Analytical study of birefringent cavities for axion-like dark matter search

TL;DR

This paper develops a comprehensive framework to quantify mirror birefringence effects in optical cavities, revealing their impact on axion-like particle dark matter searches and proposing mitigation strategies for sensitivity loss.

Contribution

A nonperturbative analytical framework is introduced to accurately assess birefringence effects, enhancing the understanding of their influence on ALP detection sensitivity.

Findings

Birefringence and misalignment degrade sensitivity in low-mass ALP searches.

Selecting a postselection angle larger than misalignment mitigates sensitivity loss.

Birefringence creates an additional high-mass resonance peak unaffected by misalignment.

Abstract

Light polarization plays a crucial role in optical-cavity experiments; however, mirror birefringence presents a significant challenge that must be addressed carefully. In this study, a rigorous, nonperturbative framework is developed to quantify birefringence effects by incorporating variations in reflectance and polarization misalignment. We analyze the impact of this framework on the sensitivity of axion-like particle (ALP) dark-matter searches. The results show that both birefringence and misalignment contribute to sensitivity degradation in the low-mass regime; however, the adverse effects of misalignment can be mitigated by selecting a postselection angle greater than the misalignment angle. Furthermore, birefringence produces an additional resonance peak in the high-mass region, which remains largely unaffected by misalignment and postselection variations. This rigorous framework underscores the importance of considering birefringence in high-precision optical-cavity experiments for ALP detection.