Proposed near-future upgrades of the current advanced interferometric gravitational wave detectors include the usage of frequency dependent squeezed light to reduce the current sensitivity-limiting quantum noise. We quantify and describe the degradation effects that spatial mode-mismatches between optical resonators have on the squeezed field. These mode-mismatches can to first order be described by scattering of light into second-order Gaussian modes. As a demonstration of principle, we also show that squeezing the second-order Hermite-Gaussian modes HG02 and HG20, in addition to the fundamental mode, has the potential to increase the robustness to spatial mode-mismatches. This scheme, however, requires independently optimized squeeze angles for each squeezed spatial mode, which would be challenging to realise in practise.
@article{arxiv.1704.08237,
title = {Multi-spatial-mode effects in squeezed-light-enhanced interferometric gravitational wave detectors},
author = {Daniel Töyrä and Daniel D. Brown and McKenna Davis and Shicong Song and Alex Wormald and Jan Harms and Haixing Miao and Andreas Freise},
journal= {arXiv preprint arXiv:1704.08237},
year = {2017}
}