Quasi-phase-matched harmonic generation through coupled parametric processes in a quasiperiodic optical superlattice

We have investigated and fabricated an optical superlattice of LiTaO3, in which two building blocks, each containing a pair of antiparallel 180° ferroelectric domains, were arranged as a Fibonacci sequence. The second- and third-harmonic generation in this structure have been studied and measured. The results verifies that the second-harmonic spectrum and the third harmonic may be generated in a quadric nonlinear medium by a series of quasi-phase-matching processes. The experimental results are in good agreement with theory.