Focusing characteristics of polarized second-harmonic emission at non-Ising polar domain walls

Non-Ising polar domain walls have recently emerged as individual two-dimensional materials exhibiting localized nonlinear optical emission. The analysis of this emitted light often requires focusing with high apertures. As a result, the vectorial properties come into play. This study provides an analytic treatment vector fields’ effect on polarized second-harmonic emission (SHG) arising at walls. While confined fields are expected to alter SHG polarization response, we identify extrinsic and intrinsic capable canceling effects. We determine precise combination fundamental wave orientation which effects negligible. Furthermore, perimeter defined by parameters below negligible is extracted from systematic focus-dependent analysis. Our necessary methodology precautions probe internal structure non-Ising fields, it can be extended explore newly discovered ferroelectric topologic nanostructures.