A femtosecond broadband extreme-ultraviolet quasi-continuum was generated by an intense femtosecond Ti:sapphire laser by two nonlinear optical processes. The first process is the generation of the broadband harmonics by focusing the blueshifted laser pulse through a rare gas. The spectral blueshift is caused by self-phase modulation owing to ionization of the target gas. The second process is the generation of broadband even-order harmonics by the superposition of the second-harmonic electric field upon the fundamental.
© 1998 Optical Society of America
(140.3460) Lasers and laser optics : Lasers
(260.7200) Physical optics : Ultraviolet, extreme
(320.2250) Ultrafast optics : Femtosecond phenomena
(320.7120) Ultrafast optics : Ultrafast phenomena
Taro Sekikawa, Takahito Kumazaki, Yohei Kobayashi, Yasuo Nabekawa, and Shuntaro Watanabe, "Femtosecond extreme-ultraviolet quasi-continuum generation by an intense femtosecond Ti:sapphire laser," J. Opt. Soc. Am. B 15, 1406-1409 (1998)