Precise measurement of the Stark shift of the cesium D1 line

The dc Stark shift of the cesium D1 line has been observed using two 894 nm cavity-stabilized diode lasers locked to resonance signals from an atomic beam and a saturated absorption cell. The heterodyne signal obtained from the two lasers and optical measurement of the electrode spacing allow well calibrated high precision measurements to be made. The observed scalar shift is found to be 115.219 (15) kHz (kV/cm) ^-2. We believe this result to be the most precise Stark shift measurement ever reported.