掺铯铌酸锂晶体光致声发射机制的研究

Excitation of Light-induced Acoustic Waves in Doped Lithium Niobate Crystals

在掺铯铌酸锂晶体的光折变效应中,观察到了由光生伏特场所致的空间电荷场波(SCWS),以及沿晶体自发极化方向上正、反二列超声波被SCWS所激发的低频调制放大波.在光致准击穿时,它的周期与同时测量的光生伏特电流和晶体某一点衍射光强的跃变周期相同,而且随入射光强的增加而变小.应用SCWS与二列超声波相互作用的共振态理论分析了这一现象,实验结果与理论分析一致.

The phenomena of acoustic emission in doped lithium niobate crystals have been observed in the process of light-induced quasi-breakdown. It is found that the ultrasonic waves introduced into the crystal have been modulated by the low frequency acoustic waves. Its frequency increases with the rise of the intensity of incident light and its jump period of breakdown is the same as that of the photovoltaic current and the diffracted light intensity. This effect is explained with the interaction of the three waves and resonant state theory. The experimental results and the theoretical analysis are in conformity.