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研究了不同脉冲能量下1kHz飞秒激光脉冲在石英玻璃内部诱导的损伤痕迹、纳米光栅结构及其双折射特性,发现在激光辐照区域顶端形成的微纳结构具有两种周期性:沿光传输方向的周期为ΛK;沿激光偏振方向的周期为ΛE.通过数值模拟飞秒脉冲在石英玻璃内部的传输过程,研究了入射能流密度分布及自由电子密度分布对双周期纳米光栅结构的影响.结果表明,较大的入射能流密度有利于纳米光栅的形成,且产生的电子密度会影响周期ΛK,电子密度越大,周期ΛK越大.从理论上分析了双周期纳米光栅结构的形成过程,认为等离子体非对称生长及其引起的局域场强分布影响了双周期纳米光栅结构的形成.
The damage trace induced by 1 kHz femtosecond laser pulses at different pulse energies, the structure of nanorods and their birefringence properties were investigated. It was found that there are two kinds of periodicity in the micro-nano structure formed at the top of laser irradiation region: The period of the direction is ΛK and the period along the polarization direction of the laser is Λ E. The numerical simulation of the transmission of femtosecond pulses inside the quartz glass shows that the effect of the incident energy flux density and the free electron density distribution on the bi- The results show that the larger incident fluence facilitates the formation of nanorods, and the electron density produced will affect the period Λ K. The larger the electron density, the larger the period Λ K. The formation process of the nanowire structure with two periods is theoretically analyzed It is considered that the asymmetric growth of plasma and the local field intensity distribution caused by it affect the formation of double-period nanorod structures.