US 7,469,079 B2
Broadband wavelength multiplexing and demultiplexing filter and optical splitter with optical signal multiplexing and demultiplexing function
Kazutaka Nara, Tokyo (Japan); Haruki Urabe, Tokyo (Japan); Tsunetoshi Saitoh, Tokyo (Japan); and Masahito Morimoto, Tokyo (Japan)
Assigned to The Furukawa Electric Co., Ltd., Tokyo (Japan)
Appl. No. 10/560,132
PCT Filed Jan. 25, 2005, PCT No. PCT/JP2005/001295
§ 371(c)(1), (2), (4) Date Dec. 09, 2005,
PCT Pub. No. WO2005/071453, PCT Pub. Date Aug. 04, 2005.
Claims priority of application No. 2004-016589 (JP), filed on Jan. 26, 2004; application No. 2004-188365 (JP), filed on Jun. 25, 2004; and application No. 2004-222250 (JP), filed on Jul. 29, 2004.
Prior Publication US 2007/0104409 A1, May 10, 2007
Int. Cl. G02B 6/12 (2006.01)
U.S. Cl. 385—15  [385/14; 385/24] 18 Claims
OG exemplary drawing
 
1. A broadband wavelength multiplexing and demultiplexing filter comprising:
Mach-Zehnder optical interferometer circuits each having directional couplers formed on a substrate by a first optical waveguide and a second waveguide provided in parallel to each other with a gap in a lengthwise direction of the optical waveguides therebetween, and a phase part interposed between the directional couplers;
a first point-symmetrically connected optical interferometer circuit formed by accurately point-symmetrically connecting two equal Mach-Zehnder optical interferometer circuits in series; and
a light input side circuit formed by connecting one or more first point-symmetrically connected optical interferometer circuits in series;
wherein a light input terminal of a first optical waveguide of the light input side circuit is composed of an input port for optical signals having a plurality of wavelengths, and an output terminal of the first optical waveguide is composed of a through port,
an output terminal of a second optical waveguide of the light input side circuit is composed of a cross port,
a first light output side circuit formed by serially connecting one or more second point-symmetrically connected optical interferometer circuits having the same functional structure as the first point-symmetrically connected optical interferometer circuit is connected to the through port, and
a second light output side circuit including one or more Mach-Zehnder optical interferometer circuits having transmission characteristics different from those of the Mach-Zehnder optical interferometer circuits constituting the first and the second point-symmetrically connected optical interferometer circuits is connected to the cross port.