Dispersion Examples: Group Velocity with Anomalous Dispersion

In this example,
the high-frequency wave has a higher
phase
velocity than the low-frequency wave. This is called
anomalous
dispersion. As a result,
the group velocity is much greater than the
phase
velocity of the individual waves; that is, the packets move a
lot faster than the single-frequency waves.

In some cases, the group velocity of light wave packets can be faster than
the speed of light. This is often mistaken for faster-than-light
travel in
news reports. Click the Restart button to see why this
cannot be used for faster-than-light communication; the
signal
velocity is not faster than the speed of light.

Next: Zero Group Velocity
Previous: Group Velocity
Index