US 8,285,152 B2Granted

DQPSK optical receiver

AssigneeFujitsu Limited

InventorsYuichi Akiyama, Toshiki Tanaka

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Abstract

According to an aspect of an embodiment, a DQPSK optical receiver, comprising: a first LPF connected to a line branching off from between a first optical-electrical converter and a first data recovery circuit; a second LPF connected to a line branching off from between a second optical-electrical converter and a second data recovery circuit; a first LIA for amplifying a signal output from the first LPF and also limiting an amplitude of an output signal thereof; a second LIA for amplifying a signal output from the second LPF and also limiting an amplitude of an output signal thereof; a first mixer for multiplying the output signal from the first LIA by a signal output from the second LPF; and a second mixer for multiplying the output signal from the second LIA by a signal output from the first LPF.

Claims12

Dependent claims

A Differential Quadrature Phase Shift Keying (DQPSK) optical receiver to receive and demodulate a DQPSK-modulated optical signal, comprising:

a first interferometer associated with a first arm;
a second interferometer associated with a second arm;
first optical-electrical converter to convert an optical signal output from the first interferometer to an electrical signal;
second optical-electrical converter to convert an optical signal output from the second interferometer to an electrical signal;
first and second low pass filters coupled to respective lines branching off from between the first optical-electrical converter and a first clock and data recovery circuit;
third and fourth low pass filters coupled to respective lines branching off from between the second optical-electrical converter and a second clock and data recovery circuit;
a first limiting amplifier to amplify a signal output from the first low pass filter and also to limit an amplitude of an output signal thereof;
a second limiting amplifier to amplify a signal output from the third low pass filter and also to limit an amplitude of an output signal thereof;
a first mixer to multiply the output signal from the first limiting amplifier by a signal output from the fourth low pass filter;
and
a second mixer to multiply the output signal from the second limiting amplifier by a signal output from the second low pass filter.

8 more elements

A Differential Quadrature Phase Shift Keying (DQPSK) optical receiver to receive and demodulate a DQPSK-modulated optical signal, comprising:

a first interferometer associated with a first arm;
a second interferometer associated with a second arm;
first optical-electrical converter to convert an optical signal output from the first interferometer to an electrical signal;
second optical-electrical converter to convert an optical signal output from the second interferometer to an electrical signal;
first and second low pass filters coupled to respective lines branching off from between the first optical-electrical converter and a first clock and data recovery circuit;
third and fourth low pass filters coupled to respective lines branching off from between the second optical-electrical converter and a second clock and data recovery circuit;
a first limiting amplifier coupled between branch points to which the first and second low pass filters associated with the first arm are respectively coupled;
a second limiting amplifier coupled between branch points to which the third and fourth low pass filters associated with the second arm are respectively coupled;
a first mixer to multiply an output of the first low pass filter by an output of the fourth low pass filter;
and
a second mixer to multiply an output of the third low pass filter by an output of the second low pass filter.

8 more elements

Dependencies are inferred from the claim text.