Pulse shortening of the backscatter of a KrF excimer laser beam focused on the surface of n-hexane is reported. Simultaneous measurements of the backscattered beam, a Fresnel reflected beam, incoherent scattered photons from a liquid surface, and a transmitted beam are performed. The results show that the surface reflected beam disappears followed by beam expansion and the transmitted beam is reduced to form a filamentlike structure with the onset of backscatter. The pulse width of the backscattered beam shows a clear dependence on the focal position in the liquid. Incoherent scattering is sharply enhanced when the laser beam is focused at the liquid surface where the backscattered beam is especially short. The observed phenomena indicate that stimulated thermal scattering is the pulse shortening mechanism.
© 1997 Optical Society of America
Original Manuscript: June 18, 1996
Revised Manuscript: December 5, 1996
Published: October 20, 1997
Takashi Yagi, Kenji Matsubarra, Masafumi Yamashita, and Toshiharu Tako, "Krypton fluoride laser pulse shortening by stimulated thermal scattering on a liquid surface," Appl. Opt. 36, 8002-8009 (1997)