the charge transfer in ZIF-67 and significantly inhibited the photogenerated carrier recombination, thus greatly enhancing the nonlinear optical response of Fe-ZIF-67. This indicates its great potential in nonlinear optical applications. In addition, amorphous Fe-ZIF-67 displayed excellent nonlinear saturation absorption features at 1.5 μm, with a modulation depth of 3.1% and a saturation light intensity of 1.84 MW cm⁻². Subsequently, Fe-ZIF-67 was inserted into an erbium-doped fiber ring cavity to generate conventional soliton mode-locking laser pulses with a pulse width of 1.23 ps and a wavelength of 1560.8 nm. Surprisingly, the harmonic order of mode locking could be tuned by adjusting the polarization controller (PC), which is different from the previously known method of adjusting the pump power. Finally, a 95th-order harmonic mode-locking pulse output was obtained with a repetition rate of 694.8 MHz. Compared to the crystalline ZIF-67 saturable absorber (SA), amorphous Fe-ZIF-67 SA increased the mode-locking frequency to the order of several hundred megahertz. Therefore, it is of great significance to synthesize amorphous advanced MOF functional materials by changing the crystal structure through doping and to further investigate their feasibility for application in the field of optoelectronics.

中文翻译：

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非晶 Fe 掺杂 ZIF-67 中增强的非线性光学响应和超快载流子动力学

开发具有优异非线性光学响应和超快载流子动力学的新型材料对于光电器件的发展具有重要意义。在这篇文章中，成功合成了非晶铁掺杂 ZIF-67 (Fe-ZIF-67)，并对其进行了详细表征。飞秒分辨瞬态吸收光谱（TAS）清楚地揭示了 Fe-ZIF-67 和 ZIF-67 的超快载流子动力学。结果表明，与晶态ZIF-67相比，非晶态Fe-ZIF-67表现出更深的光致漂白谷和更高的光致吸收峰。同时，Fe离子的引入促进了ZIF-67中的电荷转移并显着抑制了光生载流子复合，从而大大增强了Fe-ZIF-67的非线性光学响应。这表明其在非线性光学应用中的巨大潜力。此外，非晶态Fe-ZIF-67在1.5 μm处表现出优异的非线性饱和吸收特性，调制深度为3.1%，饱和光强度为1.84 MW cm ^-2。随后，将Fe-ZIF-67插入掺铒光纤环形腔中，产生脉冲宽度为1.23 ps、波长为1560.8 nm的常规孤子锁模激光脉冲。令人惊讶的是，锁模的谐波阶次可以通过调节偏振控制器（PC）来调节，这与之前已知的调节泵浦功率的方法不同。最终获得重复率为694.8 MHz的95次谐波锁模脉冲输出。与结晶ZIF-67可饱和吸收体（SA）相比，非晶Fe-ZIF-67 SA将锁模频率提高到数百兆赫兹的数量级。因此，通过掺杂改变晶体结构来合成非晶先进MOF功能材料并进一步研究其在光电子领域应用的可行性具有重要意义。