Carrier-signal power ratio control in direct detection optical systems

Patent metadata

Field	Value
Publication number	US-9608723-B2
Application number	US-201414518881-A
Country	US
Kind code	B2
Filing date	Oct 20, 2014
Priority date	Oct 20, 2014
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

System and method embodiments are provided for carrier-signal power ratio (CSPR) control in direct detection optical systems. In an embodiment, a method for CSPR control in a direct detection optical system includes receiving an electrical signal in a receiver (RX) digital signal processor (DSP), wherein the electrical signal is obtained from a corresponding optical signal via a direct detection component; estimating, a CSPR for the electrical signal; generating one of a control signal according to the CSPR; and transmitting the control signal to one of an optical filter and a laser, wherein the wavelength control signal controls causes a center wavelength (CW) of one of the optical filter and the laser to be adjusted such that an offset between the CW of the laser and the CW of the optical filter results in a desired CSPR.

First claim

What is claimed is:

1. A method for carrier-signal power ratio (CSPR) control in a direct detection optical system, comprising:
receiving an electrical signal in a receiver (RX) digital signal processor (DSP) wherein the electrical signal is obtained from a corresponding optical signal via a direct detection component;
estimating, with the RX DSP, a CSPR for the electrical signal, wherein the estimating the CSPR comprises estimating the CSPR in a digital domain according to digital samples in a quadrature amplitude modulation (QAM) demodulator;
generating, with the RX DSP, a control signal according to the CSPR; and
transmitting, with the RX DSP, the control signal to a first optical element, wherein the control signal causes a center wavelength (CW) of the first optical element to be adjusted such that an offset between the CW of the first optical element and the CW of a second optical element results in a specified CSPR.

2. The method of claim 1 , wherein the first optical element comprises one of an optical filter and a laser and wherein the second optical element comprises the other one of the optical filter and the laser.

3. The method of claim 1 , wherein data traffic through the system is uninterrupted.

4. The method of claim 1 , wherein estimating the CSPR comprises determining a ratio of signal power and a signal due to signal-signal beat interference (SSBI).

5. The method of claim 1 , wherein estimating the CSPR comprises determining an estimated CSPR, wherein the estimated CSPR comprises a CSPR′, and wherein the CSPR′ is determined according to:

CSPR
′

=

10
⁢

⁢

log
10

⁡

(

∑

n
=

N
⁢

⁢
1

N
⁢

⁢
2

⁢

⁢



ⅆ
n



2

2
⁢

⁢

∑

n
=
1

N
⁢

⁢
1

⁢

⁢



ⅆ
n



2

)

where, n is subcarrier index, dn is training data on an n-th subcarrier, N1 is a number of subcarrier in a gap, and N2 is a total number of subcarriers in gap and data sections.

6. The method of claim 1 , wherein estimating the CSPR comprises determining an estimated CSPR, wherein the estimated CSPR comprises a CSPR′, and wherein the CSPR′ is determined according to:

CSPR
′

=

1

N
avg

⁢

∑

N
avg

⁢

⁢

10
⁢

⁢

log
10

⁡

(

∑

n
=

N
⁢

⁢
1

N
⁢

⁢
2

⁢

⁢



ⅆ
^

⁢
n



2

2

Assignees

• Huawei Tech Co Ltd

Inventors

• Chen Chen
• Li Chuandong
• Zhang Zhuhong

Classifications

• H04J14/0227

  Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation · CPC title

• H04B10/0799

  Monitoring line transmitter or line receiver equipment · CPC title

• H04B10/572

  Wavelength control · CPC title

• H04B10/07955 Primary

  Monitoring or measuring power · CPC title

• H04B10/548

  Phase or frequency modulation · CPC title