To attempt to expand the spectral domain for pulse shortening, we generated several emission lines by stimulated Raman scattering and subsequent four-wave Raman mixing. The efficiency of generation of the Raman emission was improved by passing the beam through two Raman cells that were connected in series. The group-velocity dispersion induced by a Raman cell window and hydrogen was compensated for by means of a pair of chirped mirrors for pulse compression. By a phase lock of the emission lines in the process of four-wave Raman mixing, the pulse width was reduced from 114 to 17 fs in the second Raman cell.
© 2004 Optical Society of America
(140.3550) Lasers and laser optics : Lasers, Raman
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(290.5910) Scattering : Scattering, stimulated Raman
(320.2250) Ultrafast optics : Femtosecond phenomena
Yuichiro Kida, Masahiro Matsuse, Shin-ichi Zaitsu, and Totaro Imasaka, "Generation of a sub-20-fs single optical pulse by four-wave Raman mixing using two Raman cells filled with molecular hydrogen," Opt. Lett. 29, 2809-2811 (2004)