High Intensity Femtosecond Enhancement

To produce extreme ultraviolet radiation via high harmonic generation (HHG) in rare gases, light intensities in excess of 1014 W/cm 2 are required. Usually such high intensity are obtained by parametric amplification of laser pulses, which in turn reduces the pulse repetition rate to a few kHz. Given that the HHG process is inherently inefficient, with conversion ratios less than 10-5, only a small fraction of the pulse energy is lost in the nonlinear interactions, so it is possible to enhance the pulse intensity in a passive cavity retaining the original repetition rate. I present here a novel broadband resonator design which has the potential of supporting intracavity intensities in excess of 1015 W/cm 2 while allowing the harmonic radiation to couple out of the cavity with no loss. Extensive computer simulations are performed with a custom software package, and the required mirrors have been constructed using a standard microfabrication process. Thesis Supervisor: Franz X. Kdrtner Title: Professor of Electrical Engineering