2ND-HARMONIC GENERATION IN A PHOTONIC CRYSTAL

Phase matched second harmonic generation is observed experimentally in a centrosymmetric ne crystalline lattice of dielectric spheres of opt ical dimensions. The inversion symmetry is broken locally at the surfa ce of each sphere in such a way that the scattered second harmonic lig ht interferes constructively leading to a nonvanishing macroscopic fie ld. Phase matching of the fundamental and second harmonic waves in suc h periodic lattice is observed to be naturally provided by the bending of the photon dispersion curve at the edge of the Bragg reflection ba nd of a given set of lattice planes. (C) 1997 American Institute of Ph ysics.