Suppression of forward-propagating stimulated hyper-Raman emission in cesium vapor due to four-wave-mixing interference

The suppression of forward-propagating stimulated hyper-Raman (SHR) emission is well studied in sodium vapor. Theory predicts that SHR emission to a state linked to the gound state by a one-photon transition is suppressed by an interference with a four-wave-mixing (FWM) emission that links that state to the ground state. Since FWM emission only propagates in the forward direction due to phase-matching considerations, only the forward SHR emission is suppressed. This has been previously demonstrated in sodium. An obvious corollary to this theory is that no suppression occurs if the state is not linked to the ground state by a one-photon transition. A serendipitous arrangement of energy levels in cesium allowed this corollary to be tested and confirmed here.