Electromagnetically Induced Transparency in the Far-off Resonance Trap of Cs Atoms

In this experiment, electromagnetically induced transparency\,(EIT) in the far-off-resonance optical trap of Cs atoms is investigated. The optical trap is generated by an Nd:YAG laser\,(1064\,nm) of laser power 3.4 W, and beam waist 150 \,$\mu$m with the trap depth about 70\,$\mu$K and is trapped about $2.6\times10^5$ atoms. The cascade EIT is operated with two counter-propagating beams, probe and coupling, which are superimposed on the optical trap with the size of coupling beam slightly larger than the probe beam. The probe laser is at transition from $|6S_{1/2},\,F=4\rangle$ to $|6P_{3/2},\,F=5\rangle$ and the coupling laser is from $|6P_{3/2},\,F=5\rangle$ to $|8S_{1/2},\,F=4\rangle$. The frequency of probe laser is stabilized and fixed while frequency of the coupling laser is scanned through the resonance of $6P_{3/2}$ to $8S_{1/2}$. A numerical simulation by solving the steady state density matrix fits well with the experimental profile.