Simuation of Masked Communication with Chaotic Lasers

R.M Moraes,J.R.R Leite,L.B O Neto

doi:10.14209/jcis.1997.14

Abstract

This paper describes communication with chaotic laser pulses. An information bearing signal is masked within the chaotic carrier pulses and recovered via chaos synchronization in a chaotic receiver. Two analog circuits, representing chaotic CO2 lasers, simulate the system. The chaotic pulsation from the first circuit was modulated and transmitted to the second one which behaved like a receptor, demodulating the chaotic signal through synchronism. Temporal series give power spectrum and return maps from Poincare section of transmitted signal. In these no trace of modulation is observable, which verifies the masked nature of the sent messages.

Highlights

With out an appropriate synchronizing receiver, a chaotic time se ries would be picked up, but the message will remain buried in the chaos. Within this decade completely new techniques of communi cation exploiting the properties of classical chaotic systems have been pro posed and are under development [1]-[3]
Breaking masked messages transmitted within a chaotic signal, without a synchronizing receiver, is only possible when certain redundancies, contained in the chaotic time se ries, are violated
We present the results of analog circuit simulation of CSK communica tion between two CO2 lasers with saturable absorber

Summary

INTRODUCTION

Within this decade completely new techniques of communi cation exploiting the properties of classical chaotic systems have been pro posed and are under development [1]-[3]. The parameters in the equations are the normalized relaxation rates, saturation coefficients, and pumping rates in the absorber and amplifiers. Detailed explanation of these dimensionless coefficients and the phys ical behaviour contained in the above equations for a single laser are given in Ref. The chaotic pulsation of single mode CO2 laser with an intra cavity saturable absorber (LSA) has been extensively studied [11]. The return maps [14] reconstructed from this chaotic be havior is I-D but with a multibranched structure that accu mulates to an infinity number as one approaches the homo clinic tangency [ll] This was the region of chaos chosen to generate the modulated signal, as described further

ELECTRONIC CIRCUITS

COMMUNICATION

Findings

CONCLUSIONS