Department of Nuclear and Atomic Physics Seminars

An energy flow approach to the propagation of electromagnetic pulses through highly dispersive media

by Nanda Lipsa (Dept. of Physics, IIT Kanpur)

Friday, November 27, 2009 from to (Asia/Kolkata)
at Colaba Campus ( AG-80 )
We study the traversal times of electromagnetic pulses across highly dispersive media, including media with negative dielectric permittivity and magnetic permeability parameters, using the time moments of the Poynting vector at a given point. We have investigated the transport of optical pulses in a variety of situations, such as, through electrical plasmas and negative refractive index media (NRM) of infinite and semi-infinite extents where no resonant effects come into play, as well as slabs of dispersive media where coupling to the Fabry-Pérot slab modes and surface plasmon modes can occur. We find evidence for the Hartman effect at small distances of traversal compared to the free space pulse length inside plasmas. We have also studied the effects of large bandwidth as well as large dissipation in smoothening out the sharp features of Fabry-Pérot resonances that appear in slabs of dispersive media. We have analyzed the behaviour of the arrival times and the temporal widths of a pulse in media with finite anomalous bandwidth, where a crossover of superluminal pulse propagation to subluminal propagation occurs with increase in the propagation distance. We explain this transition that is generic to all cases with a finite bandwidth for anomalous dispersion. Studies of pulse traversal times and widths for various kinds of media including media with electromagnetically induced transparency and gain will be presented
Organised by Sushil Mujumdar
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