Laser Self-Focusing and Nonlinear Absorption in Expanding Clusters

An intense short-pulse laser, propagating through a clustered gas, converts the clusters into hot plasma balls on subpicosecond time scale. The polarizability of a ball scales as (omega pe 2 /3 - omega 2 ) -2 , where omega pe is the plasma frequency inside it and omega is the laser frequency. Initia...

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Bibliographic Details
Published in:IEEE transactions on plasma science 2007-08, Vol.35 (4), p.1089-1097
Main Authors: Chuan Sheng Liu, Parashar, J.
Format: Article
Language:English
Subjects:
Absorption
Atomic clusters
Clusters
Dielectric constant
Dielectric properties
Electromagnetism
Exact sciences and technology
Fluid dynamics
Fluid flow
Frequencies
Frequency
Gas lasers
Hydrodynamics
Lasers
nonlinear absorption
Nonuniform
Optical propagation
Permittivity
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
Plasma
Plasma properties
Plasmas
Polarization
Refractive index
Resonance
self focusing
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Summary:An intense short-pulse laser, propagating through a clustered gas, converts the clusters into hot plasma balls on subpicosecond time scale. The polarizability of a ball scales as (omega pe 2 /3 - omega 2 ) -2 , where omega pe is the plasma frequency inside it and omega is the laser frequency. Initially, omega pe 2 /3 > omega 2 ; however, as the clusters expand under hydrodynamic pressure, decreases, causing resonant enhancement in permittivity, first near the laser axis and later away from it. The nonuniform refractive index profile thus created leads to self-focusing of the laser. It also leads to enhanced absorption in its neighborhood that counters the self-focusing effect substantially.
ISSN:0093-3813
1939-9375
DOI:10.1109/TPS.2007.902126