High order frequency conversion in the plasma waveguide

Summary form only given. We have demonstrated guiding of intensities up to 5/spl times/10/sup 18/ W/cm/sup 2/ in plasma fibers as long as 3 cm. This is well within the range for non-perturbative polarization. Experiments in phase matching and parametric mixing for high-order harmonic generation at high intensity are now being performed using our ability to adjust the waveguide´s length, index depth and curvature, and the laser pulse´s intensity width and wavelength.