Pakhomov A V, Löchner F J F, Zschiedrich L, Saravi S, Hammerschmidt M, Burger S, Pertsch T, Setzpfandt F
JCMwave GmbH, 14050, Berlin, Germany.
Institute of Applied Physics, Abbe Center of Photonics, Friedrich Schiller University Jena, 07745, Jena, Germany.
Sci Rep. 2020 Jun 29;10(1):10545. doi: 10.1038/s41598-020-67186-0.
We analyse possibilities to quantitatively evaluate the surface second-order optical nonlinearity in noncentrosymmetric materials based on polarization-resolved analysis of far-field radiation patterns of second-harmonic generation. We analytically demonstrate that for plane-wave illumination the contribution to the second-harmonic signal from the surface of a nonlinear medium exhibits different polarization properties and angular dependencies compared to the contribution from the bulk. In view of this, we optimize the illumination geometry in order to enable the most efficient separation and comparison of both nonlinearities. Furthermore, we consider the illumination of an AlGaAs slab by a tightly-focused linearly-polarized Gaussian beam as an alternative measurement geometry. It is found that the reliable separation of the surface nonlinearity contribution as well as a wide range of detectable values can be achieved with this geometry as well.
我们基于对二次谐波产生的远场辐射图案的偏振分辨分析，分析了定量评估非中心对称材料中表面二阶光学非线性的可能性。我们通过分析证明，对于平面波照明，非线性介质表面对二次谐波信号的贡献与体材料的贡献相比，表现出不同的偏振特性和角度依赖性。鉴于此，我们优化照明几何结构，以便最有效地分离和比较这两种非线性。此外，我们考虑用紧聚焦的线偏振高斯光束照射AlGaAs平板作为一种替代测量几何结构。结果发现，采用这种几何结构也能可靠地分离表面非线性贡献，并获得广泛的可检测值。
