Fang Xinyuan, Kuang Zeyu, Chen Peng, Yang Haocheng, Li Qian, Hu Wei, Lu Yanqing, Zhang Yong, Xiao Min
Opt Lett. 2017 Nov 1;42(21):4387-4390. doi: 10.1364/OL.42.004387.
We experimentally investigate the second-harmonic generation of a high-order Laguerre-Gaussian (LG) mode under the quasi-phase-matching (QPM) configuration. First, we introduce a simple method to observe the azimuthal (l) and radial (p) indices of the high-order LG modes. Based on the astigmatic transformation technique, l and p are revealed in the number of dark stripes of the converted pattern in the focal plane. Then, using this efficient method of measurement, we demonstrate in experiments a second-harmonic LG mode with its radial and azimuthal indices being twice those of the inputted fundamental wave through QPM in a periodically poled KTP crystal. Our results provide a feasible way to obtain simultaneously the LG modes with larger radial and azimuthal indices.
我们通过实验研究了准相位匹配（QPM）配置下高阶拉盖尔 - 高斯（LG）模式的二次谐波产生。首先，我们介绍一种简单方法来观察高阶LG模式的方位角（l）和径向（p）指数。基于像散变换技术，l和p可通过焦平面上转换图案的暗条纹数量揭示出来。然后，利用这种高效的测量方法，我们在实验中展示了通过周期性极化KTP晶体中的QPM产生的二次谐波LG模式，其径向和方位角指数是输入基波的两倍。我们的结果为同时获得具有更大径向和方位角指数的LG模式提供了一种可行的方法。
