Efficient second and third harmonic generation in dual-layer lithium niobate microdisk resonator

Lithium niobate thin film frequency doubler has extensive applications in the preparation of classical and quantum sources. In this study, we successfully fabricated microdisk resonators with a quality factor of 2.2×105 in reverse-polarization dual-layer x-cut lithium niobate for the first time. Based on the modal phase matching condition, efficient second harmonic generation with a record normalized conversion efficiency of ∼56000