# US 2014/0193152 A1 · Signal transmission method, signal receiving method, passive optical network pon device, and pon system

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- Number: US 2014/0193152 A1
- Document ID: US20140193152A1
- Status: Published application
- Kind: A1
- Application number: 14/209,221
- Filed: 2014-03-13
- Published: 2014-07-10
- Earliest claimed: 2011-09-15
- Assignees: The Hong Kong Polytechnic University; Huawei Technologies Co., Ltd.
- Applicants: The Hong Kong Polytechnic University; Huawei Technologies Co., Ltd.
- Inventors: Lei ZHOU; Guo WEI; Chao LV; Dawei WANG; Botao LIU
- Web page: https://patentgrep.com/patent/US20140193152A1

## CPC

- H04B 10/27: Arrangements for networking
- H04B 10/532: Polarisation modulation
- H04B 10/614: {comprising one or more polarization beam splitters, e.g. polarization multiplexed [PolMux] X-PSK coherent receivers, polarization diversity heterodyne coherent receivers (H04J14/06 takes precedence)}
- H04B 10/6151: {comprising a polarization controller at the receiver's input stage}
- H04J 14/02: Wavelength-division multiplex systems
- H04B: TRANSMISSION
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

Embodiments of the present disclosure relate to a signal transmission method The signal receiving method includes: receiving a first transmit signal, where the first transmit signal includes a first polarized optical signal and a second polarized optical signal that are perpendicular to each other, where the first polarized optical signal is loaded with first data, the first transmit signal is an uplink signal, and the first data is uplink data, or, the first transmit signal is a downlink signal, and the first data is downlink data; splitting the first transmit signal into a first signal and a second signal according to power; separately rotating a first polarized optical signal and a second polarized optical signal of the second signal by 90 degrees; and performing coherent mixing on the rotated second signal and the first signal to obtain the first data.

## Claims

### Claim 1

A transmitter, comprising a signal source, a polarization beam splitter, a modulator, and a polarization beam combiner, wherein
the signal source generates an optical signal, and inputs the optical signal to the polarization beam splitter;
the polarization beam splitter splits the optical signal into a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, inputs the first polarized optical signal to the modulator, and inputs the second polarized optical signal to the polarization beam combiner;
the modulator modulates the first polarized optical signal, loads first data into the first polarized optical signal, and inputs the modulated first polarized optical signal to the polarization beam combiner; and
the polarization beam combiner synthesizes the modulated first polarized optical signal and the second polarized optical signal into a first transmit signal, and transmits the first transmit signal to a receiving end.

### Claim 2

A receiver, comprising a first power splitter, a first director of a first optical signal, a polarization rotator of light, and a coherent receiver, wherein
the first power splitter splits a first transmit signal sent by a transmitting end into a first signal and a second signal according to power, inputs the first signal to the coherent receiver, and inputs the second signal to the first director of the first optical signal, wherein the first transmit signal comprises a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, wherein the first polarized optical signal is loaded with first data;
the first director of the first optical signal is connected to the polarization rotator of light, and the first director of the first optical signal is configured to input the second signal to the polarization rotator of light;
the polarization rotator of light separately rotates a first polarized optical signal and a second polarized optical signal of the second signal by 90 degrees, and inputs the rotated second signal to the first director of the first optical signal; and the first director of the first optical signal inputs the rotated second signal to the coherent receiver; and
the coherent receiver performs coherent mixing on the rotated second signal and the first signal to obtain the first data.

### Claim 3 (depends on 2)

The receiver according to claim 2, wherein the coherent receiver comprises an optical hybrid, an optical-to-electrical converter, an analog to digital converter, and a digital signal processor, wherein
the optical hybrid performs coherent mixing on the rotated second signal and the first signal and outputs four channels of optical signals;
the optical-to-electrical converter performs optical-to-electrical conversion on the four channels of optical signals to output two channels of electrical signals;
the analog to digital converter is configured to perform analog to digital conversion on the two channels of electrical signals; and
the digital signal processor is configured to perform digital processing on the two channels of electrical signals that are output after the analog to digital conversion to obtain the first data.

### Claim 4 (depends on 2)

The receiver according to claim 2, wherein the first director of the first optical signal includes a circulator, and the circulator comprises a first input port, a second input port, a first output port, and a second output port, wherein
the first input port receives the first transmit signal, and inputs the first transmit signal to the polarization rotator of light through the first output port; the second input port receives the rotated second signal, and inputs the rotated second signal to the first coherent receiver through the second output port.

### Claim 5 (depends on 2)

The receiver according to claim 2, wherein the polarization rotator of light includes a Faraday rotation mirror FRM, and the FRM comprises a Faraday rotator FR and a reflective mirror, wherein
the FR separately rotates the first polarized optical signal and the second polarized optical signal of the second signal by 45 degrees, the second signal that has been rotated by 45 degrees is reflected back to the FR by the reflective mirror, and the FR separately rotates the first polarized optical signal and the second polarized optical signal of the second signal that have been rotated by 45 degrees by 45 degrees again.

