通过分析不同泵浦光强下简并瞬态吸收过程我们获得了GaN薄膜的非线性光动力学过程如下：电子在价带通过吸收一个光子跃迁到导带由于价带吸收截面大于导带的吸收截面导致GaN薄膜表现为瞬态饱和吸收。改写成英语。

Through analysis of the degenerate transient absorption process under different pump intensities, we have obtained the nonlinear optodynamics of GaN thin films as follows: Electrons in the valence band transition to the conduction band by absorbing a photon, and due to the valence band having a larger absorption cross-section than the conduction band, GaN thin films exhibit transient saturation absorption.