Proposed Active Optical Frequency Standards based on Magneto-optical Trap Trapped Atoms

A new conception of optical frequency standards, active optical frequency standards (AOFS) is under developing. In this report, we propose a novel scheme for active optical frequency standards based on magneto-optical trap (MOT) trapped atoms. With the advantages of 4-level atomic system proposed here, this scheme overcomes the main limitations on the accuracy of active optical clock based on atomic beam due to Doppler effect.