### Claim 6 (depends on 1)

A passive optical network (PON) central office device, comprising the transmitter of claim 1, wherein the first data is downlink data, the first transmit signal is a downlink signal, and the receiving end is a PON terminal device.

### Claim 7 (depends on 6)

The PON central office device according to claim 6, further comprising a second director of a second optical signal and a first receiver, wherein
the second director of the second optical signal transmits the downlink signal synthesized by the polarization beam combiner to the PON terminal device, receives an uplink signal sent by the PON terminal device, and inputs the uplink signal to the first receiver, wherein the uplink signal comprises a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, wherein the first polarized optical signal and the second polarized optical signal are loaded with uplink data;
the signal source inputs the generated optical signal to the first receiver; and
the first receiver performs coherent mixing on the first transmit signal and the optical signal to obtain the uplink data.

### Claim 8 (depends on 6)

The PON central office device according to claim 6, wherein the first receiver demodulates, using a constant modulus algorithm CMA, the first polarized optical signal and the second polarized optical signal of the uplink signal to obtain the uplink data loaded into the second polarized optical signal of the uplink signal and discards invalid data loaded into the second polarized optical signal of the uplink signal, wherein the uplink signal is obtained by the PON terminal device by loading the uplink data into a fourth signal which is split from the downlink signal according to power.

### Claim 9 (depends on 7)

The PON central office device according to claim 7, wherein the second director of the second optical signal includes a circulator, and the circulator comprises a first input port, a second input port, a first output port, and a second output port, wherein
the first input port receives the downlink signal, and transmits the downlink signal to the PON terminal device through the first output port; and the second input port receives the uplink signal and inputs the uplink signal to the first receiver through the second output port.

### Claim 10 (depends on 2)

A passive optical network (PON) terminal device, comprising the receiver of claim 2, wherein the first data is downlink data, the first transmit signal is a downlink signal, and the transmitting end is a PON central office device.

### Claim 11 (depends on 10)

The PON terminal device according to claim 10, further comprising a second power splitter and a second transmitter, wherein
the second power splitter splits the downlink signal sent by the PON central office device into a third signal and a fourth signal according to power, inputs the third signal to the first power splitter for coherent reception, and inputs the fourth signal to the second transmitter; and
the second transmitter modulates the fourth signal, loads uplink data into a first polarized optical signal and a second polarized optical signal of the fourth signal, and transmits the modulated fourth signal as an uplink signal to the PON central office device.

### Claim 12 (depends on 1)

A passive optical network (PON) terminal device, comprising the transmitter of claim 1, wherein the first data is uplink data, the first transmit signal is an uplink signal, and the receiving end is a PON central office device.

### Claim 13 (depends on 12)

The PON terminal device according to claim 12, further comprising a third director of a third optical signal and a third receiver, wherein
the third director of the third optical signal transmits the uplink signal synthesized by the polarization beam combiner to the PON central office device, receives a downlink signal sent by the PON central office device, and inputs the downlink signal to the third receiver, wherein the downlink signal comprises a first polarized optical signal and a second polarized optical signal, wherein the first polarized optical signal and the second polarized optical signal are loaded with downlink data;
the signal source inputs the generated optical signal to the third receiver; and
the third receiver performs coherent mixing on the second transmit signal and the optical signal to obtain the downlink data.

### Claim 14 (depends on 13)

The PON terminal device according to claim 13, wherein the third receiver demodulates, using a constant modulus algorithm CMA, the first polarized optical signal and the second polarized optical signal of the downlink signal to obtain the downlink data loaded into the second polarized optical signal of the downlink signal and discards invalid data loaded into the second polarized optical signal of the downlink signal, wherein the downlink signal is obtained by the PON central office device by loading the downlink data into a fourth signal which is split from the uplink signal according to power.

### Claim 15 (depends on 13)

The PON terminal device according to claim 13, wherein the third director of the third optical signal includes a circulator, and the circulator comprises a first input port, a second input port, a first output port, and a second output port, wherein
the first input port receives the uplink signal, and transmits the uplink signal to the PON central office device through the first output port; and the second input port receives the downlink signal, and inputs the downlink signal to the third receiver through the second output port.

### Claim 16 (depends on 2)

A passive optical network (PON) central office device, comprising the receiver of claim 2, wherein the first data is uplink data, the first transmit signal is an uplink signal, and the transmitting end is a PON terminal device.

