AbstractThe deposition of titanium lines by KrF excimer laser direct writing on lithium niobate (LiNbO3) has been investigated. A detailled study of the line profile has been performed since this is critical in the fabrication of Ti:LiNbO3 optical waveguides. We show that at a low power density E, the maximum thickness t is proportional to E, while increasing E leads to the diffusion of Ti into LiNbO3 resulting in a saturation and even a decrease in thickness. Preliminary results on Ti:LiNbO3 optical waveguides show that their characteristics are similar to those made by conventional methods.
We develop a technique for realizing lithium niobate on insulator (LNOI) waveguides of a multi-centimeter-length with a propagation loss as low as 0.027 dB/cm. Our technique relies on patterning a chromium (Cr) thin film coated on the top surface of LNOI into a hard mask with a femtosecond laser followed by the chemo-mechanical polishing for structuring the LNOI into the waveguides. The surface roughness on the waveguides is determined to be 0.452 nm with an atomic force microscope (AFM). The approach is compatible with other surface patterning technologies such as optical and electron beam lithographies or laser direct writing, enabling high-throughput manufacturing of large-scale LNOI-based photonic integrated circuits.
Low-Loss Lithium Niobate on Insulator (LNOI) Waveguides of a 10 cm-Length and a Sub-Nanometer Surface Roughness