Optical Chaos Masking of Video Signals

Abstract—In this letter, we report on what we believe is the first
demonstration of a cryptographic technique, based on optical
chaos, applied to “real world” high-frequency signals. A standard
TV signal at 2.4 GHz has been transmitted through an optical
fiber link. The output from a chaotic laser, added to the signal
at the transmitter side, strongly reduces its signal-to-noise ratio,
and prevents an eavesdropper tapping the fiber from decoding the
message. At the receiver side, the signal is extracted from chaos
using a master–slave synchronization scheme. This requires a pair
of lasers with strictly matched parameters, which represent the
hardware cryptographic key of the method.