Group velocity, energy velocity, and superluminal propagation in finite photonic band-gap structures
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Date
2001-02-23
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Citation of Original Publication
G. D’Aguanno et al., Group velocity, energy velocity, and superluminal propagation in finite photonic band-gap structures, Phys. Rev. E, Vol. 63, Iss. 3 (2001), https://doi.org/10.1103/PhysRevE.63.036610
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0
This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
We have analyzed the notions of group velocity Vg and energy velocity VE for light pulses propagating inside one-dimensional photonic band gap structures of finite length. We find that the two velocities are related through the transmission coefficient t as VE = |t|²Vg. It follows that VE = Vg only when the transmittance is unity (|t|² = 1) . This is due to the effective dispersive properties of finite layered structures, and it allows us to better understand a wide range of phenomena, such as superluminal pulse propagation. In fact, placing the requirement that the energy velocity should remain subluminal leads directly to the condition Vg <~ c/ |t|² . This condition places a large upper limit on the allowed group velocity of the tunneling pulse at frequencies of vanishingly small transmission.