Fabrication of Low Loss Lithium Niobate Rib Waveguides Through Photoresist Reflow

We present lithography and argon plasma etching of lithium niobate on insulator (LNOI) rib waveguides using reflowed photoresist etch masks 405 nm photolithography. Melting the at temperatures greatly exceeding its glass transition temperature while minimizing feature distortion through adhesion control reduces sidewall surface roughness allows to be used both as pattern mask hard mask. Waveguide surfaces exhibiting sub-nm root mean square are fabricated. Dependence angle width, propagation loss thermal annealing fabricated devices is characterized. Measured quality factors microresonators exceed one million. LNOI resonators with low increase nonlinear optical conversion efficiencies useful for efficient electro-optic modulation. Photolithography compatible fabrication photonic integrated circuits facilitates scalable commercialization.