Accumulation of dwell times in light diffusion
We discuss various speeds of propagation that are relevant for the dynamics of classical waves in random media: phase velocity, group velocity and transport velocity. The transport velocity can be much smaller than the phase velocity due to the long dwelling of classical waves inside resonant scatterers. We show that the transport velocity of light can be obtained experimentally by studying both transient and steady-state diffusion of light.
Lagendijk, A, & van Tiggelen, B. A. (1993). Accumulation of dwell times in light diffusion. Physica A, 200, 433–442.