By employing different flow rates (0.1 mL/h, 0.4 mL/h, 0.6 mL/h) in an electrospinning route, potassium dihydrogen phosphate (KDP)–polyethylene oxide (PEO) nanofibers with different diameters were successfully prepared. Scanning electron microscopy (SEM) showed the formation of PEO nanofiber morphology with average diameters of 410 nm, 435 nm, and 439 nm for flow rates of 0.1 mL/h, 0.4 mL/h, and 0.6 mL/h, respectively. Using x-ray diffraction (XRD), the presence of KDP in the fiber matrix was confirmed from the intense diffraction peak at 2θ = 24°, which corresponds to the (200) plane of KDP, and the nanofiber exhibited variation in crystallite size, ranging from 30 nm to 41 nm with different flow rates. The lattice strain of the prepared samples decreased with increasing flow rate. A blueshift in the absorption edge and an increase in optical band gap were observed for spun fibers (215 nm, 6.04 eV) with bulk KDP (280 nm, 5.82 eV) due to changes in the dielectric properties of the material. From the recorded photoluminescence (PL) spectra, dominant green emission at 565 nm was observed. Electrospun KDP-PEO nanofibers exhibited a frequency doubling phenomenon with relative SHG efficiency twice that of KDP. In addition, intensity-dependent Z-scan measurements were performed with a Q-switched neodymium-doped yttrium aluminium garnet (Nd:YAG) laser as an excitation source (532 nm, 5 ns, 10 Hz). The excited-state absorption process played a dominant role in the observed nonlinearity in the KDP-PEO nanofibers. The demonstrated sequential two-photon absorption-based optical limiting action makes KDP-PEO nanofibers a versatile optical limiting material for eye safety devices against intense laser pulse.

Graphic Abstract

中文翻译：

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磷酸二氢钾 (KDP)-聚氧化乙烯 (PEO) 电纺纳米纤维的激发态吸收辅助光学限制作用

通过在静电纺丝路线中采用不同的流速（0.1 mL/h、0.4 mL/h、0.6 mL/h），成功制备了不同直径的磷酸二氢钾（KDP）-聚环氧乙烷（PEO）纳米纤维。扫描电子显微镜 (SEM) 显示 PEO 纳米纤维形态的形成，平均直径为 410 nm、435 nm 和 439 nm，流速分别为 0.1 mL/h、0.4 mL/h 和 0.6 mL/h。使用 X 射线衍射 (XRD)，从 2 θ 处的强衍射峰证实纤维基质中存在 KDP= 24°，对应于 KDP 的 (200) 面，纳米纤维表现出微晶尺寸的变化，范围从 30 nm 到 41 nm，具有不同的流速。制备的样品的晶格应变随着流速的增加而降低。由于材料介电特性的变化，观察到具有体 KDP (280 nm, 5.82 eV) 的纺成纤维 (215 nm, 6.04 eV) 的吸收边缘蓝移和光学带隙增加。从记录的光致发光 (PL) 光谱中，观察到 565 nm 处的主要绿色发射。电纺 KDP-PEO 纳米纤维表现出倍频现象，其相对 SHG 效率是 KDP 的两倍。此外，使用 Q 开关掺钕钇铝石榴石 (Nd:YAG) 激光器作为激发源 (532 nm, 5 ns, 10 赫兹）。激发态吸收过程在 KDP-PEO 纳米纤维中观察到的非线性中起主导作用。所展示的基于连续双光子吸收的光学限幅作用使 KDP-PEO 纳米纤维成为一种用于抵御强激光脉冲的眼睛安全装置的通用光学限幅材料。

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