  We demonstrate that a Doppler broadened two-level medium can be made
transparent to a laser pulse by an appropriate adiabatic variation of the laser
field amplitude and its nominal detuning. This new technique of adiabatic
self-induced transparency (ASIT) is compared with the well known self-induced
transparency (SIT) phenomenon, showing that the adiabatic method is much more
robust to variations of the system parameters. We also discuss a possible
experimental implementation of ASIT using 87-Rb atoms.
