Quantcast

Method and system for identifying undesired products of non-linear optical mixing

Imported: 23 Feb '17 | Published: 22 Oct '02

Frank A. McKiel, Jr.

USPTO - Utility Patents

Abstract

An optical communications link including a low-level subcarrier to identify the optical carriers that are contributing to an unwanted mixing product. The subcarrier is added to each of the optical carriers, and then the presence or absence of the subcarrier is detected in the mixing product to identify which optical carriers are contributing towards the generation of the mixing product. The subcarrier will appear in the mixing product if its associated optical carrier is participating in the mixing product. The identified optical carriers that contribute to the mixing product can then diminished in amplitude or shifted in wavelength to reduce the impact of the undesirable signals. Several embodiments are described.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a first embodiment of the invention whereby a controller selectively controls the selective addition of a subcarrier to each optical carrier, the controller controlling a spectrum analyzer coupled to the optical link for determining the presence of the subcarrier in a mixing product as a function of which optical carrier is being modulated with the subcarrier;

FIG. 2 is a block diagram of the second preferred embodiment illustrating a separate subcarrier being added to each of the optical carriers, each subcarrier having a different frequency, whereby a spectrum analyzer analyzes the mixing product to determine the presence of the various subcarriers to determine which optical carriers are contributing toward the mixing product;

FIG. 3 is a block diagram of a third embodiment of the present invention similar to the embodiment of FIG. 2, whereby each of the subcarriers is further modulated with data identifying the optical carrier being modulated by the respective subcarrier; and

FIG. 4 is a block diagram of a fourth embodiment of the present invention whereby a subcarrier generator adds a subcarrier to the various optical carriers according to a predetermined pattern, such as sequentially, whereby the spectrum analyzer detects the presence of the subcarrier in the sensed mixing product in view of the predetermined pattern.

Claims

1. An optical communication link, comprising:

2. The optical communication link specified in claim 1, wherein said analyzing means detects the presence of said subcarrier in said mixing product.

3. The optical communication link specified in claim 2, wherein said analyzing means detects the presence of said subcarrier in said mixing product as a function of which one of said optical carriers is being modulated with said subcarrier.

4. The optical communication link specified in claim 3, wherein said control means controls an amplitude of at least one said optical carriers as a function of the detected presence of said subcarrier in said mixing product.

5. The optical communication link specified in claim 1, wherein said analyzing means comprises a spectrum analyzer.

6. The optical communication link specified in claim 1, wherein said sensing means comprises an optical selective level meter (OSLM).

7. The optical communication link specified in claim 6, wherein said sensing means further comprises a discriminator coupled to said OSLM.

8. A device for controlling a modulator coupled to a transmit end of an optical fiber link and an analyzer coupled to a receive end of the optical fiber link of an optical communications system, comprising:

9. The device of claim 8, the processor further configured to:

10. The device of claim 9, the processor further configured to:

11. The device of claim 8, wherein the mixing product is generated by a number of the plurality of optical carriers beating together to produce one or more spurious wavelengths.

12. The device of claim 8, wherein the analyzer comprises a spectrum analyzer.

13. The device of claim 8, the processor further configured to:

14. A device for controlling a modulator coupled to a transmit end of an optical fiber link and an analyzer coupled to a receive end of the optical fiber link in an optical communications system, comprising:

15. The device of claim 14, the logic circuitry further configured to:

16. The device of claim 14, wherein the analyzer comprises a spectrum analyzer.

17. The device of claim 14, the logic circuitry further configured to:

18. A computer-readable medium containing instructions for controlling at least one processor to perform a method for controlling a modulator and an analyzer in an optical communications system, the method comprising:

19. An optical system coupled to an optical fiber link, comprising:

20. The system of claim 19, wherein the mixing product is generated by a number of the plurality of optical carriers beating together to produce one or more spurious wavelengths.

21. The system of claim 19, wherein the received measurements indicate a presence or absence of the subcarrier in the mixing product.

22. The system of claim 21, the controller further configured to:

23. The device of claim 21, the controller further configured to:

24. The device of claim 19, the controller further configured to:

25. An optical system coupled to an optical fiber link, comprising:

26. The system of claim 25, wherein the mixing product is generated by a number of the plurality of optical carriers beating together to produce one or more spurious wavelengths.

27. The system of claim 25, wherein the received measurements indicate a presence or absence of the subcarrier in the mixing product.

28. The system of claim 27, the controller further configured to:

29. The device of claim 27, the controller further configured to:

30. The device of claim 25, wherein the analyzer comprises a spectrum analyzer.

31. The device of claim 25, the controller further configured to:

32. An optical communications system, comprising: