Electromagnetically induced two-photon absorption reduction in sodium vapor

Summary form only given. It is well known that two-photon absorption can be greatly enhanced whenever a single photon energy approaches an allowed atomic transition. If more than one intermediate state exists, the two-photon absorption can be annihilated depending on the location of the intermediate states. In case there is only one intermediate state, a control laser can be applied to couple the intermediate state with other state to create two dressed states. Then, the medium can be made transparent against two-photon absorption in the presence of multiple pathways. We report the first observation of electromagnetically induced two-photon absorption reduction in sodium vapor.