The mechanism of a femtosecond laser-induced breakdown of deposited substrates mediated by aluminum nanoparticles in a vacuum environment was studied. This model of optical breakdown mediated by aluminum nanoparticles includes the electromagnetic field model for the description of near-field enhancement of aluminum nanoparticles, the two-temperature model for the description of electron and lattice temperature of aluminum nanoparticles, and the plasma model for the description of the evolution of electron density in the deposited substrate. These three physical field models were fully coupled in this model. We defined a new modified dielectric function model to describe the dielectric function of aluminum nanoparticles, due to the strength of near-field enhancement depends on the size and morphology of nanoparticles. The near-field enhancement of different types of aluminum nanoparticles, the femtosecond laser breakdown threshold of deposited substrates, and the evolution of the lattice temperature of aluminum nanoparticles were investigated. The results showed that assembled aluminum nanoparticles can significantly reduce the femtosecond laser breakdown threshold of deposited substrates in a vacuum, and the lattice temperature of aluminum nanoparticle was lower than the melting point, under the irradiation of a single-pulse femtosecond laser with a wavelength of 800 nm and pulse width of 25 fs.

中文翻译：

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真空中铝纳米颗粒介导的飞秒激光诱导沉积衬底击穿机理研究

研究了在真空环境中由铝纳米颗粒介导的飞秒激光诱导的沉积基板击穿的机制。这种由铝纳米粒子介导的光击穿模型包括描述铝纳米粒子近场增强的电磁场模型、描述铝纳米粒子电子和晶格温度的双温度模型和描述铝纳米粒子的等离子体模型。沉积基板中电子密度的演变。这三个物理场模型在该模型中完全耦合。由于近场增强的强度取决于纳米粒子的尺寸和形态，我们定义了一个新的改进的介电函数模型来描述铝纳米粒子的介电函数。研究了不同类型铝纳米粒子的近场增强、沉积衬底的飞秒激光击穿阈值以及铝纳米粒子晶格温度的演变。结果表明，组装的铝纳米粒子在真空中可显着降低沉积衬底的飞秒激光击穿阈值，并且在波长为 100 米的单脉冲飞秒激光照射下，铝纳米粒子的晶格温度低于熔点。 800 nm 和 25 fs 的脉冲宽度。