Encoding and decoding messages with chaotic lasers (original) (raw)
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Shannon capacity and codes for communicating with a chaotic laser
IEEE Transactions on Communications, 2002
In this paper, we investigate a method of communicating with chaos described by Hayes, Grebogi, and Ott, which uses the idea of controlling chaos by small perturbations. Although allowing the electronics controlling the output signal to remain at the low-power level, this method unavoidably incurs a capacity loss, which we calculate for a chaotic CO 2 laser model. We first determine an approximation to the laser language, by means of a forbidden set representation, and then find its Shannon capacity. Results indicate that, since the capacity loss is not significant, the tradeoff is worthwhile. Finally, we point to simple finite-state encoders that satisfy the constraints imposed by the language.
Extraction of Signals from Chaotic Laser Data
Physical Review Letters, 1999
Several experimental groups have demonstrated communication with chaotic lasers. We analyze data collected from a message-modulated erbium-doped fiber-ring laser (provided by VanWiggeren and Roy). We show that the transmitted signal is dominated by convolution of the message with the response function of the laser. A simple model based on the topology of the laser allows us to recover a hidden message. While prior estimates indicate that the laser dynamics are high dimensional, we show that only four parameters are required, each of which can be recovered from the transmitted signal alone.
Synchronization of chaotic semiconductor lasers: application to encoded communications
IEEE Photonics Technology Letters, 2000
We present experimental evidence for the synchronization of two semiconductor lasers exhibiting chaotic emission on subnanosecond time scales. The transmitter system consists of a semiconductor laser with weak to moderate coherent optical feedback and therefore exhibits chaotic oscillations. The receiver system is realized by a solitary semiconductor laser in which a fraction of the transmitter signal is coherently injected. We find that for a considerably large parameter range, synchronized receiver output can be achieved. We discuss the physical mechanism and demonstrate that the receiver acts as a chaos pass filter, which reproduces the chaotic fluctuations of the transmitter laser, but suppresses additionally encoded signals. Signal extraction at frequencies of up to 1 GHz has been achieved. Thus we provide a simple and robust optical chaos synchronization system that is promising for the realization of communication by sending signals with chaotic carriers.
Physics Letters, 2008
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Physical Review A, 2000
We present experimental evidence for the synchronization of two semiconductor lasers exhibiting chaotic emission on subnanosecond time scales. The transmitter system consists of a semiconductor laser with weak to moderate coherent optical feedback and therefore exhibits chaotic oscillations. The receiver system is realized by a solitary semiconductor laser in which a fraction of the transmitter signal is coherently injected. We find that for a considerably large parameter range, synchronized receiver output can be achieved. We discuss the physical mechanism and demonstrate that the receiver acts as a chaos pass filter, which reproduces the chaotic fluctuations of the transmitter laser, but suppresses additionally encoded signals. Signal extraction at frequencies of up to 1 GHz has been achieved. Thus we provide a simple and robust optical chaos synchronization system that is promising for the realization of communication by sending signals with chaotic carriers.
Uniqueness of the chaotic attractor of a single-mode laser
Physical Review A, 1994
Measurements on an optically pumped NH3 single-mode laser show three different types of chaotic dynamics, Lorentz-type spiral chaos, period-doubling chaos, and type-III intermittency. Analysis of the measurements shows that the peak-intensity return maps of these three types of dynamics have the same shape, indicating that a unique attractor exists for the laser whose topological structure is independent of laser parameters.
Synchronization properties of chaotic semiconductor lasers and applications to encryption
Comptes Rendus Physique, 2004
We review the main properties of two unidirectionally coupled single-mode semiconductor lasers (master-slave configuration). Our analysis is based on numerical simulations of a rate equations model. The emitter, or master laser, is assumed to be an external-cavity single-mode semiconductor laser subject to optical feedback that operates in a chaotic regime. The receiver, or slave laser, is similar to the emitter but can either operate in a chaotic regime, as the emitter closed loop configuration), or without optical feedback and consequently under CW when it is uncoupled (open loop configuration). This configuration is one of the most simple and useful configuration for chaos based communication systems and data encryption. To cite this article: C.R. Mirasso et al., C. R. Physique 5 (2004). 2004 Académie des sciences. Published by Elsevier SAS. All rights reserved.