LOW-LOSS TI-LINBO3-WAVE-GUIDE BENDS PREPARED BY MGO INDIFFUSION

A significant bend loss reduction for z-cut Ti: LiNbO3 waveguides is achieved with a single and very efficient technique. We have decreased the refractive index on the outer sides of an S bend through indiffusion of a double-MgO layer for reducing the radiation losses, and used a broadening of the bent waveguide sections 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. © 1990 IEEE