Nanocrystal materials with modified symmetry

Changes in crystallographic symmetry introduced by nanostructuring of mater ials are studied. Crystal point-group symmetry analysis qualitatively expla ins the main properties of birefringence observed in experiments with nanop orous silicon, provides a deeper understanding of phase-matching abilities of nanocrystal materials in nonlinear optics, and allows tensor properties of linear and nonlinear-optical parameters of nanostructured materials to b e predicted and analyzed in a systematic way.