Dual-mode fiber optic telecommunications system and method

• US 6,665,500 B2
• Filed: 01/29/2001
• Issued: 12/16/2003
• Est. Priority Date: 01/29/2001
• Status: Expired due to Term
• 

• Current Assignee: Oyster Optics, LLC
• Original Assignee: Oyster Optics, Inc. (Oyster Optics, LLC)
• Inventors: Snawerdt, Peter
• Primary Examiner(s): Pascal, Leslie
• Assistant Examiner(s): Leung, Christina Y
• Application Number:
  US09/772,018
• Publication Number:
  US 20020101640A1
• Time in Patent Office: 1,051 Days
• Field of Search: 559/180, 559/181, 559/182, 559/183, 559/184, 559/185, 559/186, 559/187, 559/188, 559/110, 398/185, 398/186, 398/188, 398/202, 398/203, 398/204
• US Class Current: 398/185
• CPC Class Codes: H04B 10/548 Phase or frequency modulation
• CPC Class Codes: H04B 10/85 Protection from unauthorised access, e.g. eavesdrop protection

Abstract

An optical data transmitter includes at least one light source, a phase modulator for phase modulating light from the light source, and a controller having an input for receiving an electronic data stream, the controller in a first mode controlling the phase modulator so as to create phase-modulated optical signals in the light as a function of the electronic data stream and the controller in a second alternate mode amplitude-modulating the light as a function of the electronic data stream. A dual-mode receiver, an optical data transmission system and a dual-mode optical signal are also disclosed.

Claims

1. An optical data transmitter comprising:

a laser;

a phase modulator for phase modulating light from the light source; and

a controller having an input for receiving an electronic data stream, the controller in a first mode controlling the phase modulator so as to create phase-modulated optical signals in the light from the laser as a function of the electronic data stream and the controller in a second alternate mode amplitude-modulating the light from the laser as a function of the electronic data stream, the first mode and the second mode occurring at different times.

2. The transmitter as recited in claim 1 wherein the controller in the second mode amplitude modulates the light in direct relation to the input data stream.

3. The transmitter as recited in claim 1 wherein the controller in the second mode amplitude modulates the light as a function of an output of a delayed-feedback exclusive-or gate having the electronic data stream as an input.

4. The transmitter as recited in claim 1 wherein the controller has a switch for switching between the first and second modes.

5. The transmitter as recited in claim 4 wherein the switch is operator-activated.

6. The transmitter as recited in claim 1 wherein the switch is bit-data activated.

7. The transmitter as recited in claim 6 wherein bit data contained in a packet activates the switch.

8. The transmitter as recited in claim 1 wherein the laser is directly adjacent the phase-modulator.

9. The transmitter as recited in claim 1 wherein during the second mode the phase-modulator provides a constant or no phase-modulation change.

10. An optical data transmitter comprising:

a light source;

a phase modulator for phase modulating light from the light source; and

a controller having an input for receiving an electronic data stream, the controller in a first mode controlling the phase modulator so as to create phase-modulated optical signals in the light from the light source as a function of the electronic data stream and the controller in a second alternate mode amplitude-modulating the light from the light source as a function of the electronic data stream;

wherein the controller in the first mode preferably phase-modulates the light as a function of an output of a delayed-feedback exclusive-or gate having the electronic data stream as an input.

11. A receiver for receiving optical signals, the optical signals including both phase-modulated optical signals and direct amplitude-modulated optical signals, the receiver comprising:

an interferometer for reading the phase-modulated signals; and

a detector to read the direct amplitude-modulated optical signals;

wherein the interferometer receives delayed amplitude-modulated optical signals.

12. The receiver as recited in claim 11 further comprising a switch for switching between an output of the interferometer and another output of the detector.

13. The receiver as recited in claim 12 wherein the switch is operator-controlled.

14. The receiver as recited in claim 12 wherein the switch is bit-data controlled.

15. The receiver as recited in claim 11 further comprising an energy level detector for measuring light energy in a fiber.

16. A dual-mode optical transmission system comprising:

a transmitter having a laser for transmitting amplitude-modulated signals in a first mode and phase-modulated signals in a second mode and a controller for switching an output of the laser between the first mode and the second mode, the second mode occurring at a different time than the first mode;

an optical fiber connected to the transmitter; and

a receiver having an interferometer being connected to the optical fiber.

17. A method for transmitting optical data in two modes comprising the steps of:

phase modulating light from a laser during a first transmission mode so as to transmit phase-modulated optical data; and

amplitude modulating light from the laser during a second alternate transmission mode so as to transmit amplitude-modulated optical data, the second alternate transmission mode occurring at a time separate from the first transmission mode.

18. The method as recited in claim 17 wherein during the first transmission mode the light is not amplitude-modulated.

19. The method as recited in claim 17 wherein during the second alternate transmission mode the light is both amplitude-modulated and phase-modulated.