Group velocity, energy velocity, and superluminal propagation in finite photonic bandgap structures
Abstract
We have analyzed the notions of group velocity V_{g} and energy velocity V_{E} for light pulses propagating inside onedimensional photonic band gap structures of finite length. We find that the two velocities are related through the transmission coefficient t as V_{E}=\t\^{2}V_{g}. It follows that V_{E}=V_{g} 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 V_{g}<=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.
 Publication:

Physical Review E
 Pub Date:
 March 2001
 DOI:
 10.1103/PhysRevE.63.036610
 Bibcode:
 2001PhRvE..63c6610D
 Keywords:

 42.25.Bs;
 42.70.Qs;
 73.40.Gk;
 Wave propagation transmission and absorption;
 Photonic bandgap materials;
 Tunneling