Abstract The self-organized FePt nanoparticles were embedded in single crystal MgO matrix using pulse laser deposition method. The increasing FePt nanoparticles spacing (2–10 nm) were observed as the decrease of FePt deposition pulse number. The spacing between the FePt nanoparticles changing causes many subbands rooting in superlattice structure. With the decrease of the spacing, the mechanism of samples third-order nonlinear optical property revealed that the two-photonic absorption replaces saturated absorption. By adjusting the FePt deposition pulse number from 100 to 900 P, the third-order nonlinear polarizability χ(3) initially increased, and then decreased. The highest third-order nonlinear polarizability χ(3) of 4.1 × 10−10 esu was obtained with the deposition pulse number of 500 P. In combination with the small linear absorption α, the FePt NPs: MgO system is enough to become a prime candidate for nonlinear application near 580 nm.

中文翻译：

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FePt纳米颗粒复合薄膜的间距相关非线性光学研究

摘要 采用脉冲激光沉积法将自组织FePt纳米颗粒嵌入单晶MgO基体中。随着 FePt 沉积脉冲数的减少，观察到 FePt 纳米颗粒间距的增加（2-10 nm）。FePt 纳米粒子之间的间距变化导致许多子带扎根于超晶格结构。随着间距的减小，样品三阶非线性光学性质的机制揭示了双光子吸收取代饱和吸收。通过将 FePt 沉积脉冲数从 100 P 调整到 900 P，三阶非线性极化率 χ(3) 先增大后减小。在 500 P 的沉积脉冲数下获得了最高的三阶非线性极化率 χ(3) 为 4.1 × 10−10 esu。结合较小的线性吸收 α，