Internal reflections of the gaussian beams in Faraday isolators

The reflection coefficient of the Faraday isolator-mirror system in the presence of internal reflections of the incident Gaussian beam is theoretically and experimentally explored for three different architectures of a Faraday isolator. In every case, these internal reflections are shown to alter widely the behavior of the system. In particular, we propose and test a design using a quarter-wave plate that can, in some experiments, give better isolation ratios than conventional isolators.