Electromagnetically induced transparency in an open multilevel system

Electromagnetically induced transparency in a multilevel system is investigated in Yb-173. The level structure investigated is "open" in that the light that gives rise to the transparency also resonantly couples the atoms to excited states which do not exhibit electromagnetically induced transparency. The resulting reduction of transparency is investigated experimentally and theoretically. It is found that, while the transparency is poor in certain regimes, it can be made to perform arbitrarily well in the limit of a large intensity imbalance between the optical fields.