Constructive interference atomic clock scheme based on coherent population trapping and an extended optical cavity

We studied experimentally a left-right circularly polarized light feedback scheme. A vertical-cavity surface-emitting laser (VCSEL) and partial retroreflector formed an extended cavity, allowing similar to 4% of the laser to enter the VCSEL. Such design helped to improve the microwave modulation efficiency. Comparing to the conventional circularly polarized light scheme, the resonance amplitude of this method was doubled while the noise was reduced five times because of the usage of the left-right circularly polarized light, which continuously interacted with atoms. The short-term instability was improved by one order of magnitude. This scheme can be applied to small or chip-scale atomic clocks. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement