The generation of white-light continuum by femtosecond laser pulses in transparent condensed media is investigated comprehensively with 262-, 393-, and 785-nm pump wavelengths. We find that the ratio of the medium’s bandgap energy to the photon energy of the incident wavelength determines the amount of anti-Stokes broadening, independently of the pump wavelength and the medium’s bandgap. It is also shown that, although the amount of anti-Stokes broadening is greater for the longer pump wavelength, the shorter pump wavelength is more advantageous for generating shorter-wavelength continua in the UV region. In addition, a self-induced change in polarization of the white-light continuum that is generated is observed in an isotropic material with a cubic crystal structure, such as CaF2 and LiF. After the investigation of polarization, the frequency chirp of the continuum is characterized by the Kerr-gate method with 70-fs temporal and 10-nm wavelength resolution.
© 2002 Optical Society of America
[Optical Society of America ]
Chihiro Nagura, Akira Suda, Hiroyuki Kawano, Minoru Obara, and Katsumi Midorikawa, "Generation and Characterization of Ultrafast White-Light Continuum in Condensed Media," Appl. Opt. 41, 3735-3742 (2002)