Even when the phase velocity is faster than light, the group velocity should be slower.
These numbers indicate a group velocity for these structures of approximately 1% of the speed of light in free space.
The group velocity dispersion induced by optical elements in the fluorescence path was measured using white light generated by 800-nm pulses in the same flow cell tilled with water.
Essentially, the group velocity of the wave must fall to zero at that location, dropping in such a way that there is sufficient time for the damping to dissipate all of the wave's energy before it gets to that point.
He counters that when a beam passes between positive- and negative-index media the group velocity is negatively refracted.
Definition of group velocity in US English:
group velocity
noun
Physics
The speed at which the energy of a wave travels.
〔物理〕群速
Example sentencesExamples
Essentially, the group velocity of the wave must fall to zero at that location, dropping in such a way that there is sufficient time for the damping to dissipate all of the wave's energy before it gets to that point.
The group velocity dispersion induced by optical elements in the fluorescence path was measured using white light generated by 800-nm pulses in the same flow cell tilled with water.
These numbers indicate a group velocity for these structures of approximately 1% of the speed of light in free space.
He counters that when a beam passes between positive- and negative-index media the group velocity is negatively refracted.
Even when the phase velocity is faster than light, the group velocity should be slower.