Experiments on signal extraction from synchronized chaos in microchip lasers for secure communications

Synchronization of chaos in lasers has attracted great interest because of its potential applications for optical secure communications. Some optical encryption systems using chaos have been proposed; such as chaotic masking, chaos shift keying, and chaotic modulation. Recently, a chaotic masking method using lasers has been experimentally demonstrated, where messages embedded in a chaotic signal were recovered from locally generated chaotic waveforms that precisely synchronize with the original chaotic components. A key part of the chaotic masking method is reproduction of only the original chaos from the transmitted signal with the messages. In this study, we experimentally demonstrate message extraction using the chaotic masking method. We investigate conditions to achieve signal extraction using various microchip laser parameters.