Dual wavelenth optical time domain reflectometer systems and methods embedded in a WDM system

• US 9,847,831 B2
• Filed: 04/08/2016
• Issued: 12/19/2017
• Est. Priority Date: 04/08/2016
• Status: Active Grant

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Archambault, Jean-Luc, Boertjes, David W.
• Primary Examiner(s): Payne, David
• Assistant Examiner(s): Ismail, Omar S
• Application Number:
  US15/094,183
• Publication Number:
  US 20170294959A1
• Time in Patent Office: 620 Days
• CPC Class Codes: H04B 10/071 using a reflected signal, e.g. using optical time domain reflectometers [OTDR]
• CPC Class Codes: H04B 10/0775 Performance monitoring and measurement of transmission parameters
• CPC Class Codes: H04J 14/0212 using optical switches or wavelength selective switches [WSS]
• CPC Class Codes: H04Q 11/0062 Network aspects
• CPC Class Codes: H04Q 2011/0083 Testing; Monitoring

Abstract

A dual wavelength Optical Time Domain Reflectometer (OTDR) system, embedded in a network element, includes a first OTDR source for wavelength λ₁; a second OTDR source for wavelength λ₂; an OTDR measurement subsystem adapted to measure backscatter signals λ_{1_BACK}, λ_{2_BACK} associated with the wavelength λ₁ and the wavelength λ₂; and one or more ports connecting the first OTDR source, the second OTDR source, and the OTDR measurement subsystem to one or more fiber pairs; wherein wavelength λ₁ and wavelength λ₂ are each outside of one or more signal bands with traffic-bearing channels, thereby enabling operation in-service with the traffic-bearing channels.

Claims

1. A dual wavelength Optical Time Domain Reflectometer (OTDR) system, embedded in a network element, the dual wavelength OTDR system comprising:

a first OTDR source for wavelength λ

₁;

a second OTDR source for wavelength λ

₂;

an OTDR measurement subsystem adapted to measure backscatter signals λ

_{1_BACK} and λ

_{2_BACK} associated with the wavelength λ

₁ and the wavelength λ

₂; and

one or more ports connecting the first OTDR source, the second OTDR source, and the OTDR measurement subsystem to one or more fiber pairs;

wherein wavelength λ

₁ and wavelength λ

₂ are each outside of one or more signal bands with traffic-bearing channels, thereby enabling operation in-service with the traffic-bearing channels,

wherein the one or more ports connect to a port on a module in the network element, with a single fiber connecting the dual wavelength OTDR to the port on the module, and wherein the module comprises a plurality of optical filters adapted to demultiplex the wavelength λ

₁ and the wavelength λ

₂, to add the wavelength λ

₁ to a first fiber co-propagating with the traffic-bearing channels, and to add the wavelength λ

₂ to a second fiber counter-propagating with the traffic-bearing channels.

2. The dual wavelength OTDR system of claim 1, wherein the OTDR measurement subsystem comprises:

an optical circulator comprising a first port, a second port, and a third port;

an optical filter connected to the first port and adapted to multiplex the first OTDR source and the second OTDR source;

the second port connected to the one or more ports; and

a receiver system connected to the third port.

3. The dual wavelength OTDR system of claim 1, wherein the one or more ports comprise N ports and further comprising:

a 1;

N optical switch connected to the N ports, wherein the 1;

N optical switch is adapted to selectively switch between the N ports to time share the dual wavelength OTDR system.

4. The dual wavelength OTDR system of claim 1, wherein the wavelength λ

₁ is greater than a largest valued wavelength in the one or more signal bands and the wavelength λ

₂ is less than a smallest valued wavelength in the one or more signal bands.

5. The dual wavelength OTDR system of claim 1, wherein the wavelength λ

₁ is greater than a largest valued wavelength in the one or more signal bands to avoid non-linear interactions with the traffic-bearing channels and the wavelength λ

₂ is within a Raman gain bandwidth to monitor Raman gain.

6. The dual wavelength OTDR system of claim 1, further comprising:

a controller communicatively coupled to the OTDR measurement subsystem, wherein the controller is adapted to provide OTDR trace data to an external system.

7. The dual wavelength OTDR system of claim 6, wherein the controller is adapted to

determine a bend loss measurement, and

distinguish between bend loss and a splice or connector loss to detect intrusion on a fiber.

8. The dual wavelength OTDR system of claim 6, wherein the controller is adapted to

determine Raman gain based on the wavelength λ

₁ being in the Raman gain regime and the wavelength λ

₂ being outside the Raman gain regime.

