Reducing light-shift effects in optically-pumped gas-cell atomic frequency standards

We investigate a novel method to suppress the light-shift effect in laser-pumped passive rubidium frequency standards. The reduction of the light-shift due to additional frequency components in the pumping light is studied theoretically and compared to experimental results obtained with a frequency-modulated DBR laser diode as a pumping light source. In this way, a reduction of the light shift by a factor of 55 was successfully demonstrated. Complete cancellation of the light shift can be reached with a suitably adjusted modulation index and frequency.