Influence of wave-front curvature on supercontinuum energy during filamentation of femtosecond laser pulses in water

We demonstrate that using spatially divergent incident femtosecond 1240-nm laser pulses in water leads to an efficient supercontinuum generation in filaments. Optimal conditions were found when the focal plane is placed 100-400 mu m before the water surface. Under sufficiently weak focusing conditions [numerical aperture (NA) < 0.2] and low-energy laser pulses, the supercontinuum energy generated in divergent beams is higher than the supercontinuum energy generated in convergent beams. Analysis by means of the unidirectional pulse propagation equation shows a dramatic difference between filamentation scenarios of divergent and convergent beams, that explains corresponding features of the supercontinuum generation. Under strong focusing conditions (NA >= 0.2) and high-energy laser pulses, the supercontinuum generation is suppressed for convergent beams in contrast to divergent beams that nevertheless are shown experimentally to allow supercontinuum generation. The presented technique of the supercontinuum generation in divergent beams in water is highly demanded in a development of femtosecond optical parametric amplifiers.

NATURVETENSKAP Fysik Atom- och molekylfysik och optik hsv//swe
NATURAL SCIENCES Physical Sciences Atom and Molecular Physics and Optics hsv//eng
group-velocity dispersion
fused-silica
generation
dielectrics
breakdown
light
air
Optics
Physics

Mareev, E. I. (författare)
Smetanina, Evgeniya O.Gothenburg University,Göteborgs universitet,Institutionen för fysik (GU),Department of Physics (GU)(Swepub:gu)xsmeev (författare)
Göteborgs universitetInstitutionen för fysik (GU) (creator_code:org_t)

Av författaren/redakt...: Potemkin, F. V.; Mareev, E. I.; Smetanina, Evgen ...

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