Semiclassical approaches to below-threshold harmonics
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803-4001 (United States)
We study the generation of below-threshold harmonics in a model atom by extending the three-step semiclassical model of harmonic generation to include effects of the atomic potential. We explore the generalization of semiclassical trajectories of the electron in the presence of the combined laser-atom potential and calculate the intensity-dependent dipole phase associated with these trajectories. Our results are in good agreement with fully quantum mechanical calculations, as well as with recent experimental observations. We show that the so-called long trajectory readily generalizes to below-threshold harmonic generation and is relatively insensitive to the choice of initial conditions. We also find that the short trajectory can only lead to low-energy harmonics for electrons that have been released close to the ion core in a process that is closer to multiphoton than to tunnel ionization.
- OSTI ID:
- 21448518
- Journal Information:
- Physical Review. A, Vol. 82, Issue 2; Other Information: DOI: 10.1103/PhysRevA.82.023401; (c) 2010 The American Physical Society; ISSN 1050-2947
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ATOMS
DIPOLES
ELECTRONS
HARMONIC GENERATION
HARMONICS
IONIZATION
IONS
LASER RADIATION
MULTI-PHOTON PROCESSES
POTENTIALS
QUANTUM MECHANICS
SEMICLASSICAL APPROXIMATION
TRAJECTORIES
TUNNEL EFFECT
APPROXIMATIONS
CALCULATION METHODS
CHARGED PARTICLES
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FERMIONS
FREQUENCY MIXING
LEPTONS
MECHANICS
MULTIPOLES
OSCILLATIONS
RADIATIONS