Low-loss coherent-coupling Y branches.
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:LiNbO(3) Y branch with a nominal half-branching angle of 1 degree 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.
Department of Electrical and Computer Engineering, State University of New York at Buffalo, Amherst, New York 14260, USA.
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