Recoil-induced resonances in nonlinear, ground-state, pump-probe spectroscopy - art. no. 063411

A theory of pump-probe spectroscopy is developed in which optical fields dr ive two-photon Raman transitions between ground states of an ensemble of th ree-level atoms. Effects related to the recoil the atoms undergo as a resul t of their interactions with the fields are fully accounted for in this the ory. The linear absorption coefficient of a weak probe field in the presenc e of two pump fields of arbitrary strength is calculated. For subrecoil coo led atoms, the spectrum consists of eight absorption lines and eight emissi on lines. In the limit that chi (1) much less than chi (2) where chi (1) an d chi (2) are the Rabi frequencies of the two pump fields, one recovers the absorption spectrum for a probe field interacting with an effective two-le vel atom in the presence of a single pump field. However. when chi (1) grea ter than or equal to chi (2), new interference effects arise that allow one to selectively turn on and off some of these recoil-induced resonances.