Generation of Coherent Soft-X-Ray Radiation Extending Far Beyond the Titanium<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>L</mml:mi></mml:math>Edge

Abstract

Coherent soft-x-ray radiation up to photon energies of 700 eV is obtained by focusing several-mJ, 10-fs near infrared laser pulses into a He gas jet. The observed nearly constant photon yield over several hundred eVs may be attributed to nonadiabatic self-phase matching, originating from a substantial ionization within a fraction of the optical cycle of the driving laser pulse.