Metal–dielectric broad-angle non-polarizing beam splitters with ultrathin copper layer

Abstract

A novel metal–dielectric three-layer cube broad-angle non-polarizing beam splitter (nPBS) with an ultrathin copper layer was designed, prepared and characterized. Our nPBS structure (270 nm thick) is optimized around the wavelength of 1064 nm (reflectance in between 25 and 35% and transmittance in between 55 and 65% for the incidence angle range of 35–55°). For comparison, a 24-layer design for 45° incidence angle solution (6193 nm thick) using dielectric–dielectric nPBS was shown. For manufacturing point of view, reducing the layer number in the coating let eliminate undesirable mistakes during preparation of every layer thickness and decrease the time of whole structure fabrication. During or after multilayer deposition it is necessary to minimize the possibility of metal oxidation by choosing material with low affinity to oxygen. Additionally, it is important to reduce the product price by avoiding more expensive metals like gold and silver. Our nPBS structure was prepared in a single process by using of magnetron sputtering. The measured transmittance and reflectance values are in agreement with the design and the target values. Every single layer thickness error analysis was done.