TRAVERSAL TIME AS A FUNCTION OF THE SIZE OF THE WAVEPACKET

We calculate numerically the transmission coefficient and the traversa l time for finite Gaussian wavepackets as a function of their widths. We consider electromagnetic waves crossing a slab and a periodic struc ture. We find that the periodic structure can be crossed at superlumin al velocities for wavenumbers in the optical gap and sizes larger than the thickness of the system. The corresponding transmission coefficie nts are very small. The long wavepacket limit of the traversal time co incides with previous analytical results for the real component of the interaction time. The imaginary component of this time only affects t he change in size of the wavepacket.