SECURED FIBER LINK SYSTEM

• US 20170244478A1
• Filed: 02/17/2017
• Published: 08/24/2017
• Est. Priority Date: 02/18/2016
• Status: Active Grant

• Current Assignee: Apriori Network Systems, LLC
• Original Assignee: Apriori Network Systems, LLC
• Inventors: WEINER, Gary M.
• Granted Patent: US 10,284,288 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 10/85 Protection from unauthorised access, e.g. eavesdrop protection
• CPC Class Codes: H04L 69/00 Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass networks security protocols H04L9/40; wireless communication networks H04W

Abstract

A fiber link system, method and device for masking signals on a fiber link system. The system includes sending a desired sequence of information in the form of a true signal that is typically intended to be transferred between legitimate users at both ends of a link. Sending chaff signals, or subterfuge signals, alongside the true signal to mask such legitimate signals in the fiber cable from intruders tapping into the fiber cable.

Claims

1. A system secured fiber links, comprising:

a spatially multiplexing optical fiber;

a transmit spatial multiplexer configured to couple a plurality of optical signals into a plurality of spatial paths of the spatially multiplexing optical fiber;

at least one optically modulated transmit source;

at least one optically modulated chaff source; and

a receive spatial multiplexer configured to extract at least one spatial path from the spatially multiplexing fiber.

2. The system of claim 1, wherein the parallel paths carried by the spatially multiplexing optical fiber are nominally uncoupled.

3. The system of claim 1, wherein

the spatial multiplexer comprises lensed fiber based couplers, tapered glass fiber couplers, polymer based couplers, or free space bulk optics couplers, wherein

the optically modulated transmit sources are modulated using any of on-off keying, phase modulation or quadrature amplitude modulation and wherein

the spatially multiplexing fiber is a multi-core fiber.

4. The system of claim 1, configured by at least one of:

at least one of the optically modulated chaff sources occupies substantially the same optical frequency range as at least one of the optically modulated transmit sources,

at least one of the optically modulated chaff sources employs substantially the same optical modulation format as at least one of the optically modulated transmit sources, and

at least one of the optically modulated chaff sources is temporally synchronized with at least one of the optically modulated transmit sources.

5. The system of claim 1, wherein a plurality of optically modulated chaff sources contain data streams.

6. The system of claim 5, wherein the data streams are at least one of:

generated at the chaff transmitter in real time, pre-recorded and stored at the chaff transmitter, and generated at the chaff transmitter using a quantum random number generator.

7. The system of claim 1, wherein the aggregate optical power of all the optically modulated chaff sources within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the ratio of chaff power to transmit signal power coupled out at a fiber bend anywhere along the link is smaller than the required signal-to-noise ratio specified by the transmit signal'"'"'s corresponding receiver to achieve error-free performance at its output.

8. The system of claim 1, wherein the optical powers of at least one optically modulated chaff source within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the ratio of chaff power to transmit signal power coupled out at a fiber bend anywhere along the link is smaller than the required signal-to-noise ratio specified by the transmit signal'"'"'s corresponding receiver to achieve error-free performance at its output.

9. The system of claim 1, wherein the aggregate optical power of all the optically modulated chaff sources within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the chaff optical power coupled out at a fiber bend anywhere along the link is larger than that transmit signal'"'"'s optical power coupled out at a fiber bend at the same point along the link.

10. The system of claim 1, wherein the optical power of at least one optically modulated chaff source within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the chaff optical power coupled out at a fiber bend anywhere along the link is larger than that transmit signal'"'"'s optical power coupled out at a fiber bend at the same point along the link.

11. The system of claim 1, wherein the optical transmit source is provided external to the entity providing the optical chaff sources, wherein the entity providing the optical chaff sources determines the optical frequency range occupied by at least one externally provided optical transmit source, wherein the optical frequency range of the optical chaff sources is adapted to the optical frequency range of the externally provided optical transmit sources, and wherein the power of the optical chaff sources is adapted according to the optical power of the externally provided optical transmit sources.

12. The system of claim 1, wherein a receive spatial multiplexer is configured to extract at least one optical signal from the spatially multiplexing optical fiber, wherein the at least one extracted optical signal are detected locally, and wherein the at least one extracted optical signal is made available as a system output.

13. The system of claim 12, wherein the power of the at least one optical chaff signal and the power of the at least one transmit signal are measured, and wherein the ratio of the measured chaff and transmit signal powers are compared to the ratio of launched chaff and transmit signal powers.

14. A method for securing fiber links, comprising:

coupling a plurality of optical signals into a plurality of spatial paths of a spatially multiplexing optical fiber, wherein there are at least one optically modulated transmit source comprising real data and at least one optically modulated chaff source.

15. The method of claim 14, further comprising:

extracting by a receive spatial multiplexer at least one spatial path from the spatially multiplexing fiber.

16. The method of claim 14, further comprising:

configuring by at least one of;

at least one of the optically modulated chaff sources occupies substantially the same optical frequency range as at least one of the optically modulated transmit sources,

at least one of the optically modulated chaff sources employs substantially the same optical modulation format as at least one of the optically modulated transmit sources, and

at least one of the optically modulated chaff sources is temporally synchronized with at least one of the optically modulated transmit sources.

17. The method of claim 14, wherein the data streams are at least one of:

generated at the chaff transmitter in real time, pre-recorded and stored at the chaff transmitter, and generated at the chaff transmitter using a quantum random number generator.

18. The method of claim 14, wherein the aggregate optical power of all the optically modulated chaff sources within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the ratio of chaff power to transmit signal power coupled out at a fiber bend anywhere along the link is smaller than the required signal-to-noise ratio specified by the transmit signal'"'"'s corresponding receiver to achieve error-free performance at its output.

19. The method of claim 14, wherein the optical powers of at least one optically modulated chaff source within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the ratio of chaff power to transmit signal power coupled out at a fiber bend anywhere along the link is smaller than the required signal-to-noise ratio specified by the transmit signal'"'"'s corresponding receiver to achieve error-free performance at its output.

20. The method of claim 14, wherein the aggregate optical power of all the optically modulated chaff sources within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the chaff optical power coupled out at a fiber bend anywhere along the link is larger than that transmit signal'"'"'s optical power coupled out at a fiber bend at the same point along the link.

21. The method of claim 14, wherein the optical power of at least one optically modulated chaff source within the optical frequency range substantially occupied by an optically modulated transmit source is chosen such that the chaff optical power coupled out at a fiber bend anywhere along the link is larger than that transmit signal'"'"'s optical power coupled out at a fiber bend at the same point along the link.

22. The method of claim 14, wherein the ratio of the measured chaff and transmit signal powers are compared to a ratio of launched chaff power and transmit signal power.

23. The method of claim 22, further comprising:

triggering an alarm when the change of power ratios exceeds a predefined threshold.

24. A fiber terminal, comprising:

an optical coupler for interfacing between at least one individual true signal channel and at least one chaff signal channel and an optical cable link;

a chaff clock synchronizer configured for clock recovery and synchronization;

a chaff signal generator configured to drive the chaff channels in synchronization with the true signal channels; and

at least one transceiver configured to convert between electrical input/output signals and optical signals that are transmitted over the optical cable link.