Schematic of the proposed frequency-conversion scheme for LiTaO3.

Abstract: We investigate efficient fourth-harmonic generation in a single two-dimensional ({2D}) quadratically nonlinear photonic crystal. We propose a novel parametric process that starts with phase-matched generation of a pair of symmetric second-harmonic waves, which then interact to produce a fourth-harmonic wave that is collinear to the fundamental. We show that this process is more efficient than conventional fourth-harmonic-generation schemes by a factor that reaches 4 at low intensities and discuss how to design and optimize the nonlinear {2D} photonic crystals that are implemented in {{LiNbO}$_3$} and {{LiTaO}$_3$}.

Copyright © by the respective publisher. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the publisher.