Study of Several Error Sources in a Laser Raman Clock

Abstract

We are investigating the development of a cesium clock using a laser excited resonance Raman interaction in place of direct microwave excitation. Such a scheme, employing only semiconductor laser excitation and exploiting fiber optic and integrated optic technology together with a simple atomic beam design, may lead to the development of smaller, lighter and perhaps cheaper atomic clocks. So far, we have been studying a sodium Raman clock which consists of a sodium atomic beam, a dye laser, and an acousto-optic frequency shifter, used for the generation of the second laser frequency. Recent performance showed a stability of 1 x 10-l for a 5000 second averaging time. This compares favorably with commercial cesium clocks, when difference in atom transit time and transition frequency are taken into consideration. In this paper, we describe the results of a study of long term error sources unique to the Raman clock, which include: laser beam misalignment effects, errors caused by the laser frequency being slightly off-resonance with the intermediate state, laser intensity effects, and so on.