Generation And Application In Remote Sensing Of Chaos

As the noise-like behavior and good autocorrelation performance, chaotic signal is an ideal signal in communication and radar system. Broadband chaotic laser with band width of10GHz is achieved easily using semiconductor laser. And the chaotic laser can combine with the radio over fiber link very well, for realizing the remote control of sensors to compensate the drawback of the signals’short coverage radius. This dissertation studied the generation and application in remote sensing of chaotic signal. And the main researched contents are as follows:1. We demonstrate a method to generate aperiodic broadband chaotic laser with3dB band width up to13.6GHz experimentally. Aperiodic broadband chaos is achieved by external continuous optical injection and self-injection of back scattering light, combined with self-interference. The nonperiodicity of generated chaotic signal is confirmed according to autocorrelation function.2. An ultra-wideband (UWB) radar system for remote ranging based on microwave-photonic chaotic signal generation and fiber-optic distribution is proposed and demonstrated experimentally. In this system, an optical-feedback semiconductor laser with optical injection in central office generates photonic UWB chaos as probing signal, and two single-mode fibers transport the optical signal to remote antenna monitoring terminal and return the corresponding echoed signal back to the central office. In the remote antenna terminal, the photonic signal is transformed into microwave chaos by a fast photodetector and then launched to target by a transmitting antenna, and the echoed signal received by another antenna is converted into optical domain by modulating a laser diode. The target ranging is achieved at the central office by correlating the echoed signal with reference signal. We experimentally realize a detection range of8m for a free-space target after24km remote distance, and achieve a ranging resolution of3cm for single target and8cm for double targets. This radar system that combines the UWB-over-fiber technology with chaos ranging, not only implements the antenna remote control but also gains a high ranging resolution.3. A microwave-photonic sensor for remote water-level monitoring based on chaotic laser is pro-posed and demonstrated. The probe chaotic signal with bandwidth of18GHz is generated in the central office and then transmitted at the remote antenna unit after a24km single-mode fiber transmission. And the monitoring data from the remote antenna unit is sent back to the center office over fiber. The water-level measuring is accomplished by cross correlation between reference signal and probe signal at the central office. So the remote water-level monitoring system with a high spatial resolution of2cm is achieved and the height of water surface can be displayed in real time.