Low-loss Ti:LiNbO3-waveguide bends prepared by MgO indiffusion

A significant bend loss reduction for z-cut Ti:LiNbO₃ waveguides was achieved with a single and very efficient technique. The refractive index on the outer sides of an S bend was decreased through indiffusion of a double-MgO layer for reducing the radiation losses, and a broadening of the bent waveguide sections was used for further decreasing of the radiation losses and additionally reducing the transition losses. The acceptable bend radius for an allowed excess loss of 1 dB could thus be reduced from 24 mm down to 5 mm for TM polarization and from 26 mm down to 10 mm for TE polarization