Second harmonic generation from arrays of subwavelength cylinders

Abstract

We show that periodic arrays of thin dielectric cylinders with dielectric constant higher than that of surrounding media can be used for an efficient second harmonic generation. The amplitude of the second harmonic reaches its absolute maximum when the fundamental and second harmonic fields are both in resonance with trapped modes (quasistationary states) of the structure. It is shown that the double resonance condition together with the phase matching condition for the second harmonic generation can be achieved by a suitable choice of the array geometry. The physical reason for the efficient second harmonic generation is an enhancement of electromagnetic fields on the cylinders at resonances, and a long interaction time between fundamental and second harmonic fields trapped by the structure. The same structure can be used within a wide range of the incident radiation wavelength, because the resonant conditions are shown to be always satisfied through the choice of the angle of incidence.