Interference suppression of light backscattering through oblique deposition of high-reflectivity multilayers: a...

We demonstrate a theoretical approach whereby light backscattering toward the incident beam can be suppressed entirely for a high-reflectivity, rough-surfaced multilayer mirror fabricated using oblique deposition, such that the interface relief is replicated at a certain angle β to the sample normal. The mirror comprises two parts: a main (lower) multilayer consisting of N identical bi-layers growing at the angle β_ML to the mirror normal, and an additional bi- or tri-layer forming the topmost section of the mirror, which grows at another angle β_BL. We show that choosing appropriate growth angles β_ML and β_BL results in a disappearance of backscattering toward the incident beam due to the destructive interference of waves scattered from the main multilayer and uppermost bi- or tri-layer. The conditions for the scattering suppression are formulated, and the suitability of different mirror materials is discussed.