Polarization induced instabilities in external four-mirror Fabry-Perot cavities

TL;DR

This paper investigates polarization-induced instabilities in four-mirror Fabry-Perot cavities, highlighting how mirror misalignments affect polarization and stability, and proposing a tetrahedral configuration to significantly reduce these instabilities.

Contribution

It provides a comparative analysis of mechanical stability and polarization effects in four-mirror cavities, introducing a tetrahedral configuration to mitigate instabilities caused by mirror motions.

Findings

Mirror misalignments induce polarization and stacking power instabilities.

Instabilities increase with the finesse of the cavity.

Tetrahedral configuration reduces instability parameter by over two orders of magnitude.

Abstract

Various four-mirror optical resonators are studied in the perspective of realizing passive stacking cavities. A comparative study of the mechanical stability is provided. The polarization properties of the cavity eigenmodes are described and it is shown that the effect of mirror misalignments (or motions) induces polarization and stacking power instabilities. These instabilities increase with the finesse of the Fabry-Perot cavity. A tetrahedral configuration of the four mirrors is found to minimize the consequences of the mirrors's motion and misalignment by reducing the instability parameter by at least two orders of magnitude