Characterization of optical systems for the ALPS II experiment

TL;DR

This paper characterizes the optical systems of the ALPS II experiment, focusing on achieving high power build-up in long optical cavities to detect weak signals from hypothetical particles.

Contribution

It provides detailed analysis and results of the optical cavity systems essential for the sensitivity of the ALPS II experiment.

Findings

High power build-up factors achieved in a 20 m cavity

Effective control systems maintain resonance and coupling

Results inform the design of ALPS II optical setup

Abstract

ALPS II is a light shining through a wall style experiment that will use the principle of resonant enhancement to boost the conversion and reconversion probabilities of photons to relativistic WISPs. This will require the use of long baseline low-loss optical cavities. Very high power build up factors in the cavities must be achieved in order to reach the design sensitivity of ALPS II. This necessitates a number of different sophisticated optical and control systems to maintain the resonance and ensure maximal coupling between the laser and the cavity. In this paper we report on the results of the characterization of these optical systems with a 20 m cavity and discuss the results in the context of ALPS II.