abstract:In experimental atomic physics, saturated absorption spectroscopy or Doppler-free spectroscopy is a set-up that enables the precise determination of the transition frequency of an atom between its ground state and an optically excited state. The accuracy to which these frequencies can be determined is, ideally, limited only by the width of the excited state, which is the inverse of the lifetime of this state.
The high resolutionspectrumcan be obtained through manymethods, such assaturatedabsorptionspectroscopy, Doppler free methodsoftwo-photonspectroscopy, and etc.