High-resolution coherence spectroscopy using pulse trains

Abstract

An infinite train of short light pulses is used for periodic creation of a coherent superposition of atomic substates. The coherence is sensitively detected by an optical probe beam using a polarization-selective technique. Narrow resonances are observed whenever the pulse repetition rate or its multiples coincide with an atomic Bohr frequency. Half-widths (full width at half maximum) of 20 kHz have been obtained for the Zeeman splitting of the sodium ground state.