Second Harmonic Conical Waves for Symmetry Studies in χ(2) Nonlinear Photonic Crystals

In this work, we further exploit the usefulness of quadratic second harmonic generated patterns from a chi((2)) two-dimensional ferroelectric domain structure to reveal the symmetry of trigonal ferroelectric crystals. Via conical-type second harmonic generation we show that the intrinsic symmetry properties of the crystal can be visualized to the naked eye by simply rotating the crystal around its polar axis. We demonstrate how this approach can goes a step further in crystallographic studies allowing us to distinguish changes on the sign of the crystallographic axis in bulk crystals. (C) 2011 The Japan Society of Applied Physics