Phase matched third harmonic generation in 3D photonic crystal

In this paper, we present experimental evidence of phase matched third harmonic generation at 355 nm from a beam at 1064 nm incident on a photonic crystal made of 120 nm in diameter polystyrene spheres ordered in an fee lattice. Numerical calculations show that at the lower angle edge of the Bragg reflected band, the periodical structure induced effective index of refraction at 355 nm matches the index of refraction at 1064 nm.