Analysis of asymmetric fringe patterns of third-harmonic generation in a molecular crystal

The asymmetric Maker fringe pattern of third-harmonic generation in an anisotropic molecular crystal is analyzed to evaluate the third-order optical susceptibility χ(3). Analysis of a diethyl-amino-nitro-stilbene crystal shows that the molecular axes are not oriented parallel to the crystal surface, but are about 45° relative to the surface. The χ(3) value parallel to the orientation of the molecular axis is estimated to be 1.0×10−11 esu, corresponding to about ten times the χ(3) value perpendicular to that axis.