| 摘要 |
PURPOSE: To provide a wavelength demultiplexing element which is low in transmission and reflection loss and has high isolation. CONSTITUTION: A filter member 20 constituted by forming an wavelength demultiplexing filter 5 on a filter substrate 13 is so disposed in mid-way of a straight optical waveguide 3 for input and output so as to intersect therewith at an intersection angleα. Of the light rays of wavelengthsλ1 ,λ2 entering from the incident side 8 of this optical waveguide 3 for input and output, the light ray of the wavelengthλ2 is transmitted by the wavelength demultiplexing filter 5 and is emitted from an exit side 9. The light ray of the wavelengthλ1 is reflected in a direction deviating from the optical waveguide 3 for input and output by a reflection surface 6. A straight optical waveguide 1 for receiving the reflected light which receives the reflected light is formed in this reflection direction apart a spacing from the optical waveguide 3 for input and output to receive the reflected light of the wavelengthλ1 from a reflected light receiving end 10 and is emitted from an end 11 side after light receiving. The optical waveguide 3 for input and output and the optical waveguide 1 for receiving the reflected light are spaced from each other, by which the increase in the loss by the interaction of the incident light and the reflected light, etc., are suppressed. |
