Developing an Open-Source Data Analysis Package for Optical Second Harmonic Generation

Optical second harmonic generation (SHG) is a process in which the frequency of light incident on a sample is doubled through its second-order nonlinear interactions with the material. It is a powerful tool to detect the symmetry breaking in a crystal by directly probing the nonlinear susceptibility tensor elements in a rotational anisotropic (RA) measurement. Recent years have seen the impressive development of the RA-SHG technique in discovering novel phases in quantum materials. Data analysis of an RA-SHG pattern is based on the simulation of nonlinear optical signals including electric dipole, electric quadrupole, and magnetic dipole response under given experimental geometry and point group symmetry of the crystal. An SHG simulation package will benefit the community by promoting the efficiency of data analysis. Here, we present our work of developing an open-source RA-SHG data analysis package. We develop a graphical user interface that can implement universal RA-SHG simulation of an arbitrary experimental geometry and the 32 crystallographic point groups. Our simulation will produce a functional model of RA-SHG data and a priori polar plot patterns with tunable tensor elements. Future implementation will integrate artificial intelligence (AI). AI will be used to collect experimental data from literature to establish a training database and generate polar plot patterns with predicted values of the tensor elements.