Dual-periodically poled lithium niobate microcavities supporting multiple coupled parametric processes

Periodically poled lithium niobate (PPLN) microcavities with additional reciprocal vectors attract attention as a platform for efficient parametric nonlinear optical processes with wavelength and polarization flexibility. Here, we report the simultaneous realization of multiple coupled parametric processes in PPLN microdisk cavities with dual periods as a result of the significantly increased number of reciprocal vectors to fulfill quasi-phase matchings for a series of nonlinear processes. PPLN microdisks with up to 1.43×10⁵ quality factors and unit domain size of 90 nm in width were fabricated using CMOS compatible microfabrication techniques and electrically poled with the help of piezoresponse force microscopy. The conversion efficiency of second-harmonic signal was measured to be 51%W^-1. Our work paves the way towards efficient cascaded parametric effects including third- and fourth-harmonic generations.