Simultaneous high-efficiency and equal-level second- and third-harmonic generation achieved by controllable linear gratings in a quasiperiodic optical superlattice

We report a theoretical study of the simultaneous high-efficiency, equal-level outputs of second and third harmonics in a quasiperiodic optical superlattice at any given fundamental intensity. The principle is that nonlinear coupling is effectively controlled by introducing proper quasiphase mismatches, by use of the tunability of linear refractive index gratings induced by applying a dc electric field based on the electro-optic effect. The theoretical results verify that this approach is feasible and very efficient. In addition, we also make a comparison with temperature tuning control, demonstrating that the performance of electro-optic control is much better than that of temperature tuning control.