PROFILE OF TITANIUM LINES PRODUCED BY EXCIMER LASER DIRECT WRITING ON LITHIUM-NIOBATE

The profile of titanium (Ti) lines produced by KrF excimer laser direct writing on lithium niobate (LiNbO3) has been investigated in detail since it is critical in the fabrication of Ti in-diffused LiNbO3 optical waveguides. Lines written at speeds varying from 0.5 to 10 mu-m/s have typical thicknesses and linewidths varying from 10 to 185 nm and from 2 to 24-mu-m, respectively. At a low power density E, the maximum thickness t is proportional to the number of photons or the power density. Increasing E allows a sufficient heating, which leads to the diffusion of Ti into LiNbO3, resulting in a sharp decrease of the thickness in the middle of the deposited line.