The article presents the results of an in-situ pump–probe study of the change’s kinetics in the optical properties of GeTe thin films associated with reversible phase transitions initiated by nanosecond laser pulses. It was shown that the change of the transmissivity and reflectivity of GeTe films in case of direct phase transition from the amorphous state to the crystalline starts at the same time, while the reverse transition is observed delay change of the transmissivity relative to the reflectivity. The value of this delay for the 100 nm GeTe thin film was estimated at t₁₀₀ = 24 ns, and for the 50 nm sample – t₅₀ = 13 ns. This time lag in changes of the transmissivity from the reflectivity in case of reamorphization films depending on sample thickness, can be explained by the high contrast of the concentration of free electrons between amorphous and crystalline states, which determine the reflectivity of the surface layer of the sample, while the transmissivity is determined by the total thickness. The experimental dependences of the kinetics of changes in the optical properties of GeTe samples under laser-induced phase transitions are in good consistent with the numerical simulation data of the Stefan problem.

本文介绍了与纳秒激光脉冲引发的可逆相变相关的 GeTe 薄膜光学特性变化动力学的原位泵浦探针研究结果。结果表明，在从非晶态到晶态的直接相变的情况下，GeTe 薄膜的透射率和反射率的变化同时开始，而观察到的反向转变是透射率相对于反射率的延迟变化。100 nm GeTe 薄膜的延迟值估计为t ₁₀₀  = 24 ns，而对于 50 nm 样品 – t ₅₀ = 13 纳秒。在重新定型膜的情况下，根据样品厚度，透射率与反射率变化的这种时间滞后可以通过非晶态和晶态之间自由电子浓度的高对比度来解释，这决定了表面层的反射率样品，而透射率由总厚度决定。GeTe 样品在激光诱导相变下光学性质变化动力学的实验依赖性与 Stefan 问题的数值模拟数据非常一致。