Claims
- 1. A method of compensating for spectral power tilt in an optical fiber connected to an inline optical amplifier comprising the steps of:
reading and storing a first power value of the inline amplifier; reading and storing a second power value of the inline amplifier; comparing the first power value and the second power value to arrive at a difference value; multiplying the difference value by a predetermined constant; and, adjusting a tilt controller to compensate for the spectral power tilt.
- 2. The method of claim 1 wherein the first power value and second power value are inline amplifier output powers.
- 3. The method of claim 1 wherein the first power value and second power value are inline amplifier input powers.
- 4. The method of claim 1 wherein the tilt controller is a two stage EDFA.
- 5. The method of claim 1 wherein the tilt controller includes a variable optical attenuator.
- 6. The method of claim 1 wherein the tilt controller is a tunable filter.
- 7. The method of claim 1 wherein the tilt controller includes a dynamic gain equalizer.
- 8. The method of claim 1 wherein the tilt controller is a tunable optical filter.
- 9. The method of claim 1 wherein the predetermined constant is negative.
- 10. The method of claim 1 wherein the inline amplifier includes a first stage and a second stage separated by a variable optical attenuator.
- 11. The method of claim 10 wherein the step of adjusting further comprises reducing the gain of the second stage by a value proportional to the difference value.
- 12. The method of claim 10 wherein the step of adjusting further comprises reducing the variable optical attenuator output by a second value proportional to the difference value.
- 13. The method of claim 1 including the additional step of:
comparing the difference value to a predetermined threshold value and proceeding to the step of multiplying if the difference value exceeds a predetermined difference value.
- 14. The method of claim 13 wherein the step of reading a second power value is repeated if the difference in value does not exceed a predetermined value.
- 15. The method of claim 13 wherein the predetermined threshold value is about 5 mW.
- 16. The method of claim 13 wherein the predetermined threshold value is about 20 μW.
- 17. The method of claim 1 wherein the predetermined constant reflects the fiber type.
- 18. The method of claim 1 wherein the predetermined constant is an average negative value of about 8 dB/W.
- 19. The method of claim 1 wherein the predefined constant reflects fiber characteristics.
- 20. A system for compensating for spectral power tilt in an optical fiber comprising:
an optical amplifier connected to the fiber; a controller connected to the amplifier; and, the controller programmed to cyclically update the gain tilt of the amplifier in order to compensate for spectral power tilt.
- 21. The system of claim 20 wherein the cyclic update takes place about once in 100 μs.
- 22. The system of claim 20 wherein the amplifier comprises:
a first stage EDFA and a second stage EDFA; and, the system further comprises a variable optical attenuator connected to the second stage of the EDFA and to the controller.
- 23. The system of claim 22 wherein the controller is programmed to perform the following steps:
read a first output power of the second stage EDFA; read a second later output power of the second stage EDFA; compare the first output power with the second later output power to arrive at a difference value; compare the difference value to a predetermined threshold value and if the difference value exceeds the threshold value then adjusting the gain of second stage EDFA to compensate for spectral power tilt.
- 24. The system of claim 23 wherein the threshold value is approximately 5 mW.
- 25. The system of claim 23 wherein the step of adjusting includes reducing the variable optical attenuator by an amount proportional to the difference value.
- 26. The system of claim 25 wherein the amount is multiplied by a negative constant value.
- 27. The system of claim 26 wherein the constant value is related to fiber type.
- 28. The system of claim 1 wherein the constant value is about 8 dB/W.
- 29. A system for compensating for spectral power tilt in an optical fiber comprising:
an optical amplifier connected to the fiber; a logic controller connected to the amplifier; a tilt controller connected to the amplifier; and the logic controller programmed to cyclicly check the optical amplifier power and to alter settings of the tilt controller to compensate for spectral power tilt if the amplifier power changes by a predetermined amount.
- 30. The system of claim 29 wherein the tilt controller is a second stage of the optical amplifier.
- 31. the system of claim 29 wherein the tilt controller includes a dynamic gain equalizer and the logic controller is programmed to alter the settings of the equalizer by changing the loss of the equalizer on a channel-by-channel basis.
- 32. The system of claim 29 wherein the tilt controller is a variable optical attenuator.
- 33. The system of claim 29 wherein the tilt controller is a tunable filter.
- 34. The system of claim 29 wherein the amplifier power is an output power of the amplifier.
- 35. The system of claim 29 wherein the amplifier power is an input power of the amplifier.
- 36. The system of claim 29 wherein the predetermined amount is about 5 mW.
- 37. The system of claim 29 wherein the predetermined amount is about 8 μW.
- 38. The system of claim 29 wherein the controller is programmed to compensate by a value of delta tilt where:
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Provisional Application Serial No. 60/377,084, entitled “Compensation for Spectral Power Tilt from Stimulated Raman Scattering”, by Eiselt, filed Apr. 30, 2002.
Provisional Applications (1)
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Number |
Date |
Country |
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60377084 |
Apr 2002 |
US |