Optically modulated chaotic communication scheme with external-cavity length as a key to security

A chaotic optical communication scheme is established using three diode lasers as message, transmitter, and receiver lasers. The message laser is amplitude modulated by a simple message and its output is used to optically modulate the transmitter laser. The transmitter laser is rendered chaotic by application of appropriate optical feedback. The receiver laser is used to decode the message. Effective signal masking is enhanced by the selection of an appropriate external-cavity length, which is proposed as a possible key for security of chaotic optical communication.