Diffraction-limited Fabry-Perot Cavity in the Near Concentric Regime

TL;DR

This paper demonstrates a nearly concentric Fabry-Perot cavity with an anaclastic design that achieves diffraction-limited performance and strong coupling in cavity QED applications without requiring high finesse or extremely small cavity volumes.

Contribution

The authors introduce an anaclastic cavity design that simplifies mode matching and maintains diffraction-limited performance in the near concentric regime.

Findings

Achieves diffraction-limited mode in a nearly concentric cavity.

Simplifies mode matching compared to plano-concave cavities.

Enables strong coupling in cavity QED without high finesse.

Abstract

Nearly concentric optical cavities can be used to prepare optical fields with a very small mode volume. We implement an anaclastic design of a such a cavity that significantly simplifies mode matching to the fundamental cavity mode. The cavity is shown to have diffraction-limited performance for a mode volume of $\approx10^4\lambda^3$. This is in sharp contrast with the behavior of cavities with plano-concave mirrors, where aberrations significantly increase the losses in the fundamental mode. We estimate the related cavity QED parameters and show that the proposed cavity design allows for strong coupling without a need for high finesse or small physical cavity volume.