System and method for determining fiber characteristics
View Patent ↗A system is provided for characterizing optical fibers carrying signal traffic. The system includes a transmitter, a variable optical attenuator (VOA), a receiver, and a computing device. The transmitter propagates an optical test signal along a channel of a fiber pathway. The VOA adjusts the attenuation of the optical test signal from an initial, greater attenuation to a subsequent, lesser attenuation. At the same time, the computing device monitors at least one other channel of the fiber pathway and identifies effects upon the other channel(s) from the optical test signal. The computing device may communicate with the VOA and with other components of the fiber pathway to direct adjustment of the signal strength. A maximum optical test signal strength may thus be achieved that does not negatively affect signal traffic on the other channels, and the fiber pathway may subsequently be tested using the achieved maximum optical test signal strength.
1. A system, comprising:
an optical fiber pathway;
a transmitter disposed at a first end of the optical fiber pathway and configured to provide an optical test signal for propagation along the optical fiber pathway;
a receiver disposed downstream from the transmitter along the optical fiber pathway and configured to receive the optical test signal that has been propagated along the optical fiber pathway;
a variable optical attenuator disposed between the transmitter and receiver on the optical fiber pathway and configured to attenuate a strength of the optical test signal; and
a computing device communicatively coupled to the transmitter, receiver, and variable optical attenuator and configured to
monitor at least one channel of the optical fiber pathway other than a channel by which the optical test signal is propagated,
identify effects of the optical test signal on the at least one channel, and
direct adjustment of an attenuation level imposed on the optical test signal by the variable optical attenuator.
2. The system of claim 1 , wherein the variable optical attenuator is disposed proximate to the transmitter.
3. The system of claim 1 , further comprising:
optical-to-electrical-to-optical translation components disposed between the transmitter and receiver along the optical fiber pathway and configured to process signal traffic information.
4. The system of claim 1 , further comprising:
a multiplexer disposed between the transmitter and the receiver along the optical fiber pathway and configured to join signals onto channels of the optical fiber pathway; and
a demultiplexer disposed downstream from the multiplexer between the transmitter and receiver and configured to split apart signals from channels of the optical fiber pathway.
5. The system of claim 1 , further comprising:
at leas one optical amplifier disposed between the transmitter and receiver along the optical fiber pathway and configured to amplify optical signals propagated along the optical fiber pathway.
6. The system of claim 1 , further comprising:
at least one optical add/drop module disposed between the transmitter and receiver along the optical fiber pathway and configured to add or drop channels along the optical fiber pathway.
7. The system of claim 1 , further comprising:
a second variable optical attenuator disposed between the transmitter and receiver along the optical fiber pathway in proximity to the receiver and communicatively coupled to the computing device and configured to attenuate the optical test signal to reduce interference between a reflection of the optical test signal caused by the receiver and other signal traffic on other channels of the optical fiber pathway.
8. The system of claim 1 , further comprising:
at least one optical switch disposed between the transmitter and the receiver along the optical fiber pathway and configured to select a channel of the optical fiber pathway by which to propagate the optical test signal.
9. The system of claim 1 , wherein the receiver includes an optical spectrum analyzer configured to analyze a wavelength spectrum of the optical test signal.
10. The system of claim 1 , wherein the receiver includes a polarization mode dispersion analyzer configured to measure a polarization mode dispersion of the optical test signal.
11. The system of claim 1 , further comprising:
a tunable dispersion compensator disposed between the transmitter and receiver along the optical fiber pathway and configured to adjust a dispersion compensation function associated with the optical test signal.
12. A method, comprising:
attenuating, at a first attenuation level, an optical test signal propagating in an optical fiber pathway by a variable optical attenuator;
monitoring at least one channel of the optical fiber pathway other than a channel by which the optical test signal propagates; and
adjusting attenuation of the optical test signal by the variable optical attenuator based on the monitoring of the at least one channel.
13. The method of claim 12 , wherein adjusting attenuation of the optical test signal reduces attenuation of the optical test signal.
14. The method of claim 12 , wherein adjusting attenuation of the optical test signal proceeds until a predefined optical test signal strength is achieved.
15. The method of claim 12 , further comprising:
detecting a predefined alarm condition in the at least one channel of the optical fiber pathway based on the monitoring; and
wherein adjusting attenuation of the optical test signal proceeds until the predefined alarm condition is detected.
16. The method of claim 15 , wherein the predefined alarm condition comprises declination of a signal-to-noise ratio below a threshold level.
17. The method of claim 15 , wherein the predefined alarm condition comprises increase of a bit error rate above a threshold level.
18. The method of claim 15 , further comprising:
selecting a channel of the optical fiber pathway for propagation of the optical test signal.
19. The method of claim 15 , further comprising:
selecting a wavelength of the optical test signal; and
wherein monitoring the at least one channel of the optical fiber pathway comprises measurement of at least one an optical signal-to-noise ratio or pass band shape of the at least one channel.
20. The method of claim 15 , further comprising:
reducing interference between a reflection of the optical test signal and signal traffic on other channels of the optical fiber pathway by attenuating the optical test signal by a second variable optical attenuator disposed in proximity to an optical receiver from which the reflection originates.