Characterization of ultra-short optical pulses

Thesis (Ph. D.)--University of Rochester. Institute of Optics, 2004.Ultrafast optical pulses are useful probes in many areas of science such as quantum control, chemistry, and micromachining. Knowledge of the pulse shape is central to successful implementation of ultrafast technology and many techniques have been introduced over the years to estimate pulse shapes or completely determine the electric field of the pulse. This thesis investigates and extends the capabilities of one established pulse characterization technique, spectral phase interferometry for direct electric-field reconstruction (SPIDER). Of critical importance to the usefulness of any measurement tool is how well it performs in real laboratory settings. A detailed analysis of how well the SPIDER technique can reconstruct the optical field in the presence of noise, or with limited precision is investigated. In addition, the optimum parameters for the technique in the presence of noise are presented. Space-time coupling is a common phenomenon in ultrafast optics, as both a tool and a hindrance. However, most techniques for measuring ultrafast pulses ignore this effect. We demonstrate for the first time a technique to characterize the complete space-time field of a pulse and use this technique to measure space-time coupling arising from a misaligned grating compressor as well as from propagation of a pulse through a nonlinear material among others. SPIDER can also be modified to have a lower spectral resolution requirement by using spatial, instead of spectral encoding. This allows for a broader pulse bandwidth to fit on a given detector, permitting single shot characterization of shorter pulses than previously accessible by the same detector configuration. The recent advent of attosecond duration pulses has created the opportunity for time-resolved studies of much faster events, such as the motion of electrons in atoms. These pulses, which normally exist in the soft-X-ray (XUV) region of the spectrum, introduce new challenges to short pulse characterization. We outline proposed techniques for measuring XUV pulses of varying durations all based on the nonlinear photoionization process. In addition, a technique for measuring attosecond duration pulses produced by high harmonic generation which avoids photoionization and performs the measurement directly in the XUV is presented