Patent ID: 7457497

Claim:
An optical multiplexer/demultiplexer, comprising: a first optical waveguide provided on a first side of a member having the first side and a second side defined by a groove and has one end exposed to the groove; a second optical waveguide provided on the first side and has one end exposed to the groove; a third optical waveguide provided on the second side and has one end exposed to the groove; and an optical filter inserted in the groove, the optical filter transmits a light component of a longer wavelength and reflects a light component of a shorter wavelength, wherein in a plan view, the first optical waveguide is provided along a straight line extending from a first edge of the first side of the member to a second edge of the second side of the member, the second edge opposite the first edge, the first optical waveguide and the third optical waveguide are optically connected with each other by transmission of the optical filter, the first optical waveguide and the second optical waveguide are optically connected with each other by reflection of the optical filter, the third optical waveguide is provided along a straight line extending from the second edge to the groove, the longer wavelength component propagates in the first optical waveguide and the third optical waveguide and passes through the optical filter, and the transmitted light propagates in the other of the first optical waveguide and the third optical waveguide, and the shorter wavelength component propagates in one of the first optical waveguide and the third optical waveguide and is reflected by the optical filter, and the reflected light propagates to the other of the first optical waveguide and the third optical waveguide.