This thesis experimentally investigates issues relevant to the use of semiconductor lasers for optical secure communications systems. The motivation behind this work is in exploiting chaotic dynamics to mask a message, transmit the message to a receiver and recover the message.
The method of chaos generation employed in experimentation is using external-cavity semiconductor lasers. Chaos synchronisation properties, an important consideration for secure chaotic communication systems are studied. A demonstration of message encoding and decoding, and a comparison of different receiver configurations is presented. The advantages on system security of selecting the external-cavity length to increase security is discussed. A demonstration of chaotic wavelength division multiplexing is presented.