### Claim 17

A passive optical network (PON) system, comprising at least one PON central office device and at least one PON terminal device
wherein the at least one PON central office device comprises a first transmitter, wherein the first transmitter comprises a signal source, a polarization beam splitter, a modulator, and a polarization beam combiner, wherein
the signal source generates an optical signal, and inputs the optical signal to the polarization beam splitter;
the polarization beam splitter splits the optical signal into a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, inputs the first polarized optical signal to the modulator, and inputs the second polarized optical signal to the polarization beam combiner;
the modulator modulates the first polarized optical signal, loads first data into the first polarized optical signal, and inputs the modulated first polarized optical signal to the polarization beam combiner; and
the polarization beam combiner synthesizes the modulated first polarized optical signal and the second polarized optical signal into a first transmit signal, and transmits the first transmission signal to a receiving end, wherein the first data is downlink data, the first transmit signal is a downlink signal, and the receiving end is the at least one PON terminal device;
wherein the at least one PON terminal device comprises a receiver, wherein the receiver comprises a first power splitter, a first director of a first optical signal, a polarization rotator of light, and a coherent receiver, wherein
the first power splitter splits a first transmit signal sent by a transmitting end into a first signal and a second signal according to power, inputs the first signal to the coherent receiver, and inputs the second signal to the first director of the first optical signal, wherein the first transmit signal comprises a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, wherein the first polarized optical signal includes first data;
the first director of the first optical signal is connected to the polarization rotator of light, and the first director of the first optical signal inputs the second signal to the polarization rotator of light;
the polarization rotator of light separately rotates a first polarized optical signal and a second polarized optical signal of the second signal by 90 degrees, and input the rotated second signal to the first director of the first optical signal; and the first director of the first optical signal inputs the rotated second signal to the coherent receiver; and
the coherent receiver performs coherent mixing on the rotated second signal and the first signal to obtain the first data; wherein the first data is downlink data, the first transmit signal is a downlink signal, and the transmitting end is the at least one PON central office device.

### Claim 18

A passive optical network (PON) system, comprising at least one PON terminal device and at least one PON central office device;
wherein the at least one PON terminal device comprises a first transmitter, wherein the first transmitter comprises a signal source, a polarization beam splitter, a modulator, and a polarization beam combiner, wherein
the signal source generates an optical signal, and inputs the optical signal to the polarization beam splitter;
the polarization beam splitter splits the optical signal into a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, inputs the first polarized optical signal to the modulator, and inputs the second polarized optical signal to the polarization beam combiner;
the modulator modulates the first polarized optical signal, loads first data into the first polarized optical signal, and inputs the modulated first polarized optical signal to the polarization beam combiner; and
the polarization beam combiner synthesizes the modulated first polarized optical signal and the second polarized optical signal into a first transmit signal, and transmits the first transmission signal to a receiving end, wherein the first data is uplink data, the first transmit signal is an uplink signal, and the receiving end is the at least one PON central office device;
wherein the at least one PON central office device comprises a receiver, wherein the receiver comprises a first power splitter, a first director of a first optical signal, a polarization rotator of light, and a coherent receiver, wherein
the first power splitter splits a first transmit signal sent by a transmitting end into a first signal and a second signal according to power, inputs the first signal to the coherent receiver, and inputs the second signal to the first director of the first optical signal, wherein the first transmit signal comprises a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, wherein the first polarized optical signal includes the first data;
the first director of the first optical signal is connected to the polarization rotator of light, and the first director of the first optical signal inputs the second signal to the polarization rotator of light;
the polarization rotator of light separately rotates a first polarized optical signal and a second polarized optical signal of the second signal by 90 degrees, and inputs the rotated second signal to the first director of the first optical signal; and the first director of the first optical signal inputs the rotated second signal to the coherent receiver; and
the coherent receiver performs coherent mixing on the rotated second signal and the first signal to obtain the first data, wherein the first data is uplink data, the first transmit signal is an uplink signal, and the transmitting end is a PON terminal device.

### Claim 19

A signal transmission method, comprising:
splitting an optical signal into a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other;
modulating the first polarized optical signal, and loading first data into the first polarized optical signal; and
synthesizing the modulated first polarized optical signal and the second polarized optical signal into a first transmit signal, and transmitting the first transmit signal to a receiving end, wherein the first data is uplink data and the first transmit signal is an uplink signal, or the first data is downlink data and the first transmit signal is a downlink signal.

### Claim 20

A signal receiving method, comprising:
receiving a first transmit signal, wherein the first transmit signal comprises a first polarized optical signal and a second polarized optical signal having polarizations that are perpendicular to each other, wherein the first polarized optical signal includes first data, the first transmit signal is an uplink signal, and the first data is uplink data, or the first transmit signal is a downlink signal and the first data is downlink data;
splitting the first transmit signal into a first signal and a second signal according to power;
separately rotating a first polarized optical signal and a second polarized optical signal of the second signal by 90 degrees; and
performing coherent mixing on the rotated second signal and the first signal to obtain the first data.