System and method for monitoring an optical fiber

• US 20070115456A1
• Filed: 11/23/2005
• Published: 05/24/2007
• Est. Priority Date: 11/23/2005
• Status: Active Grant

• Current Assignee: SBC Knowledge Ventures LP (AT&T, Inc.)
• Original Assignee: SBC Knowledge Ventures LP (AT&T, Inc.)
• Inventors: Wisseman, Philip
• Granted Patent: US 7,310,135 B2
• Time in Patent Office: Days
• US Class Current: 356/73.100
• CPC Class Codes: H04B 10/00 Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication

Abstract

A system and method are disclosed for monitoring a fiber optic network between a managed location and a remote location. In a particular embodiment of the method the monitoring wavelength signal is separated from the communication wavelength signal at the remote location and coupled on to the optical fiber carrying a communication wavelength signal from the remote location. In a particular embodiment of the system, the system includes a first optical filter for coupling a selected monitoring wavelength signal on to an optical fiber carrying a communication wavelength signal between the managed location and the remote location and a second optical filter at the managed location for recovering a permanently separated monitoring wavelength signal sent to the managed location from the remote location.

Claims

1. A method for monitoring an optical fiber between a managed location and a remote location, the method comprising:

receiving concurrently at the remote location from the managed location, a monitoring wavelength signal and a communication wavelength signal over an optical fiber between the managed location and the remote location;

passively separating the monitoring wavelength signal from the communication wavelength signal at the remote location;

passively coupling the separated monitor wavelength signal on to the optical fiber at the remote location; and

sending the separated monitoring wavelength signal over the optical fiber from the remote location to the managed location-for monitoring at the managed location.

2. The method of claim 1, wherein the remote location receives the monitoring wavelength signal over a first optical fiber, receives the communication wavelength signal over a second optical fiber and sends the separated monitoring wavelength signal over the second optical fiber.

3. The method of claim 2, wherein the communication wavelength signal and the monitoring wave length signal are sent in opposite directions.

4. A method for monitoring an optical fiber between a managed location and a remote location, the method comprising:

sending concurrently, from the managed location, a passively coupled monitoring wavelength signal and a communication wavelength signal over an optical fiber between the managed location and the remote location; and

receiving the passively separated monitoring wavelength signal at the managed location from the remote location.

5. The method of claim 4, wherein the passively separated monitoring wavelength signal is passively separated from the communication wavelength signal at the remote location and the passively separated monitor wavelength signal is passively coupled on to the optical fiber at the remote location.

6. The method of claim 4 further comprising:

measuring a transmitted optical power value for the monitoring wavelength signal sent from the managed location and a received optical power value for the passively separated monitoring wavelength signal received at the managed location.

7. The method of claim 6, further comprising:

determining an optical attenuation from a difference between the transmitted optical power value and the received optical power value.

8. The method of claim 4 wherein sending further comprises sending the monitoring wavelength signal over a first optical fiber, sending the communication wavelength signal over a second optical fiber and receiving further comprises receiving the monitor wavelength signal over the second optical fiber.

9. The method of claim 8, wherein sending further comprises sending the monitoring wavelength signal over a plurality of optical fibers including the first optical fiber, in a first transmission direction and sending the communication wavelength signal in a second transmission direction, wherein the second transmission direction is opposite from the first transmission direction.

10. The method of claim 4, wherein the monitor wavelength signal is processed at the managed location by at least one selected from the set consisting of analog modulation, digital modulation, digital modulation with pseudo-random bit sequencing at the communication data rate and locking a wavelength for the monitoring wavelength signal.

11. A system for monitoring an optical fiber between a managed location and a remote location, comprising:

an optical fiber placed between a managed location and a remote location;

a first optical filter for passively separating a monitoring wavelength signal from a communication wavelength signal received concurrently in opposite directions from the managed location at the remote location over the optical fiber; and

a second optical filter at the remote location for passively coupling the separated monitoring wavelength signal on to the optical fiber at the remote location for sending the separated monitoring wavelength signal to the managed location.

12. The system of claim 11, wherein at least one of the set consisting of the first and second optical filters is passive.

13. The system of claim 11, wherein the optical fiber further comprises a first and a second optical fiber, wherein the first optical fiber receives the communication wavelength signal and the second optical fiber sends the separated monitoring wavelength signal.

14. A system for monitoring an optical fiber between a managed location and a remote location, comprising:

a first optical filter for coupling a monitoring wavelength signal on to the optical fiber carrying a communication wavelength signal between the managed location and the remote location using a passive circuit; and

a second optical filter at the managed location for recovering the passively coupled monitoring wavelength signal sent on the optical fiber to the managed location from the remote location.

15. The system of claim 14, further comprising:

a third optical filter at the remote location for passively separating the monitoring wavelength signal from the communication wavelength signal at the remote location; and

a fourth optical filter at the remote location for passively coupling the monitoring wavelength signal on to the optical fiber from the remote location.

16. The system of claim 14 further comprising:

a processor in the managed location;

a computer readable medium accessible to the processor;

a computer program embedded within the computer readable medium, the computer program comprising;

instructions to measure a transmitted optical power value for the monitoring wavelength signal;

instructions to measure a received optical power value for the coupled monitoring wavelength signal; and

instructions to determine an optical attenuation from the transmitted and received optical power values.

17. The system of claim 14, wherein the computer program further comprises instructions to determine an alarm condition based on the optical attenuation.

18. The system of claim 14 further comprising:

a communication port for network access to optical attenuation values.

19. The system of claim 14, wherein the optical fiber further comprises a first and second optical fibers, wherein the first optical fiber is used to send the communication wavelength signal and the second optical fiber is used to receive the monitoring wavelength signal.

20. The system of claim 19, wherein the communication wavelength signal and the monitoring wavelength signal are sent in opposite directions.

21. The system of claim 14, wherein the passive circuit is a filter.