Lightweight stable near-concentric cavity design

In order to engineer and achieve coherent interaction between atoms and photons, optical resonators are fundamental candidates. Governed by cavity quantum electrodynamics, cavity systems require to contain photons in a small mode volume to perform strong atom-light interaction. Conventionally, this small mode volume is achieved through the use of small high-finesse optical resonators. However, a different cavity configuration can also implement small mode volumes, namely large optical resonators operated in the near-concentric regime. Due to their configuration, near-concentric cavities provide a large optical access between the mirrors and only require low-finesse to operate. Nevertheless, a stable cavity length is necessary to perform interaction with a single atom.

We present a lightweight near-concentric cavity design to address the cavity length stability required for single atom interaction. In our new structure, we make use of the equivalence of the transverse and rotational displacements in the near-concentric regime to manage the cavity alignment. We then compare the two movement configurations and demonstrate the superiority of a tip-tilt cavity structure in terms of cavity length stability for the near-concentric regime.