Beyond one-second laser coherence via active optical atomic clock

In this report we present the possibility to realize laser coherence time beyond one second via the principle of active optical atomic clock, which is a laser with cavity mode linewidth is much wider than the linewidth of medium gain profile. By optimizing the parameters of active optical atomic clock based on laser cooled atomic beam, the calculation shows one can reach ten-second coherence time of laser light. More longer coherence time is still possible along this new way.