Secured fiber link system

A method for securing communication over an optical fiber, comprising:

• supplying an optically modulated version of a desired sequence of information that is intended to be transferred over a multicore optical fiber to a first core of the multicore optical fiber;
• and
• supplying an unmodulated optical chaff signal to a second core of the multicore optical fiber that is spatially distinct from the first core;
• wherein the multicore optical fiber is adapted to transport the unmodulated optical chaff signal from a first end of the multicore optical fiber to a second end of the multicore optical fiber unmodified in the second core;
• wherein the multicore optical fiber is adapted to transport the optically modulated version of the desired sequence of information from the first end of the multicore optical fiber to the second end of the multicore optical fiber unmodified in the first core and independent of the unmodulated optical chaff signal in the second core unless there is a tap of the multicore optical fiber;
• wherein at a tap formed at any location along the multicore optical fiber a signal-to-noise ratio is less than a required signal-to-noise ratio for a receiver at the tap location to achieve substantially error-free recovery of the desired sequence of information,
• wherein noise in the signal-to-noise ratio is a combination of optical power, within an optical frequency range substantially occupied by the optically modulated version of the desired sequence of information, of the unmodulated optical chaff signal and any other one or more optical chaff signals that are coupled to any further cores of the multicore optical fiber beyond the first and second core;
• and
• wherein signal in the signal-to-noise ratio is an optical power of the optically modulated version of the desired sequence of information.

A method for securing communication over an optical fiber, comprising:

• supplying an optically modulated version of a desired sequence of information that is intended to be transferred over a multicore optical fiber to a first core of the multicore optical fiber;
• and
• supplying an unmodulated optical chaff signal to a second core of the multicore optical fiber that is spatially distinct from the first core;
• wherein the multicore optical fiber is adapted to transport the unmodulated optical chaff signal from a first end of the multicore optical fiber to a second end of the multicore optical fiber unmodified in the second core;
• wherein the multicore optical fiber is adapted to transport the optically modulated version of the desired sequence of information from the first end of the multicore optical fiber to the second end of the multicore optical fiber unmodified in the first core and independent of the unmodulated optical chaff signal in the second core unless there is a tap of the multicore optical fiber;
• wherein at a tap formed at any location along the multicore optical fiber a signal-to-noise ratio is less than a theoretically minimum required signal-to-noise ratio for any receiver at the tap location to achieve substantially error-free recovery of the desired sequence of information,
• wherein noise in the signal-to-noise ratio is a combination of optical power, within an optical frequency range substantially occupied by the optically modulated version of the desired sequence of information, of the unmodulated optical chaff signal and any other one or more optical chaff signals that are coupled to any further cores of the multicore optical fiber beyond the first and second core;
• and
• wherein signal in the signal-to-noise ratio is an optical power of the optically modulated version of the desired sequence of information.