Production, preparation, and performance of shaped ultrafast laser pulses

In the following pages, the current state-of-the art in the method and implementation of acousto-optic modulator (AOM) ultrafast laser pulse shaping is discussed. Since ultrafast laser technologies are relatively recent, many aspects of these pulses and their interaction with material systems (and in particular, optically dense systems) have yet to be well-characterized. Here, we make some headway in understanding the interaction between intense, shaped ultrafast pulses and optically dense media via computer simulations in which the Maxwell-Bloch coupled equations are solved numerically using a recursive algorithm.;In one set of experiments, we studied the propagation of shaped ultrafast laser pulses through a cell filled with an optically dense sample of rubidium vapor. We soon found that the excited state dynamics in atomic rubidium change non-intuitively as different pulse shapes are applied. In this case, characterization of the excited state dynamics is important for illuminating the mechanisms involved in the commercial preparation of the spin-polarized noble gases used in MRI lung studies. Thus, theoretical modeling of the laser- material interaction via the Maxwell-Bloch coupled equations allows us to predict the interaction effects on both the material system and the propagating laser pulses.;In other experiments we show (via computer simulations) that a series of shaped Raman pulses can excite arbitrary vibrational transitions in homonuclear diatomics. In these calculations, a blue-to-red frequency-swept (off-resonant) pump pulse and a red-to-blue Stokes pulse are employed to sequentially excite Delta v = 1 vibrational transitions in an anharmonic potential. Use of increasingly complicated models shows that despite rotational effects, such a pulse sequence should be effective in exciting certain diatomics into high vibrational states. Since highly (vibrationally) excited oxygen is a critical reagent in upper atmosphere energy transfer reactions with nitrogen, its preparation in a laboratory should be useful for studying such processes.;One of the most exciting applications of ultrafast lasers is terabit/second optical communications. In these systems, information is encoded onto ultrafast 1.55 mum laser pulses and transmitted over fiber optic cables. We show that integration of ultrafast pulse shaping methods into existing communications architectures will in many cases increase the possible transition rates. We also define the limits for the density of information that can be encoded onto laser pulses in such systems based upon intrinsic properties of the systems themselves and the Heisenberg Uncertainty Principle.