Dual-channel chaotic optical communications using external-cavity semiconductor lasers

We experimentally demonstrate that two chaotic optical communication channels can be configured over a single transmission path by using two external-cavity laser diodes as transmitter lasers and a single stand-alone receiver laser. The two chaotic communication channels are shown to operate independently. Two messages, at different modulation frequencies, generated via direct-current modulation of the transmitter lasers, can be masked by the chaos and recovered at the receiver laser by the use of a decoder laser. The decoder laser is used to select the channel to be utilized. We show that there is good message recovery with little cross talk between the two channels. The channels operate at different laser wavelengths and thus constitute a wavelength-division-multiplexing scheme.