Laser Physics Center, Research School of Physics and Engineering, Australian National University, ACT, Australia.
Opt Lett. 2012 Sep 15;37(18):3864-6. doi: 10.1364/ol.37.003864.
We study the second-harmonic generation in quadratic nonlinear media with localized spatial modulation of χ((2)) response. We demonstrate that the emission of Čerenkov second-harmonic takes place only when the fundamental beam illuminates the region of χ((2)) variation. This proves that the sharp modulation of the χ((2)) nonlinearity constitutes a sufficient condition for the emission of Čerenkov second harmonic in bulk materials. Our calculations are in excellent agreement with simple analytical approach utilizing the concept of reciprocal vectors representing the Fourier spectrum of the modulation of χ((2)).
我们研究了具有 χ((2)) 响应局部空间调制的二次非线性介质中的二次谐波产生。我们证明，只有当基频光束照射到 χ((2)) 变化区域时，才会发射切伦科夫二次谐波。这证明了 χ((2)) 非线性的急剧调制是在体材料中发射切伦科夫二次谐波的充分条件。我们的计算与利用代表调制 χ((2)) 的傅里叶谱的倒易矢量概念的简单分析方法非常吻合。
