| 摘要 |
PURPOSE:To reduce insertion loss and to improve performance by providing a beam diameter conversion part on a connection end side of an optical fiber for connection or an optical waveguide for connection with an optical waveguide switch. CONSTITUTION:When a laser beam is made incident from the open end of the input side optical fiber 61 for connection, a light beam diameter is enlarged gradually according to the reduction of a specific refractive index difference in the beam diameter conversion part 62, and the laser beam arrives at the input side optical waveguide 31 of a matrix optical waveguide. At this time, since the specific refractive index differences of the optical waveguides 31, 32 are formed to a value smaller than the specific refractive index difference of a single mode optical fiber for communication, the laser beam made incident on the input side optical waveguide 31 is transmitted while holding a light beam with a large beam diameter thereafter also. Thereafter, the light beam made incident on the output side optical fiber 72 for connection from the output side optical waveguide 32 whose beam diameter is reduced gradually according to the increase of the specific refractive index difference in the beam diameter conversion part 72, and becomes the beam diameter equal to the single mode optical fiber for communication finally. |
