Research of Light Shift in Pulse Light Detected Compact Cesium Beam Clock

Compact cesium beam clocks play significant roles in navigation, time-keeping and precision measurements. In comparison to the traditional detection method using inhomogeneous magnetic fields, ionizers and electron multipliers, the optical detection method avoids complicated structures. In consequence of introducing laser to the system, the light shift influences the clock’s long-term stability. We present a new method to suppress the light shift by using pulsed light instead of continuous light. The method only detects part of the atoms which do not interact with light and microwave simultaneously therefore reduces the light shift. We demonstrate the validity and the results correspond to our expectation in different pulse duty cycles and pulse frequencies. We test this method on a clock which adopts the optically detected magnetic-state-selection scheme. Under optimum value conditions light shift coefficient is reduced from (1.63 ± 0.04)E–12/mW to (1.15 ± 0.03)E–13/mW. The method can be used to optimize the long-term frequency stability of cesium beam clocks.