Design of a low-loss Y-branch optical waveguide

A low-loss Y-branch optical waveguide with a wide gap between two output waveguides was designed. Its performance was simulated by the beam propagation method. In spite of its wider gap, the excess loss was much less than that in the case of conventional Y-branches. The wider gap is desirable for better step coverage in buried waveguides (e.g. silica waveguides).