Giant enhancement of second harmonic generation in a finite photonic crystal with a single defect and dual-localized modes

We present a one-dimensional defective photonic crystal containing the nonlinear medium, with a single defect and dual-localized modes. Giant enhancement of second harmonic generation is predicted in numerical simulation. The mechanism is the strong localizations of fundamental wave and second harmonic in the single defect, simultaneously. Such a kind of structures can be expected as high-efficency nonlinear photonic devices.