Secure wave-division multiplexing telecommunications system and method

Abstract

A fiber optic data transmission system includes an optical fiber and a data transmitter having a first laser having a first wavelength, a first phase modulator for phase modulating light from the first laser as a function of a first data input stream so as to create a first phase-modulated output data stream, a second laser having a second wavelength different from the first wavelength, and a second phase modulator for phase modulating light from the second laser as a function of a second data input stream so as to create a second phase-modulated output data stream. The transmitter also includes a combiner combining the first and second output data streams into a phase-modulated optical signal for transmission over the optical fiber.

What is claimed is:  
     
         1 . A fiber optic data transmission system comprising: 
 an optical fiber; and    a data transmitter having a first laser having a first wavelength, a first phase modulator for phase modulating light from the first laser as a function of a first data input stream so as to create a first phase-modulated output data stream, a second laser having a second wavelength different from the first wavelength, and a second phase modulator for phase modulating light from the second laser as a function of a second data input stream so as to create a second phase-modulated output data stream, the transmitter further including a combiner combining the first and second output data streams into a phase-modulated optical signal for transmission over the optical fiber.    
     
     
         2 . The system as recited in  claim 1  further comprising a controller controlling the first phase modulator as a function of an output of a delayed-feedback exclusive-or gate having the first input data stream as an input.  
     
     
         3 . The system as recited in  claim 2  wherein the controller controls the second phase modulator as a function of another output of another delayed-feedback exclusive-or gate.  
     
     
         4 . The system as recited in  claim 1  further comprising a receiver receiving the phase-modulated optical signal from the optical fiber, the receiver including a splitter for splitting the optical signal into a first path with the first wavelength and a second path with the second wavelength.  
     
     
         5 . The system as recited in  claim 4  wherein the receiver includes a first interferometer receiving the first path and a second intereferometer receiving the second path.  
     
     
         6 . The system as recited in  claim 1  further comprising a detector for detecting a tap or loss of energy in the optical fiber.  
     
     
         7 . A transmitter comprising: 
 a first laser having a first wavelength;    a first phase modulator for phase modulating light from the first laser so as to form a phase-modulated first optical data stream;    a second laser having a second wavelength different from the first wavelength,    a second phase modulator for phase modulating light from the second laser so as to form a phase-modulated second optical data stream,    a combiner for combining the phase-modulated first and second optical data streams, and    a controller controlling the first and second phase modulators as function of a first input electronic data stream and a second input electronic data stream.    
     
     
         8 . The transmitter as recited in  claim 7  wherein the controller includes a first delayed-feedback exclusive-or gate and a second delayed-feedback exclusive-or gate.  
     
     
         9 . The transmitter as recited in  claim 7  further comprising a plurality of further lasers having different wavelengths.  
     
     
         10 . A receiver comprising: 
 an optical splitter for splitting light into a first wavelength and a second wavelength different from the first wavelength, and a first interferometer receiving light at the first wavelength and a second interferometer receiving light at the second wavelength.    
     
     
         11 . The receiver as recited in  claim 10  wherein the optical splitter includes a Bragg grating.  
     
     
         12 . The receiver as recited in  claim 10  further comprising a detector for detecting a tap or loss of energy in the optical fiber.  
     
     
         13 . The receiver as recited in  claim 10  further comprising a plurality of further interferometers.  
     
     
         14 . A method for transmitting secure data is also provided comprising the steps of: 
 transmitting light from a first laser at a data transmitter;    phase modulating light from the first laser at the data transmitter as a function of a first electronic data input stream so as to create a first output data stream, a first binary bit being represented by a first phase and a second binary bit being presentated by a second phase different from the first phase;    transmitting light from a second laser having a wavelength different from the first laser;    phase modulating light from the second laser at the data transmitter as a function of a second electronic data input stream so as to create a second output data stream; and    combining the first and second output data streams.    
     
     
         15 . The method as recited in  claim 14  wherein the phase modulated data is a function of outputs of delayed-feedback exclusive-or gates.  
     
     
         16 . The method as recited in  claim 14  wherein all of the light from the first and second lasers is phase-modulated.  
     
     
         17 . The method as recited in  claim 14  further including receiving the phase-modulated combined optical signal in a receiver, and splitting the combined output signal into a first and second path as a function of wavelength.  
     
     
         18 . The method as recited in  claim 17  further comprising passing each of the first and second paths through an interferometer.  
     
     
         19 . The method as recited in  claim 14  further including monitoring a fiber for intrusion.