Lithium niobate micro-disk resonators of quality factors above 10⁷

We report on the fabrication of crystalline lithium niobate microresonators with quality factors above 10⁷, as measured around 770 nm wavelength. Our technique relies on femtosecond laser micromachining for patterning a mask coated on the lithium niobate on insulate (LNOI) into a microdisk, followed by a chemo-mechanical polishing process for transferring the disk-shaped pattern to the LNOI. Nonlinear processes including second-harmonic generation and Raman scattering have been demonstrated in the fabricated microdisk.