Nanostructured nonlinear optical (NLO) materials are attracting increasing interest as optical limiters for various applications. In this study, one-dimensional nanostructured Na2Ti3O7 was synthesized by a typical hydrothermal method and systematically characterized. The results showed that one-dimensional nanostructured Na2Ti3O7 has good crystallinity and thermal stability. Its morphology can be easily controlled to form nanotubes, nanobelts and nanorods by altering the amounts of added NaOH. The robustness of the NLO properties of one-dimensional nanostructured Na2Ti3O7 in broadband optical limiting (OL) applications was investigated by the open-aperture Z-scan method. At laser wavelengths of 532 nm and 1064 nm, the effective nonlinear extinction coefficients showed nonmonotonic dependence on the morphology; nanotubes gave the maximum value. The results confirmed that the NLO and OL responses of one-dimensional nanostructured Na2Ti3O7 can be effectively optimized by tailoring the morphology. In addition, the nonlinear extinction coefficients of these three types of one-dimensional nanostructured Na2Ti3O7 are better than those of multi-walled carbon nanotubes, a benchmark one-dimensional OL material, at 532 nm and 1064 nm; they therefore have potential applications in nonlinear optics. Nonlinear scattering and photothermal effect measurements showed that the OL shown by one-dimensional nanostructured Na2Ti3O7 can be mainly attributed to nonlinear scattering and free-carrier absorption at both irradiation wavelengths. The fabrication of one-dimensional nanostructured Na2Ti3O7 with different morphologies via this simple approach paves the way for the synthesis and tuning of new one-dimensional materials with desirable photonic properties for various applications.

中文翻译：

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通过形态控制优化一维纳米结构钛酸钠的非线性光学响应

纳米结构非线性光学 (NLO) 材料作为各种应用的光学限制器越来越受到关注。在这项研究中，一维纳米结构的 Na2钛3○7通过典型的水热法合成并系统表征。结果表明，一维纳米结构的 Na2钛3○7具有良好的结晶度和热稳定性。通过改变 NaOH 的添加量，可以很容易地控制其形态以形成纳米管、纳米带和纳米棒。一维纳米结构 Na 的 NLO 特性的稳健性2钛3○7通过开放孔径 Z 扫描方法研究了在宽带光学限制 (OL) 应用中的应用。在 532 nm 和 1064 nm 的激光波长处，有效非线性消光系数表现出对形貌的非单调依赖性；纳米管给出了最大值。结果证实，一维纳米结构 Na 的 NLO 和 OL 响应2钛3○7可以通过剪裁形态进行有效优化。此外，这三种一维纳米结构 Na 的非线性消光系数2钛3○7在 532 nm 和 1064 nm 处优于基准一维 OL 材料多壁碳纳米管；因此，它们在非线性光学中具有潜在的应用。非线性散射和光热效应测量表明，一维纳米结构 Na2钛3○7可以主要归因于两个辐照波长的非线性散射和自由载流子吸收。一维纳米结构Na的制备2钛3○7通过这种简单的方法具有不同的形态，为合成和调整具有所需光子特性的新一维材料铺平了道路，适用于各种应用。