High-Resolution Two-Photon Spectroscopy with Picosecond Light Pulses

Abstract

We have demonstrated the feasibility of Doppler-free two-photon spectroscopy with a train of picosecond standing-wave light pulses from a synchronously pumped mode-locked cw dye laser. The actively controlled mode spectrum provides a means for accurate measurements of large frequency intervals. From a multipulse spectrum of the sodium $3s\ensuremath{-}4d$ transition we have determined a new value of the $4d$ fine-structure splitting, 1028\ifmmode\pm\else\textpm\fi{}0.4 MHz.