飞秒激光脉冲作用熔石英的超快传热动力学研究

Ultrafast heat transfer dynamics induced by femtosecond laser pulse in fused silica

  • 摘要: 飞秒激光具有超短脉冲宽度、超高峰值功率的特点,飞秒激光与物质作用表现出的非线性吸收和低热扩散特性,使其在高精密微纳器件加工中有着重要的应用前景。建立了针对飞秒激光脉冲与熔石英作用的瞬态光电离以及非平衡传热的超快动力学模型。通过数值求解该模型获得了飞秒激光单脉冲作用熔石英的载流子密度和非平衡电子与声子温度的时空演化;得到了在非平衡态条件下,电声耦合时间随激光能量密度、脉冲宽度的近线性调控规律。进一步研究得到了瞬态电子热导、热容、电声耦合系数的变化规律,并对上述模拟现象进行了分析和探讨。

     

    Abstract: Femtosecond laser interacts with material shows nonlinear absorption and low thermal diffusion due to the ultrashort pulse width and ultrahigh peak power, which makes it important in the manufacturing of high-precision micro-nano devices. An ultrafast dynamic model for transient photoionization and non-equilibrium heat transfer of femtosecond laser pulses interacting with fused silica was established. By numerical solution, the spatio-temporal evolution of carrier density and non-equilibrium electron and phonon temperature of fused silica excited under femtosecond laser single pulse was obtained, and the nearly linear regulation law of electron-phonon coupling time with laser energy density and pulse width under non-equilibrium conditions was obtained. The variation laws of transient electron thermal conductivity, thermal capacity and electron-phonon coupling coefficient were further investigated in details. And the above simulation results were analyzed and discussed.

     

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