This paper compares two methods of research of nonlinear optical phenomenon in lithium niobate (LiNbO₃) crystals. Photorefractive effect is studied by direct and fractal analysis of photoinduced light scattering (PILS) patterns appearing in LiNbO₃:Zn (0.018–0.88 wt%) crystals and round scattering appearing in LiNbO₃:Zn (2.05 wt%) under laser radiation. Fractal analysis of PILS patterns has been established to be a source of more precise information about laser-induced defects causing PILS and thus, on LN crystals properties. Fractal analysis is able to show dynamics of laser-induced defect distribution in time under action of a laser radiation, while direct analysis of PILS patterns shows only static properties of LN crystals.

本文比较了两种研究铌酸锂（LiNbO ₃）晶体非线性光学现象的方法。通过对在激光辐射下LiNbO ₃：Zn（0.018–0.88 wt％）晶体中出现的光诱导光散射（PILS）模式和在LiNbO ₃：Zn（2.05 wt％）中出现的圆形散射进行直接和分形分析，研究了光折变效应。已经建立了对PILS图案的分形分析，以获取有关引起PILS的激光诱导缺陷以及有关LN晶体特性的更精确信息。分形分析能够在激光辐射的作用下及时显示出激光诱导的缺陷分布的动态变化，而直接分析PILS图案仅显示LN晶体的静态特性。