HIGH POWER LASER INTERACTION WITH PLASMAS AND SEMICONDUCTORS

Abstract

The nonlinear interaction of high power laser beam with plasmas and semiconductors have been studied using WKB and method of paraxial ray approximations. In chapter-3, resonant second harmonic generation of a relativistic self-focusing laser under plasma with density ramp profile has been investigated. A high intense Gaussian laser beam produces resonant second harmonic beam in plasma with density ramp profile. The normalized second-harmonic amplitude changes periodically with distance and attains maximum value in the focal region. Enhancement in the second harmonic amplitude on account of relativistic self-focusing of laser based on plasma density transition is seen. Plasma density ramp imparts key role to make self-focusing stronger which leads to enhance the process of second harmonic generation in plasma. newlineIn chapter-4, resonant third harmonic generation of a self-focusing laser beam in plasma with density transition has been investigated. Phase matching is satisfied by wiggler magnetic field which offers the required angular momentum to make the process resonant. Enhancement in the resonant third harmonic generation of a highly intense short pulse laser in plasma under wiggler magnetic field with density transition is seen. Plasma density ramp plays a key role in self-focusing which leads to enhance the third harmonic generation in plasma. We have also examined the effect of wiggler magnetic field on pulse slippage of third harmonic pulse in plasma.In chapter-5, we present the numerical analysis of optimization of wiggler wave number for density transition based second harmonic generation during laser plasma interaction. The wiggler wave number required for phase matching increases with plasma density and the intensity of pump laser beam. It is because of the fact that wiggler magnetic field offers the required angular momentum which is necessary to make the second harmonic generation process resonant. Enhancement in the resonant second harmonic generation of a highly intense ultra-short pulse laser in plasma