US 2012/0230631 A1Published application

Optical hybrid circuit, optical receiver, optical transceiver, and light receiving method

AssigneeFujitsu Limited

InventorSeok-Hwan JEONG

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Abstract

An optical hybrid circuit includes an MMI coupler including input channels provided at positions symmetrical first output channels, and second output channels, to convert multilevel modulation signal into first and second optical signals each having an in-phase relationship; first optical coupler coupled to one of the first and the second output channels, and having a branching ratio of 85:15 or 15:85, to convert the first optical signals into third optical signals having a 45- or 135-degree phase relationship; second optical coupler coupled to the other of the first and the second output channels, and having a same branching ratio as that of the first optical coupler, to convert the second optical signals into fourth optical signals having a 135- or 45-degree phase relationship; and a phase controlling region provided on at least one of one of the first output channels and one of the second output channels.

Claims20

Dependent claims

An optical hybrid circuit comprising:

a multimode interference coupler including a pair of input channels provided at positions symmetrical with each other with respect to a center position in a widthwise direction thereof, a pair of first output channels adjacent with each other to output a pair of first optical signals having an in-phase relationship with each other, and a pair of second output channels adjacent with each other to output a pair of second optical signals having an in-phase relationship with each other, the multimode interference coupler being adapted to convert multilevel modulation signal light into the pair of first optical signals having an in-phase relationship with each other and the pair of second optical signals having an in-phase relationship with each other;
a first optical coupler coupled to one of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a branching ratio of 85:15 or 15:85, the first optical coupler being adapted to convert the first optical signals into a pair of third optical signals having a 45- or 135-degree phase relationship with each other;
a second optical coupler coupled to the other of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a same branching ratio as the branching ratio of the first optical coupler, the second optical coupler being adapted to convert the second optical signals into a pair of fourth optical signals having a 135- or 45-degree phase relationship with each other;
and
at least one phase controlling region provided on at least one of one of the pair of first output channels and one of the pair of second output channels.

2 more elements

An optical receiver comprising:

an optical hybrid circuit comprising:
a multimode interference coupler including a pair of input channels provided at positions symmetrical with each other with respect to a center position in a widthwise direction thereof, a pair of first output channels adjacent with each other to output a pair of first optical signals having an in-phase relationship with each other, and a pair of second output channels adjacent with each other to output a pair of second optical signals having an in-phase relationship with each other, the multimode interference coupler being adapted to convert multilevel modulation signal light into the pair of first optical signals having an in-phase relationship with each other and the pair of second optical signals having an in-phase relationship with each other;
a first optical coupler coupled to one of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a branching ratio of 85:15 or 15:85, the first optical coupler being adapted to convert the first optical signals into a pair of third optical signals having a 45- or 135-degree phase relationship with each other;
a second optical coupler coupled to the other of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a same branching ratio as the branching ratio of the first optical coupler, the second optical coupler being adapted to convert the second optical signals into a pair of fourth optical signals having a 135- or 45-degree phase relationship with each other;
and
at least one phase controlling region provided on at least one of one of the pair of first output channels and one of the pair of second output channels;
a photodiode adapted to convert the third optical signals outputted from the first optical coupler and the fourth optical signals outputted from the second optical coupler into an analog electric signal;
an analog-digital conversion circuit adapted to convert the analog electric signal outputted from the photodiode into a digital electric signal;
and
a digital electric circuit adapted to execute arithmetic processing using the digital electric signal outputted from the analog-digital conversion circuit.

7 more elements

An optical transceiver comprising:

an optical hybrid circuit comprising:
a multimode interference coupler including a pair of input channels provided at positions symmetrical with each other with respect to a center position in a widthwise direction thereof, a pair of first output channels adjacent with each other to output a pair of first optical signals having an in-phase relationship with each other, and a pair of second output channels adjacent with each other to output a pair of second optical signals having an in-phase relationship with each other, the multimode interference coupler being adapted to convert multilevel modulation signal light into the pair of first optical signals having an in-phase relationship with each other and the pair of second optical signals having an in-phase relationship with each other;
a first optical coupler coupled to one of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a branching ratio of 85:15 or 15:85, the first optical coupler being adapted to convert the first optical signals into a pair of third optical signals having a 45- or 135-degree phase relationship with each other;
a second optical coupler coupled to the other of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a same branching ratio as the branching ratio of the first optical coupler, the second optical coupler being adapted to convert the second optical signals into a pair of fourth optical signals having a 135- or 45-degree phase relationship with each other;
and
at least one phase controlling region provided on at least one of one of the pair of first output channels and one of the pair of second output channels;
a photodiode adapted to convert the third optical signals outputted from the first optical coupler and the fourth optical signals outputted from the second optical coupler into an analog electric signal;
an analog-digital conversion circuit adapted to convert the analog electric signal outputted from the photodiode into a digital electric signal;
and
a digital electric circuit adapted to execute arithmetic processing using the digital electric signal outputted from the analog-digital conversion circuit.

7 more elements

A light receiving method comprising:

converting, using a multimode interference coupler including a pair of input channels provided at positions symmetrical with each other with respect to a center position in a widthwise direction thereof, a pair of first output channels adjacent with each other to output a pair of first optical signals having an in-phase relationship with each other, and a pair of second output channels adjacent with each other to output a pair of second optical signals having an in-phase relationship with each other, multilevel modulation signal light into the pair of first optical signals having an in-phase relationship with each other and the pair of second optical signals having an in-phase relationship with each other;
controlling a phase difference between a pair of optical signals of at least one of the pair of first optical signals and the pair of second optical signals, with at least one phase controlling region provided on at least one of one of the pair of first output channels and one of the pair of second output channels;
converting the pair of first optical signals into a pair of third optical signals having a 45- or 135-degree phase relationship with each other, using a first optical coupler coupled to one of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a branching ratio of 85:15 or 15:85;
converting the pair of second optical signals into a pair of fourth optical signals having a 135- or 45-degree phase relationship with each other, using a second optical coupler coupled to the other of the first output channels and the second output channels, having two channels on the input side thereof and two channels on the output side thereof, and having a same branching ratio as the branching ratio of the first optical coupler;
and
receiving the pair of third optical signals and the pair of fourth optical signals.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/357,520Filed 24 Jan 2012
Priority: JP 2011-0513719 Mar 2011
Published: 13 Sep 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G02B 6/12004
Of the integrated circuit kind: combinations of two or more optical elements
H04B 10/615
Coherent receivers: arrangements affecting the optical part of the receiver
G02B 6/2813
Using a mixing element which evenly distributes an input signal over a number of outputs: based on multimode interference effect, i.e. self-imaging
G02B 2006/12061
Materials: silicon