Light frequency shift in small optically pumped cesium beam frequency standards

Optically pumped cesium beam frequency standards (OPCBFS) have better frequency accuracy and stability than the traditional magnetic state selecting cesium beam frequency standards. However, the light frequency shift is a new factor affecting the frequency accuracy and frequency stability in a OPCBFS. In an OPCBFS, to make state selection, the atomic beam from the oven are pimped by a pumping laser light frequency tuned to a D2 transition line of cesium atom. The excited cesium atoms then decay to ground states and emit corresponding photons. The light frequency shifts for different probing schemes were calculated as a function of the oven, temperature, microwave power and laser light intensity.EI