15. The dual wavelength OTDR method of claim 8, further comprising:

providing a controller communicatively coupled to the OTDR measurement subsystem, wherein the controller is adapted to provide OTDR trace data to an external system,

wherein the controller is adapted to

determine Raman gain based on the wavelength λ

₁ being in the Raman gain regime and the wavelength λ

₂ being outside the Raman gain regime.

9. A dual wavelength Optical Time Domain Reflectometer (OTDR) method, wherein the dual wavelength OTDR is embedded in a network element, the dual wavelength OTDR method comprising:

providing a first OTDR source for wavelength λ

₁;

providing a second OTDR source for wavelength λ

₂;

providing an OTDR measurement subsystem adapted to measure backscatter signals λ

_{1_BACK} and λ

_{2_BACK} associated with the wavelength λ

₁ and the wavelength λ

₂; and

providing one or more ports connecting the first OTDR source, the second OTDR source, and the OTDR measurement subsystem to one or more fiber pairs;

wherein wavelength λ

₁ and wavelength λ

₂ are each outside of one or more signal bands with traffic-bearing channels, thereby enabling operation in-service with the traffic-bearing channels,

wherein the one or more ports connect to a port on a module in the network element, with a single fiber connecting the dual wavelength OTDR to the port on the module, and wherein the module comprises a plurality of optical filters adapted to demultiplex the wavelength λ

₁ and the wavelength λ

₂, to add the wavelength λ

₁ to a first fiber co-propagating with the traffic-bearing channels, and to add the wavelength λ

₂ to a second fiber counter-propagating with the traffic-bearing channels.

10. The dual wavelength OTDR method of claim 9, wherein the OTDR measurement subsystem comprises:

an optical circulator comprising a first port, a second port, and a third port;

an optical filter connected to the first port and adapted to multiplex the first OTDR source and the second OTDR source;

the second port connected to the one or more ports; and

a receiver system connected to the third port.

11. The dual wavelength OTDR method of claim 9, wherein the one or more ports comprise N ports and further comprising:

providing a 1;

N optical switch connected to the N ports, wherein the 1;

N optical switch is adapted to selectively switch between the N ports to time share the dual wavelength OTDR system.

12. The dual wavelength OTDR method of claim 9, wherein the wavelength λ

₁ is greater than a largest valued wavelength in the one or more signal bands and the wavelength λ

₂ is less than a smallest valued wavelength in the one or more signal bands.

13. The dual wavelength OTDR method of claim 9, wherein the wavelength λ

₁ is greater than a largest valued wavelength in the one or more signal bands to avoid non-linear interactions with the traffic-bearing channels and the wavelength λ

₂ is within a Raman gain bandwidth to monitor Raman gain.

14. The dual wavelength OTDR method of claim 9, further comprising:

providing a controller communicatively coupled to the OTDR measurement subsystem, wherein the controller is adapted to provide OTDR trace data to an external system,

wherein the controller is adapted to

determine a bend loss measurement, and

distinguish between bend loss and a splice or connector loss to detect intrusion on a fiber.

16. A dual wavelength Optical Time Domain Reflectometer (OTDR) method implemented on an optical fiber with a first wavelength OTDR subsystem communicatively coupled to one end of the optical fiber and a second wavelength OTDR subsystem communicatively coupled to another end of the optical fiber, the dual wavelength OTDR method comprising:

performing a first OTDR measurement on the optical fiber with the first wavelength OTDR subsystem using a wavelength λ

₁; and

performing a second OTDR measurement on the optical fiber with the second wavelength OTDR subsystem using a wavelength λ

₂,

wherein wavelength λ

₁ and wavelength λ

₂ are each outside of one or more signal bands with traffic-bearing channels, thereby enabling operation in-service with the traffic-bearing channels,

wherein each of the first wavelength OTDR subsystem and the second wavelength OTDR subsystem connect to an associated port on an associated module, with a single fiber connecting the each of the first wavelength OTDR subsystem and the second wavelength OTDR subsystem to the associated port on the associated module, and wherein the associated module comprises a plurality of optical filters adapted to demultiplex the wavelength λ

₁ and the wavelength λ

₂, to add the wavelength λ

₁ to a first fiber co-propagating with the traffic-bearing channels, and to add the wavelength λ

₂ to a second fiber counter-propagating with the traffic-bearing channels.

17. The dual wavelength OTDR method of claim 16, wherein the wavelength λ

₁ is greater than a largest valued wavelength in the one or more signal bands and the wavelength λ

₂ is less than a smallest valued wavelength in the one or more signal bands.