Scattering phenomenon has been extensively investigated in nature. In general, scattering of light could be a detrimental effect in some fields, such as optical communication and imaging system, but it could also be beneficial in others. For instance, scattering could be used to discover structure information and physical properties of the materials relating to light-matter interaction. Not limited in linear optics, such scattering phenomenon has also been reported in processes of nonlinear frequency conversion. For instance, in nonlinear photonic crystals (NPCs), scattering-assisted second harmonic generation has been carefully studied. Nevertheless, the limitations of such special structured NPCs are the complex fabrication and fixed properties. Hence, how to manipulate the nonlinear signal pattern in real time has become an urgent issue.

In this paper we studied scattering-assisted SHG process of structured FW, whose phase front is periodically modulated. In the case of 1D structure of FW, the multiple-conical SH was observed and the position measured in experiments was consistent with theoretical analysis. Extending such structured FW to 2D case, scattering-assisted SH belts were also observed in experiments. This method not only allows dynamic control of the scattering-assisted SH signal, but also has potential applications in various nonlinear frequency conversion processes, such as nonlinear Raman-Nath diffraction, nonlinear Bragg diffraction and nonlinear Cerenkov radiation, etc.

The research was reported by "Haigang Liu, Jun Li, Xiangling Fang, Xiaohui Zhao, Yuanlin Zheng, and Xianfeng Chen, Scattering-assisted second harmonic generation of structured fundamental wave, Optics Express, 24(21), 24137-24142 (2016)"