Integrated Lithium Niobate Microring Resonators Fabricated With 515 nm Femtosecond Laser Ablation

Lithium niobate (LiNbO3, LN) on insulator (LNOI) is a promising material platform for integrated photonics to realize high-capacity and high-speed information communication. Here, we developed the 515 nm femtosecond laser micro-machining technique with a 316 nm processing accuracy and demonstrated the fabrication of monolithically integrated waveguide-coupled micro-resonators with the quality factors (Q) of 1.8× 105 using 515 nm femtosecond laser ablation assisted ions beam etching (IBE) process. The chemical-mechanical polishing (CMP) is adopted to smoothing the etched edge of the hard mask patterned by femtosecond laser ablation. These fabrication techniques are compatible with high efficiency and high precision wafer-scale production, without counting on the UV/E-beam lithography technique, which is essential for LN photonic devices moving towards industrial applications.