Optical waveguides – Accessories – Attenuator
Reexamination Certificate
2008-06-17
2008-06-17
Healy, Brian M (Department: 2883)
Optical waveguides
Accessories
Attenuator
C385S011000, C385S042000, C385S014000, C385S129000, C385S130000
Reexamination Certificate
active
07389033
ABSTRACT:
A planar lightwave circuit type variable optical attenuator with a small polarization dependent loss is provided. By setting the waveguide birefringence (absolute value) in first and second optical coupler sections equal to or greater than 3.5×10−4, the polarization mode coupling is made equal to or less than −25 dB, and the effect of the polarization dependence caused by the polarization mode coupling at the cross port of the first and second optical couplers is suppressed. In addition to or independently of this, the arm waveguide length can be designed to be equal to an integer multiple of the optical beat length obtained by dividing a used optical wavelength by the waveguide birefringence.
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Hashizume Yasuaki
Inoue Yasuyuki
Saida Takashi
Sugita Akio
Healy Brian M
Nippon Telegraph and Telephone Corporation
Workman Nydegger
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