Pulse Shaping

One method used in studies of coherent control is to couple an optical pulse shaping device to a feedback loop that includes an adaptive learning algorithm. Such an apparatus is located in the CAMOS lab. The pulse shaping apparatus takes amplified, stretched, light from the 100 fs laser and disperses it off a grating into separate frequency components. The light is then collimated by a cylindrical lens and passed through a computer controlled liquid crystal array. Using the array, the temporal profile of the pulse is adjusted using phase and sometimes amplitude shaping techniques. The light is then recombined on an identical grating and compressed before being sent to the experiment. Feedback from the experiment allows the adaptive learning algorithm to sort through many possible pulse shapes to locate a particular shape best suited to the experimental problem. To date, most of the work with this apparatus has focused on producing selective fragmentation of small gas phase clusters.