Abstract
Selective enhancement () of harmonics extending to the water window () generated in an argon gas filled straight bore capillary waveguide is demonstrated. This enhancement is in good agreement with modeling which indicates that multimode quasi-phase-matching is achieved by rapid axial intensity modulations caused by beating between the fundamental and higher-order capillary modes. Substantial pulse energies ( per pulse per harmonic order) at wavelengths beyond the carbon edge (, ) up to are observed from argon ions for the first time.
- Received 15 February 2007
DOI:https://doi.org/10.1103/PhysRevLett.99.143901
©2007 American Physical Society