Patent ID: 7110639

Claim:
A lightwave circuit device comprising first to third Mach-Zehnder interferometers and an optical switch, wherein the first to third Mach-Zehnder interferometers each comprise first to third ports, a first optical coupler whose one end is optically coupled to the first port, first and second optical waveguides optically coupled to the other end of the first optical coupler, a second optical coupler optically coupled to the first and the second optical waveguides and the second and the third ports, and a first heater provided along at least one of the first and the second optical waveguides, the second port of the first Mach-Zehnder interferometer and the first port of the second Mach-Zehnder interferometer are optically coupled, and the third port of the first Mach-Zehnder interferometer and the first port of the third Mach-Zehnder interferometer are optically coupled, and the optical switch comprising: a third optical coupler whose one end is optically coupled to the first port of the first Mach-Zehnder interferometer; third and fourth optical waveguides optically coupled to the other end of the third optical coupler; a fourth optical coupler whose one end is optically coupled to the third and the fourth optical waveguides; fifth and sixth optical waveguides optically coupled to the other end of the fourth optical coupler; a fifth optical coupler whose one end is optically coupled to the fifth and the sixth optical waveguides; a second heater provided along at least one of the third and the fourth optical waveguides; and a third heater provided along at least one of the fifth and the sixth optical waveguides.