Dielectric superlattice: effect of coupling coefficients on quasi-phase-matched harmonic generation

Coupled optical parametric processes in an dielectric superlattice were analyzed theoretically. The efficient quasi-phase-matched third-harmonic (TH) generation depends not only on the magnitude of the coupling coefficients but also on their ratio. It was found that all the fundamental energy can be transferred to the third harmonic at a particular ratio. In other cases, there exists, an optimum condition corresponding to a maximum third harmonic conversion efficiency. The result is of practical important for the design of TH device.