论文标题
在双重介质中的随机准阶段匹配的建模
Modeling of Random Quasi-Phase-Matching in Birefringent Disordered Media
论文作者
论文摘要
我们提供了一个矢量模型，以模拟双重透明介质中的第二次谐波生成（SHG），并具有非线性（$χ^{（2）} $）晶粒的任意配置。我们将此模型应用于Linbo $ _3 $和BATIO $ _3 $晶粒的无序组件上，以确定双折射对随机准阶段匹配过程的影响。我们表明，在单分散的组件中，双折射会放松SHG效率的晶粒尺寸依赖性。在具有足够大的晶粒的多分散组件中，我们发现双折射引入了SHG效率提高高达54％，而粒度参考晶体则是晶粒尺寸独立的。如果双重晶粒可以相匹配，则这种增强与晶粒尺寸线性增加。这两种不同的尺度行为用于Kurtz和Perry的粉末技术，以识别材料的相匹配性。我们以linbo $ _3 $和ADP的示例显示，当谷物变得小于相干长度时，无法应用此技术，因为具有晶粒尺寸的SHG缩放是特定于物质的。
We provide a vectorial model to simulate second-harmonic generation (SHG) in birefringent, transparent media with an arbitrary configuration of non-linear ($χ^{(2)}$) crystalline grains. We apply this model on disordered assemblies of LiNbO$_3$ and BaTiO$_3$ grains to identify the influence of the birefringence on the random quasi-phase-matching process. We show that in monodispersed assemblies, the birefringence relaxes the grain-size dependence of the SHG efficiency. In polydispersed assemblies with sufficiently large grains, we find that the birefringence introduces an SHG efficiency enhancement of up to 54% compared to isotropic reference crystals, which is grain size independent. This enhancement increases linearly with the grain size, if the birefringent grains can be phase matched. These two different scaling behaviours are used in Kurtz and Perry's powder-technique to identify the phase-matchability of a material. We show on the example of LiNbO$_3$ and ADP that this technique cannot be applied when the grains get smaller than the coherence length, because the SHG scaling with the grain size becomes material specific.
