Propagation of Ultrashort Optical Pulses in Nonlinear Media and Their Applications

In this thesis, nonlinear birefringence in optical fibers has been investigated both experimentally and theoretically. Good agreement has been found between experiment and theory. Its applications in ultrafast optical pulse shaping has been discussed. A more efficient scheme of pulse shaping based on nonlinear birefringence has been proposed and analyzed. It was found that the ellipticity of incident beam can be used to optimize the efficiency of nonlinear transmission. Soliton stability and soliton collisions in birefringent optical fibers were investigated analytically and numerically. A virial theorem for the dynamics of vector temporal solitons was obtained. The nonlinear dependence of the soliton-fusion threshold on the birefringence was obtained for the first time, and was confirmed by computer sin~ulation. The collisions of vector temporal and spatial solitons was studied numerically. It was found that vector soliton collisions can be classified into three different regimes: (i) soliton fusion; (ii) resonant collision; (iii) perturbative regime. The application of collisions of vector solitons in all-optical switching has also been discussed. Finally, the self-defocusing of 1 ps laser pulses in a thin gas target was investigated experimentally. It was found that self-defocusing depends strongly on the focal geometry of the optical system (or 1%). It was found that the intensity profile of laser beam was strongly modified, double foci or cone formation was observed at a pressure of 2 torr. Both the saturation of effective focal shifts and the cone formation are in agreement with theoretical predictions.