Reducing light scattering in high-reflection coatings through destructive interference at fully correlated interfaces.

Light scattering in quarter-wave high-reflection (QWHR) coatings with fully correlated interfaces was reduced by adding Fabry-Perot (FP) cavity structures on top of the multilayer. The properly designed FP cavity can induce destructive interference for fully correlated interfaces and reduce the scattering loss. Compared to QWHR coatings, adding one FP cavity could decrease the scattering at the near specular angles, and two FP cavities have the potential to reduce light scattering in a broad angular range. A low-scattering HR (LSHR) coating using two FP cavities has been realized to suppress light scattering. The numerical scattering calculation illustrated that the total scattering loss of the LSHR was about 30% less than that of the QWHR coatings. The measured angle-resolved scattering of the LSHR coating showed a good correspondence to the numerical calculation, although a small deviation exists in a limited angular range.