Filamantation and White Light Generation with Spatially and Temporally Controlled Femtosecond Radiation

Present laser technology allows the production of ultrashort and intense laser pulses. When matter is exposed to the laser field of such pulses, it exhibits highly nonlinear phenomena that find applications in many fields. Among these phenomena studied in this work are supercontinuum (white light) generation, filamentation, and photodissociation. First we show how the spatial profile of a laser beam can be formed with a phase grating created on a spatial light modulator and then analyzed with a holographic knife-edge method. Then we investigate some possibilities of controlling the nonlinear dynamics of laser-matter interaction by manipulations of the laser field such as creating spatially structured beams, forming high order paraxial beam modes or crossing two femtosecond laser beams in a medium. Additionally, as the first step toward coherent control and manipulation of the interaction of femtosecond radiation with molecular systems, a reconstruction of the momentum fragment distribution of laser-induced photo-dissociation of hydrogen molecular ions produced by 800 nm central wavelength, 50 fs laser pulses was studied experimentally with a time-slicing 3D imaging technique.