In Fig.4, two dimensional scale model of Y-shaped branch waveguide is illustrated. From port 1, continuous electric field with Gaussian profile along with vertical axis are given. The electromagnetic field is composed of unique electric field which is oriented to vertical direction to the paper surface and magnetic fields which are parallel to L0 and W0 axes. Therefore, the incident wave is E-polalization. Spot size 2w0 of the Gaussian profile corresponds to waveguide full width √3P, where P = 26.5mm is lattice period. Dielectric