| 摘要 |
PURPOSE:To easily reduce the size of the optical circulator by providing a mode selection part and a unidirectional mode conversion part on a 1st branch waveguide and common waveguide of an optical waveguide formed on one surface of a substrate. CONSTITUTION:Light which travels from a 1st port 24 to a common port 24 is not demultiplexed and propagated to the common 20, but light which travels from the common port 20 to the 1st port 24 is demultiplexed and propagated even to the 2nd port 28. A mode selection part 34 is provided to a 1st branch waveguide 26 to pass only part of the light propagated in a 1st branch waveguide 26 which is in predetermined propagation mode and cut off the light in other propagation modes. The unidirectional mode conversion part 36 is provided to the common waveguide 22 and does not convert the propaga tion mode of light passing through the mode selection part 34, but converts the propagation mode of the light traveling from the common port 20 to the 1st port 24 and 2nd port 28 into a propagation mode wherein the light is cut off by the mode selection part 34. Consequently, the optical circulator is easily reduced in size. |
