Ultra wideband chaotic radar and lidar using nonlinear laser dynamics.

摘要

A novel chaotic radar (CRADAR) system utilizing nonlinear laser dynamics is investigated both numerically and experimentally. The proposed CRADAR system has the advantages of high range resolution, unambiguous correlation profile, possibility of secure detection, low probability of intercept, and high electromagnetic compatibility. With an optical injection (OI) scheme, broadband chaotic microwave waveforms and tunable narrowband harmonic microwaves over a broad frequency range can be generated. With an optoelectronic feedback (OEF) scheme, chaotic pulsing, regular pulsing, frequency-locked pulsing, and quasi-periodic pulsing waveforms can be obtained.; Time series, phase portraits, power spectra, and correlation traces of the diverse waveforms generated are presented. The relation between the complexity of the attractor and the correlation property is examined. The correlation dimension and the largest positive Lyapunov exponent of each waveform are calculated. To study the electrical counter-countermeasures capability and the detection ambiguity of the CRADAR system, ambiguity functions of the chaotic waveforms obtained with the OI and OEF schemes are compared. In the cross-ambiguity functions, both schemes demonstrate their excellent capabilities in ECCM. In the auto-ambiguity functions, the OI scheme shows better unambiguous detection quality, where an ideal thumbtack-like ambiguity function is found.; To show the feasibility of the CRADAR system, experiments utilizing a pair of planar antennas are demonstrated. The capability of anti-jamming and the performance under additive white Gaussian noise are studied. A range resolution of 9 cm is achieved, which is currently limited by the detection bandwidths of the antennas used. By having the features of both ultra wideband radar and random signal radar, the CRADAR system is shown to be a promising radar system that both civilian and military applications desire.; Applying this concept to the optical domain, a novel chaotic lidar (CLIDAR) system is also studied. The CLIDAR system that utilizes a chaotic semiconductor laser as the light source possesses the advantages of high resolution, compact, high efficiency, light weight, and low cost. To show the feasibility, experiments including range finding, two-dimensional imaging, and multiple-target detection are demonstrated. A sub-centimeter accuracy in ranging with a 3-cm range resolution is achieved.