Chen Wenjian

Chaotic laser synchronization and its application in optical fiber secure communication

In this paper, optical fiber chaotic secure communication is proposed by coupling chaotic laser synchronous system with optical fiber propagation channel. Feedback synchronous system of chaotic semiconductor lasers is presented and synchronous error and decoding formulae are demonstrated. Synchronization between two chaotic laser systems with distributed feedback semiconductor lasers at wavelength of 1.31 µm is simulatively achieved with almost zero synchronous error. Parameter mismatch, synchronous transient response and noise effect on the system are studied. Robustness of synchronization and anti-perturbation can increase by increasing the feedback coefficient of the system. Influence of group-velocity-dispersion and self-phase modulation of optical fiber on chaotic laser signal and synchronization are analyzed, and it is found that group-velocity-dispersion affects pulse shape, synchronization and decoding, and limits optical fiber propagation distances, and self-phase modulation does not affect pulse shape, while its product of nonlinear phase shift can affect synchronization and decoding, and restrict propagation distances of optical fiber chaotic communication system and hence the maximum optical power formula is educed. Injecting parameter modulation and amplitude modulation are numerically simulated in long-haul optical fiber secure communication systems.

Design of Digital Home Remote Monitoring System Based on Web and GPRS

This paper introduces a digital home remote monitoring system based on the technology of Web, image processing, Ethernet correspondence and GPRS wireless communication, presents the structure and work principles of the system, puts emphasis on the mostly hardware and software design of the system. User can realize the online remote supervision, management and maintenance with a standard Web browser over Internet without time-space constraints and some special software. The system has cross-platform compatibility which resolves network access problem effectively making use of finite resource. Practical results demonstrate the system realizes the rapid alarm, remote monitoring function, and has the favorable stability and real time characteristic.