Spatial separation effects in a guiding procedure in a modified ion-beam-sputtering process

In the present state of the art, ion beam sputtering is used to produce low-loss dielectric optics. During the manufacturing of a dielectric layer stack, the deposition material must be changed, which requires rapid mechanical movement of vacuum components. These mechanical components can be regarded as a risk factor for contamination during the coating process, which limits the quality of high-end laser components. To minimize the particle contamination, we present a novel deposition concept that does not require movable components to change the coating material during the coating process. A magnetic field guiding technique has been developed, which enables the tuning of the refractive index in the layer structure by sputtering mixtures with varying compositions of two materials using a single-ion source. The versatility of this new concept is demonstrated for a high-reflection mirror. A thin-film coating deposition process that uses magnetic control fields offers reduced contamination and improved control. The technique, developed by scientists at Laser Zentrum Hannover in Germany, is based on ion-beam sputtering, a well-established scheme for fabricating optical coatings, whereby a stream of ions are used to eject atoms from a target onto a substrate. The team’s innovation is to introduce magnetic fields that guide the sputtered material to the substrate. The approach removes the need for movable mechanical components in the deposition apparatus, which can act as contamination sources. It also provides fine control over the thickness and refractive index of the layer being deposited. Experiments with a TiO2/Al2O3 sputter target demonstrated that the approach can fabricate highly reflecting coated mirrors for visible light.