Intensity correlation in frequency upconversion via four-wave mixing in rubidium vapor

We report a study on the transfer of intensity correlation properties in frequency upconversion via four-wave mixing (FWM) in rubidium (Rb) vapor. The 5S(1/2) - 5P(3/2) - 5D(5/2) two-photon transition in 85Rb leads to collimated blue light (CBL) generation at 420 nm by absorbing two input photons of wavelengths 780 nm and 776 nm. The g((2))(tau) intensity correlation measurement of the CBL field reveals that the intensity correlations of the input fields are transferred to the CBL field due to strong atomic coherence in the FWM loop. We also demonstrate that the measured values of g((2))(tau) of the CBL field are reduced by the effect of Doppler broadening of Rb vapor. (C) 2017 Optical Society of America