Journal Article <論文・報告>蛍石単結晶内部のフェムト秒レーザー集光誘起構造変化の応力ダイナミクスの観測

吉永, 公平

1pp.66 - 69 , 2016-03 , 京都大学学際融合教育研究推進センター高大接続科学教育ユニット
工学 光誘起構造改質
In this study, we observed the dynamics inside a calcium fluoride (CaF2) single crystal following photoexcitation by a tightly focused femtosecond laser pulse. This observation method is based on a pumpprobe method and a polarization microscope. The observed dynamics indicated the generation of a stress wave and cracks generated from the photoexcited region. The stress wave had a characteristic shape due to anisotropy of the crystal’s elastic properties. The crack propagation occurred along the (110) planes. We determined the time evolution of the stress in a stress wave and estimated the temperature elevation in the photoexcited region by comparing our observed results with the results from a thermo-elastic simulation. The simulation results of the stress at a temperature elevation of 1000 K in the photoexcited region were in good agreement with our experimental results in the <100> directions, but we obtained lower stress values in the <110> directions. This discrepancy may be due to the fact that the thermo-elastic simulation did not take the influence of crack generation into consideration.

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