Optical communications – Receiver – Including optical element
Reexamination Certificate
2009-04-03
2011-12-13
Vanderpuye, Kennneth N (Department: 2613)
Optical communications
Receiver
Including optical element
C398S155000, C398S161000, C398S162000
Reexamination Certificate
active
08078067
ABSTRACT:
In an optical receiving apparatus for receiving an optical DQPSK signal, a phase difference between both arms of an optical interferometer is controlled to an optimum value. The optical DQPSK signal is incident on two optical interferometers in each which a delay-time difference between two arms is set to be equal to a 1-symbol time of the optical DQPSK signal and which are orthogonal to each other. The optical receiving apparatus converts the optical DQPSK signal into an intensity signal and receives it. A differential amplifier obtains a difference signal between outputs of a pre-amplifier and a discriminator connected thereto. The difference signal includes, as an amplitude, a phase shift in a phase section. A control circuit adjusts the phase of the phase section in the optical interferometers to reduce this difference signal, and changes the phase difference between the two arms to a desired phase difference.
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Black-Childress Rajsheed
Hitachi , Ltd.
Mattingly & Malur, PC
Vanderpuye Kennneth N
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