Depolarisation in Ti:LiNbO3 waveguides and its effect on circuit design

Ti: LiNbO3 waveguides are analysed to determine their depolarisation properties. Depolarisation in 3 cm-long x-cut crystals is consistently ?30 to ?35 dB, suggesting there is an inherent mechanism limiting the crosstalk to this level. Substantial improvement in crosstalk can only be achieved by placing polarising elements at the sample ends.