Secure fiber optic telecommunications system and method

CAFC
  • US 6,594,055 B2
  • Filed: 01/17/2001
  • Issued: 07/15/2003
  • Est. Priority Date: 01/17/2001
  • Status: Expired due to Term
First Claim
Patent Images

1. A fiber optic data transmission system comprising:

  • a transmitter having a light source producing light, a phase modulator for phase modulating the light source, and a controller for controlling the phase modulator as a function of an input electronic data stream and a second electronic data stream having a delay, the controller having a controller output electronic data stream of a plurality of bits, each bit being either a binary zero or a binary one, the phase modulator creating a phase-modulated optical signal, for each bit the phase modulator imparting on the light for each binary zero of the controller output electronic data stream either a first phase corresponding to the binary zero or a second phase offset 180 degrees from the first phase corresponding to the binary one so as to create the phase-modulated optical signal, the transmitter having an optical output for the phase-modulated optical signal, the phase-modulated optical signal at the optical output being free of amplitude modulation as a function of the input electronic data stream;

    an optical fiber receiving the optical signal; and

    a receiver receiving the optical signal from the optical fiber, the receiver having a splitter for splitting the optical signal into a first path and a second path, with a path length difference between the first path and second path being a function of the delay in the second electronic data stream.

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