LiNbO_3:Fe晶体二波耦合弱光放大的物理机理

Study on the mechanism of light amplification in iron-doped lithium niobate crystals

对LiNbO3:Fe晶体中二波耦合过程进行了动态观测 .进一步探讨了LiNbO3:Fe晶体中弱光放大的物理机理 .发现LiNbO3:Fe晶体中二波耦合过程的弱光放大对c轴指向有明显的依赖关系 ,虽然光生伏打效应对光生载流子的迁移有主要贡献 ,但扩散机理的贡献仍不可忽略 .弱光最终得到放大是瞬态能量转移与扩散机理引起的能量转移的共同贡献 .弱光放大达到准稳态之后的下降过程为瞬态能量转移的时间指数衰减过程与光散射引起的能量耗散的共同贡献 .

The study on the light amplification mechanism of iron-doped lithium niobate crystals has been done systematically. The experimental results indicate that the light amplification depends on the c-axis direction of the crystal. We propose a new view for the light amplification mechanism of the two-wave mixing in iron-doped lithium niobate crystals: The diffusion mechanism cannot be neglected, and the light amplification mechanism in doped lithium niobate crystals is caused by both the diffusion and the transient energy transfer. The decrease of the amplified light intensity after the steady-state is due to the decreases, of the transient energy transfer with time and the energy dissipation caused by the beam fanning.