We propose the design of low-loss waveguide Y branches with coherently coupled bends. According to results of beam-propagation simulations, the excess loss of a complete Ti:LiNbO3 Y branch with a nominal half-branching angle of 1° can be as low as -0.18 dB. Similar to the case of other cascaded Y branches, when two coherently coupled Y branches are cascaded, the power distribution at the output varies with the length of the straight connecting waveguide. Details of the Y-branch design that gives low loss and equal power splitting are presented.
© 1991 Optical Society of America
F. S. Chu and Pao-Lo Liu, "Low-loss coherent-coupling Y branches," Opt. Lett. 16, 309-311 (1991)