In-service optical signal to noise ratio monitoring in an optical network

Patent metadata

Field	Value
Publication number	US-9306664-B1
Application number	US-201314137079-A
Country	US
Kind code	B1
Filing date	Dec 20, 2013
Priority date	Mar 14, 2013
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Methods, mediums and systems described herein determine real-time in-service OSNR measurement without disrupting or turning off one or more channels of the network. An OSNR monitor described herein may be integrated with existing optical line systems. The OSNR measurements performed by the OSNR monitors are independent of the modulation format and thus, may work with all phase formats, amplitude format or a combination thereof. The real-time in-service OSNR data may be used to perform global network optimization to determine the optimal routing and data rate in the optical network. The OSNR data may be used to establish protection and restoration paths for network resiliency and to maximize data throughput.

First claim

The invention claimed is:

1. In an optical network, a method comprising:
tapping off a portion of an optical signal without affecting service in the optical network;
filtering the portion of the optical signal with an optical filter to select a channel in the signal;
passing the filtered signal to a delay line interferometer (DLI);
comparing power at a constructive interference output port of the DLI with power at a destructive interference output port to calculate an optical signal to noise ratio (OSNR) for the channel;
calculating the OSNR for the channel using the power at the constructive interference output port of the DLI and the power at the destructive interference output port of the DLI; and
calibrating the calculated OSNR based on a filter profile of the optical filter.

2. The method of claim 1 , wherein the optical filter is tunable.

3. The method of claim 1 , wherein the DLI is tunable.

4. The method of claim 1 , wherein the OSNR is calculated by an OSNR monitor integrated into optical terminal equipment in the optical network.

5. The method of claim 4 , wherein the OSNR monitor is compatible with a plurality of different optical networks.

6. The method of claim 1 , wherein the calculated OSNR is independent of a wavelength grid spacing of the channel.

7. The method of claim 1 , wherein
calibrating the calculated OSNR includes integrating the filter profile of the optical filter over a passband of the optical filter.

8. In an optical network, a method, comprising:
measuring an optical signal to noise ratio (OSNR) for a channel of an optical signal for a link using an optical filter and a delay line interferometer;
reporting the measured OSNR for the link to a network management tool;
with the network management tool, using the measured OSNR to manage the optical network;
wherein the measured OSNR is calibrated based on a filter profile of the optical filter.

9. The method of claim 8 , wherein the method further comprises using the measured OSNR to determine what data rate the link can support.

10. The method of claim 8 , wherein the method further comprises using the measured OSNR to control at least one of provisioning, traffic engineering or failure protection in the optical network.

11. A monitor for measuring an optical signal to noise ratio (OSNR) in an optical signal in an optical network, the monitor comprising:
an optical filter configured to filter a portion of an optical signal to select a channel in the optical signal without affecting service in the optical network;
a delay-line interferometer (DLI) configured to measure the OSNR in the optical signal, wherein the DLI includes:
a constructive interference output port, and
a destructive interference output port, and

an OSNR calculation unit configured to calculate the OSNR for the channel using power at the constructive interference output port of the DLI and power at the destructive interference output port of the DLI;
wherein the OSNR calculation unit is further configured to calibrate the calculated OSNR based on a filter profile of the optical filter.

12. The monitor of claim 11 , wherein the optical filter is tunable.

13. The monitor of claim 11 , wherein the DLI is tunable.

14. The monitor of claim 11 , wherein the monitor is integrated into optical terminal equipment in the optical network.

15. The monitor of claim 11 , wherein the monitor is compatible with a plurality of difference optical networks.

16. The monitor of claim 11 , wherein the calculated OSNR is independent of a wavelength grid spacing of the channel.

17. The monitor of claim 11 , wherein the OSNR calculation unit is further configured to integrate the filter profile of the optical filter over a passband of the optical filter.

18. The monitor of claim 11 , further comprising:
a first photodetector coupled to the constructive output port of the DLI; and
a second photodetector coupled to the destructive output port of the DLI; wherein the first photodetector and the second photodetector are configured to convert the optical signals to electrical signals.

19. The monitor of claim 11 , wherein:
the optical signal includes a signal component and a noise component,
the signal component is output on both the constructive output port of the DLI and the destructive port of the DLI, and
the noise component is split equally between the constructive output port of the DLI and the destructive port of the DLI.

20. The monitor of claim 11 , wherein the channel to be filtered is selected based on a center frequency of the optical filter.

Assignees

• Google Inc

Inventors

• Vusirikala Vijay
• Zhao Xiaoxue
• Koley Bikash

Classifications

• H04B10/07953 Primary

  Monitoring or measuring OSNR, BER or Q · CPC title