A technique for enhanced generation of high harmonics and attosecond pulses in a gas medium, in a high ionization limit, is described theoretically. An aperiodic corrugated hollow-core waveguide modulates the intensity of the fundamental pulse along the direction of propagation, resulting in quasi-phase-matched harmonic emission at wavelengths close to the cutoff of the spectrum. For a few-cycle laser pulse, linearly chirped corrugation leads to a significant increase of the harmonic yield of a broad frequency band that corresponds to an ∼200-attosecond x-ray pulse. For longer driving pulses, appropriate corrugation permits flexible coherent control of the quasi-phase-matched emission of selected harmonics.
© 2001 Optical Society of America
Ivan P. Christov, "Control of high harmonic and attosecond pulse generation in aperiodic modulated waveguides," J. Opt. Soc. Am. B 18, 1877-1881 (2001)