| 摘要 |
PURPOSE:To obtain branched light with excellent transmission characteristics while suppressing the mode conversion loss of transmission light by optically coupling a main line with a tap fiber without reducing the radius of curvature of a main line optical fiber too small. CONSTITUTION:The main line optical fiber 1 consists of a multi-mode optical fiber having a core 3 and a clad 5 and a part of light in a waveguide mode is converted into clad mode light at a mode conversion area 8 in a bent part 1a. Since a gap between the area 8 and the one end part 2a of the tap fiber 2 is filled with a light translucent material 7 having >=1 diffractive index, the clad mode light in the area 8 can be lead into the material 7 and made incident on the fiber 2. Since only a part of the waveguide mode light is converted into the clad mode light in the area 8 without converting the clad mode light up to radiation mode light and it is unnecessary to reduce the radius R of curvature of the bend part 1a too small, the mode conversion loss of the transmission light can be suppressed. |
