Open Access Paper
30 September 2011 Tunneling of ultrashort EM wave pulses in gradient metamaterials: paradoxes and perspectives
A. B. Shvartsburg
Author Affiliations +
Abstract
Amplitude - phase spectra of IR waves tunneling through a gradient dielectric nanophotonic barrier, found in the framework of an exactly solvable model of this medium, are used for optimization of superluminal reshaping of tunneling pulses. This barrier, characterized by a cut-off frequency Ω, determined by the shape of distribution of refractive index across the barrier, provides a tunneling regime for waves whose frequencies are less than Ω. In a spectral range located nearby this cut-off frequency Ω, an almost reflectionless tunneling of these waves occurs, accompanied by large strongly dispersive phase shifts. These shifts outstrip in some spectral range the phase shifts accumulated by the same harmonics along the same way in free space. Depending on the detuning between the pulse carrier frequency ω0 and Ω the interplay between superluminal (tunneling) and subluminal (transparent) harmonics results in an ultrafast reshaping of the transmitted waveform, yielding a pulse spatial broadening, formation of superluminal precursors at the front edge of transmitted pulse and the splitting of pulse's maximum, while the displacement of the centre of gravity of reshaped pulse as well as the velocity of energy transfer stay subluminal.
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A. B. Shvartsburg "Tunneling of ultrashort EM wave pulses in gradient metamaterials: paradoxes and perspectives", Proc. SPIE 8172, Optical Complex Systems: OCS11, 81720F (30 September 2011); https://doi.org/10.1117/12.902818
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KEYWORDS
Phase shifts

Dielectrics

Wave propagation

Refractive index

Femtosecond phenomena

Free space

Metamaterials

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