High optical damage threshold on-chip lithium tantalate microdisk resonator.

Lithium tantalate (LT) is one of the most attractive optical nonlinear materials, as it possesses a high optical damage threshold and great UV transparency (0.28-5.5 µm). Recently, optical grade LT nanoscale film was developed. Here a high-quality-factor (∼105) LT microdisk resonator based on LT-on-insulator (LTOI) film is fabricated by utilizing focused ion beam (FIB) milling. 2 µW output second-harmonic waves are achieved in the LTOI microdisk at about 500 mW input power. Cascaded third-harmonic generation is also observed in the fabricated device. This work may pave the way for LTOI in integrated photonic chips.