2-PHOTON FOURIER SPECTROSCOPY WITH FEMTOSECOND LIGHT-PULSES

We demonstrate a Fourier spectrometer that uses intense ultrashort las er pulses. By exciting the 6S(1/2)-8S(1/2) two-photon transition in at omic cesium vapor, we are able to measure the small hyperfine splittin g of the 8S(1/2) excited state. This technique, combining a high spect ral resolution with the high peak intensities available to femtosecond laser systems, may offer intriguing opportunities for the study of mu ltiphoton transitions and for spectroscopy in the short-wavelength reg ion. (C) 1997 Optical Society of America.