A polarization splitter on LiNbO3 using only titanium diffusion

A novel polarization splitter is proposed for use in integrated optical circuits on lithium niobate. In contrast to previously reported devices, its operation is based on the mode sorting effect with no external control, while its fabrication requires only a single technology: the diffusion of titanium. The splitter is formed by a Y junction. The polarization splitting can be achieved by making the output waveguides from two titanium strips with different dimensions. A realistic design of these output guides is presented, and some technological aspects are discussed. The operation of the polarization splitter is investigated with the beam propagation method. The results show that a 15-dB extinction ratio is obtained with branching angles larger than 0.2°. The extinction ratio can be as high as 30 dB with a branching angle of 0.1°. The excess losses are below 0.05 dB