Enhanced second-harmonic generation in coupled microcavities based on all-silicon photonic crystals

The enhancement of second-harmonic generation (SHG) in one-dimensional coupled photonic-crystal microcavities (CMC) formed from mesoporous silicon is observed. Peaks in the angular spectrum of the second-harmonic intensity are correlated with angular positions of the split CMC modes and caused by combination of the resonant enhancement of the fundamental radiation and constructive interference of the second-harmonic fields induced in the microcavity spacers. The shape of the SHG resonances is shown to be dependent on the variation of the electromagnetic coupling between the microcavities controlled by reflectivity of the intermediate distributed Bragg reflector.