Gregory D. VanWiggeren

CHAOTIC COMMUNICATION USING TIME-DELAYED OPTICAL SYSTEMS

We discuss experimental demonstrations of chaotic communication in several optical systems. In each, an erbium-doped fiber ring laser (EDFRL) produces chaotic fluctuations of light intensity onto which is modulated a message consisting of a sequence of pseudorandom digital bits. This combination of chaos and message propagates at a wavelength of ~ 1.5 microns through standard single-mode optical fiber from the transmitter to a receiver, where the message is recovered from the chaos. We present evidence of the high-dimensional nature of the chaotic waveforms and demonstrate chaotic communications through 35 km of single-mode optical fiber at up to 250 Mbit/s, a rate that is, at present, limited only by the speed of our detector electronics.

Chaotic communication using generalized synchronization

Abstract We present a new technique for the chaotic communication of a signal using the concept of generalized synchronization . We develop a general approach for implementing our technique and illustrate it using a Rossler system driving a Lorenz system. It is demonstrated that the scheme is robust with respect to noise in the communication channel and to small parameter mismatches in the system. Finally, we discuss the advantages of this technique over existing methods and examine ways of improving the scheme.

Transmission of linearly polarized light through a single-mode fiber with random fluctuations of birefringence

A simple theoretical formalism is developed to describe the effect of transmission on linearly polarized light through a fiber with random fluctuations of birefringence. We conclude that, for any optical fiber that does not experience polarization-dependent gain or loss, there exist two orientations for linearly polarized light input into the optical fiber that will also exit the fiber linearly polarized. We report experimental results that verify this prediction and also investigate its practical implications and limitations; in particular we investigate the stability of these linearly polarized output states in laboratory conditions.

Tuning, attenuating, and switching by controlled flexure of long-period fiber gratings

Azimuthal variations in the refractive index that are inherent in CO(2) -laser-induced long-period fiber gratings (LPFGs) coupled to small controlled flexure of the LPFG produce a wide variety of transmission characteristics as a function of LPFG curvature. The particularly useful cases of (1) wavelength tuning at a constant attenuation and (2) variable attenuation (switching) at a constant wavelength are demonstrated by flexing of LPFGs that have been appropriately axially rotationally oriented relative to the plane of curvature.

GENERAL SYNCHRONIZATION OF CHAOS IN A SYSTEM OF TWO NON-IDENTICAL LASERS

General synchronization of the chaotic intensity fluctuations of two spatially coupled Nd:YAG lasers with pump modulation is investigated theoretically when the losses of the two lasers are different. It is shown that the chaotic synchronization still exists for medium coupling even though the two lasers are different. For strong coupling the system shows periodic motion of laser intensities. While for weak coupling, the two lasers oscillate independently. It is obvious that the increase of difference between the two lasers reduces the degree of chaotic synchronization.

Synchronization of Chaos in a Coupled Laser System

Synchronization of the chaotic intensity fluctuations of three pump modulated Nd: YAG lasers oriented in a linear array is investigated both experimentally and numerically. It is shown that synchronization only appears between the two outer lasers with little synchrony between outer and inner lasers. The lack of synchrony between outer and inner lasers is mainly due to the asymmetry of the coupling among the lasers.