Optical transmission system implementing encrypting by deterministic chaos

• US 6,018,582 A
• Filed: 01/03/1997
• Issued: 01/25/2000
• Est. Priority Date: 01/05/1996
• Status: Expired due to Fees

• Current Assignee: Orange S.A.
• Original Assignee: Orange S.A.
• Inventors: Porte, Henri, Francois, Pierre-Luc, Goedgebuer, Jean-Pierre, Larger, Laurent
• Primary Examiner(s): Hayes, Gail O.
• Assistant Examiner(s): SONG, HOSUK
• Application Number:
  US08/779,257
• Time in Patent Office: 1,117 Days
• Field of Search: 380/48, 380/49, 380/21, 364/713, 364/717, 395/200.66, 382/249, 382/209, 382/233, 356/5.01, 356/73, 235/472, 385/133, 385/33, 89/1.11, 359/154
• US Class Current: 380/256
• CPC Class Codes: H04B 10/85 Protection from unauthorised access, e.g. eavesdrop protection
• CPC Class Codes: H04K 1/025 using an analogue chaotic signal
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 9/001 using chaotic signals
• CPC Class Codes: H04L 9/12 Transmitting and receiving encryption devices synchronised or initially set up in a particular manner

Abstract

The invention relates to an optical transmission system that implements encrypting of an information carrying signal by deterministic chaos. The system includes a transmitter (1), a receiver (4), and one transmission channel coupled between the transmitter (1) and the receiver (4). The transmitter (1) includes a deterministic chaos generator (3) coupled to an encoding system (2). The deterministic chaos generator (3) includes a wavelength tunable laser-emitting diode (33) and a feedback loop (34). The active layer of laser diode (33) is offset controlled by a laser signal passed through a non-linear optical element (32) and a delay line (31). The receiver (4) has a deterministic chaos generator (7) coupled to a synchronizer (6) and a decoder coupled to the synchronizer (6). Preferably, chaos generator (3) is the same as chaos generator (7). Other features are disclosed.

Claims

1. A system for transmitting an optical signal carrying information, the system comprising:

transmitter means (1) for emitting an encrypted optical signal, said means comprising means (3) for generating deterministic chaos and means (2) for encoding the information carrying signal by said deterministic chaos;

a line (F) for conveying the signal encrypted in this way; and

receiver means (4) comprising means (7) for generating deterministic chaos, and means (5,

     6) for synchronizing said chaos with the received encrypted signal and for decrypting said encrypted signal;

wherein the chaos is wavelength chaos, the means (3,

     7) for generating chaos including a wavelength tunable light source (33) and a feedback loop (34) for feeding the light signal output by said source back to the wavelength tuning control, said loop (34) including means (32) for non-linear wavelength conversion, and a delay line (31).

2. The system of claim 1, wherein the light source (33) is one of

(i) controlled by an electrical parameter where feedback loop (34) is optoelectronic, and

(ii) optical where feedback loon (34) is optical.

3. The system of claim 2, wherein the non-linear means (32) is an optical element having extrema as a function of wavelength, wherein the optical element is at least one of a two-wave interferometer, a Mach-Zender interferometer, a Fabry-Perot interferometer, a birefringenet crystal, and a multiple wavelength interferometer.

4. The system of claim 1, wherein the encoding means includes means (37) for mixing the information-carrying signal with the signal propagating in the feedback loop (34) to produce chaos λ

_s (t) containing the signal to be transmitted.

5. The system of claim 1, wherein the encoding means (2) includes a phase modulator adapted to phase modulate the emitted wavelength chaos by the information-carrying signal.

6. The system of claim 4, wherein the transmitter means for generating chaos (3) and receiver means for generating chaos (7) are identical.

7. The system of claim 2, wherein both the transmitter means and receiver means include means for modifying the parameters of the feedback loop (34), thereby modifying the encrypting key, wherein the means for modifying the parameters of the feedback loop (34) includes at least one of (i) means for modifying the non-linearity of the conversion means and (ii) means for modifying the value of the delay.

8. The system of claim 1, further comprising:

an encrypting control unit (8) including a key switch (10) coupled to the means (2) for encoding the information carrying signal and a wavelength switch (9) coupled to the means (3) for generating deterministic chaos.

9. A communication device for a transmission system, comprising:

wavelength chaos generator means, said means including a wavelength tunable light source having a light signal and a wavelength tuning control electrode; and

a loop for feedback of the light signal output by said source to the wavelength tuning control electrode, said loop including non-linear conversion means for the wavelength coupled to a delay line.

10. An optical transmission system implementing encrypting of an information carrying signal by deterministic chaos, the system comprising:

a transmitter (1) having a deterministic chaos generator (3) coupled to an encoding system (2), the deterministic chaos generator (3) including a wavelength tunable laser-emitting diode (33) and an opto-electronic feedback loop (34), the wavelength tunable laser-emitting diode (33) having a first electrode for active layer control, a second electrode, a first output for outputting a chaotic signal having a wavelength λ

_s (t), and a second output, the opto-electronic feedback loop (34) having an optical element (32) coupled to the second output of the wavelength tunable laser-emitting diode (33) and a delay line (31) coupled between the optical element (32) and a second electrode of the wavelength tunable laser-emitting diode (33) as wavelength offset control;

a receiver (4) having a deterministic chaos generator (7) coupled to a synchronizer (6) and a decoder coupled to the synchronizer (6); and

one transmission channel coupled between the transmitter (1) and the synchronizer (6) of the receiver (4).

11. The system of claim 10, wherein the one transmission channel is a high speed transmission channel.

12. The system of claim 11, wherein the one transmission channel is a fiber optic cable.

13. The system of claim 10, wherein the deterministic chaos generator (3) and the deterministic chaos generator (7) include the same structure.

14. A method for transmitting a data-carrying signal s(t) encrypted by deterministic chaos as coding noise, the method comprising:

generating a chaotic signal in a chaos generator (3), the chaotic signal having a wavelength λ

₂ (t) that demonstrates chaotic dynamic behavior that is locally deterministic in time;

mixing the data-carrying signal s(t) with the wavelength chaotic signal in an encoding system (2) coupled to the deterministic chaos generator (3) to produce a mixed signal having transmitted chaos;

transmitting the mixed signal over one transmission channel coupled to the transmitter (1);

receiving the mixed signal from the one transmission channel at a receiver (4) having receiving chaos generated in a chaos generator (7);

synchronizing receiving chaos with transmitted chaos at a synchronizer (6) coupled to chaos generator (7); and

decoding the mixed signal at a decoder (5) coupled to the synchronizer (6).

15. The method of claim 14, wherein the chaotic signal presents a white noise frequency spectrum having a frequency band that ranges between 100 Mbit/s and 10 Gbit/s.