Dynamic control of EIT by changing optical phase

We have studied phase dynamics in EIT in a dense rubidium vapor. We have observed a very fast growth of the absorption when the phase of the optical field was abruptly changed, followed by a slow return to the steady state absorption. Then the transmission was slowly restored to stationary magnitude. The recovery time is on the order of the transit time of the atom flying through the laser beam and decreases with increasing optical power. The fast variation of the transparency is proportional to the phase deviation. The obtained result can be used for the fast control of EIT, for example, in an optical switch.