Second harmonic generation via excitation of the surface modes of a one-dimensional photonic crystal

A multilayer structure is presented that sustains propagation of two optical surface waves, one at the fundamental frequency and one at the second harmonic frequency, with the same effective refractive indices at both frequencies. Phase matching of these two surface waves and localisation of the field maxima at the layer boundaries allow us to observe generation of the second harmonic, despite the fact that the structure is composed of centrosymmetric materials, for which the second-order nonlinear susceptibility vanishes in the electric dipole approximation.