Two photon absorption and coherent control with broadband down-converted light

The two-photon absorption in rubidium was investigated with broadband down-converted light. The pulse-shaping methods were used to control two-photon absorption, which demonstrated that the spectral and temporal resolutions were 3-5 orders of magnitude below the actual bandwidth and temporal duration of the light. The pulse shaper separates the spectral components of the beam and ultilizes a computer controlled spatial light modulator (SLM) to introduce desired spectral phase filter to the light. It was found that the broadband down-converted light induced two-photon absorption with the same sharp temporal behavior as femtosecond pulses.