Fig. 8.

Change in various optical losses plotted vs. linear polarization angle ϕ relative to the [$0\overline{1}\overline{1}$] crystallographic plane. About 8 ppm peak-to-peak variation is measured in total loss (1-R) cavity ring-down (CRD) measurements between orthogonal input polarization states, reproducing the qualitative behavior observed for absorption A via photothermal common-path interferometry (PCI). Direct transmission measurements (DIRT) suggested no polarization dependence in coating transmittance.