Generation Of Wide And Flat Broadband Chaotic Laser With Semiconductor Laser Loop

Optical chaotic signals generated from semiconductor lasers with external feedback, or external injection, have been an attractive issue, which have been studied extensively for applications such as chaotic lidar/radar, chaotic correlation optical time domain reflectometer, random number generator and etc.. For these important applications, this thesis carries through some work to enhance the bandwidth of the chaotic laser as follows:1. A scheme for broadband chaotic signal generation using a mutual structure with two laser diodes has been proposed. Numerical results suggest that the scheme has the advantage of generating a flat and adjustable broadband spectrum with the frequency related to the detuning frequency of the semiconductor lasers. In a concept-proof experiment, we showed a broad spectrum of a signal with enhanced bandwidth. The bandwidth can achieve more than 30GHz, which corresponds to the numerical analysis of a dynamical model of the scheme.2. On the basis of the mutual injection structure, the third laser diode is import that forms a laser diode loop. In the experiment, two kinds of oscillation signal were amplified in the laser loop, and generate the 43 GHz flat broadband chaotic signal. For further study, the saturation effect of the oscillation and transmission characteristic is demonstrated. They are the keys of generating broadband chaotic signal. Especially, if more laser diodes were imported, the chaotic signal with broader bandwidth can be obtained.3. The method that applies semiconductor laser loop to generate UWB signal has been proposed the fourth chapter. Changing the strength of the LD1 injection light can make its signal bandwidth switch between two states:43GHz and the vehicular radar bandwidth that Federal Communications Commission defined. The central frequency of the UWB signal is also tunable.