Simultaneous long-time frequency stabilization of two dye lasers for a two-step atomic excitation

Abstract

The authors describe a straightforward and accurate method for the frequency stabilization of two dye lasers on frequencies nu 01 and nu 02, fitting two atomic transitions from the ground state to the first electronically excited state and from there to a higher lying state. They make use of the Doppler shift by monitoring atomic fluorescence when the laser beams are crossed with an atomic beam under angles 90 degrees - Delta alpha and 90 degrees + Delta alpha , respectively. The laser frequency can be stabilized to better than +or-1 MHz for the first and +or-2 MHz for the second transition for periods of hours. The authors apply this stabilization method to collision experiments between two excited Na(nl) atoms.