| 摘要 |
PURPOSE:To obtain a three-dimensional light branching device low in branching loss and able to make branching angle large by connecting two branch waveguides having the same section and the same refractive index with a main waveguide to the main waveguide path in Y-form through a transitional area having a rectangular section and a specified refractive index, and providing a cladding of low refractive index enclosing it. CONSTITUTION:Branch waveguide paths 2, 3 having the same section and refractive index with the main waveguide 1 are connected to the main waveguide having sectional form of 2Tx in width, 2Ty in height and its refractive index is n2 in Y-form making an opening angle to 2theta through a transitional area 4 having a rectangular section and a refractive index n3, and a cladding 6 that encloses it and having a refractive index n1 lower than n2 is provided. By satisfying n3=n2[Sin<2>psi+cfs<2>(theta+psi)]<1/2> where psi is an angle made by a ray for waveguide mode transmitted in the main waveguide 1 and a transmission axis, a three-dimensional light branching device low in branching loss and capable of making branching angle 2 large can be obtained. |
