733 research outputs found
Laserâdriven strongâfield Terahertz sources
A review on the recent development of intense laserâdriven terahertz (THz) sources is provided here. The technologies discussed include various types of sources based on optical rectification (OR), spintronic emitters, and laserâfilamentâinduced plasma. The emphasis is on OR using pump pulses with tilted intensity front. Illustrative examples of newly emerging applications are briefly discussed, in particular strongâfield THz control of materials and acceleration and manipulation of charged particles
Linear and nonlinear waves in surface and wedge index potentials
We study optical beams that are supported at the surface of a medium with a linear index potential and by a piecewise linear wedge type potential. In the linear limit the modes are described by Airy functions. In the nonlinear regime we find families of solutions that bifurcate from the linear modes and study their stability for both self-focusing and self-defocusing Kerr nonlinearity. The total power of such nonlinear waves is finite without the need for apodization
Multiple filamentation induced by input-beam ellipticity
The standard explanation for multiple filamentation (MF) of intense laser
beams has been that it is initiated by input beam noise (modulational
instability). In this study we provide the first experimental evidence that MF
can also be induced by input beam ellipticity. Unlike noise-induced beam
breakup, the MF pattern induced by ellipticity is reproducible shot to shot.
Moreover, our experiments show that ellipticity can dominate the effect of
noise, thus providing the first experimental methodology for controlling the MF
pattern of noisy beams. The results are explained using a theoretical model and
simulations
Photoluminescence and Terahertz Emission from Femtosecond Laser-Induced Plasma Channels
Luminescence as a mechanism for terahertz emission from femtosecond
laser-induced plasmas is studied. By using a fully microscopic theory, Coulomb
scattering between electrons and ions is shown to lead to luminescence even for
a spatially homogeneous plasma. The spectral features introduced by the rod
geometry of laser-induced plasma channels in air are discussed on the basis of
a generalized mode-function analysis.Comment: 4 pages with 2 figures
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