Patent ID: 6819859
Filing Date: 2004-11-16
Classification: G02F

Abstract:
A planar lightwave circuit type variable optical attenuator including a Mach-Zehnder interferometer formed on a substrate, said Mach-Zehnder interferometer comprising:two optical waveguide arms formed on said substrate; and thin-film heaters formed respectively over said two optical waveguide arms, said two optical waveguide arms having lengths not equal to each other, wherein assuming that an effective refractive index of said optical waveguide arms is neff, a difference between the lengths of said optical wave guide arms is &Dgr;L0, and a central wavelength of an operating wavelength band is &lgr;0, the following relationship is satisfied: 0.36Ã—&lgr;0/neff&lE;&Dgr;L0&lE;0.47Ã—&lgr;0/neff.