Intense XUV and X-Ray Radiation Sources

摘要

In collaboration with Bell Laboratories, we developed a model for the ATIphotoelectron spectra of argon using 200 fs pulses of UV (308nm), radiation. These spectra provide the first identification of ATI from levels which are Stark shifted by values significantly different from the free electron ponderomotive shifts. Using this model, we were able to show the consistency of the photoelectron spectra with spectra obtained elsewhere which indicated substantial residual population of excited states following ATI ionization. We also investigated the ATI of N2 and were the first group to understand this process in detail in a diatomic molecule. At the Univ of Maryland, our work on the first ever channeling of intense laser pulses, demonstrated in the late 1993, continued with the discovery that the intense light propagates as waveguide modes (i.e., we actually observe electromagnetic propagation eigenmodes) at intensities more than 10(exp 8) times beyond the destruction limit of a regular silica based optical fibre. That is, we demonstrated control the dynamically evolving waveguide to provide single mode (near Gaussian) or multimode propagation. We also showed that the guide mode structure is independent of the wavelength of light propagating in it.