Abstract: A polarizing cube beamsplitter, which is designed for infrared applications, comprises two 45.degree. prisms made of ZnSe. A first anti-reflection layer, which is a Herpin equivalent layer consisting of the triad of sublayers ZnS-ZnSe-Zns, is deposited onto the hypotenuse of a first one of the prisms. Then, a polarizing stack consisting of a plurality of pairs of thin-film layers of alternating high and low refractive indices is formed on the first anti-reflection layer. One layer in each pair of thin-film layers in the polarizing stack is a Herpin equivalent layer consisting of the triad of sub-layers Te-ZnSe-Te, and the other layer in each pair is a thin film of ZnSe. A layer of prism material ZnSe, which is thick enough to be optically polished, is then formed on the second anti-reflection layer. The hypotenuse of the second prism is likewise optically polished, and is pressed onto the optically polished layer of prism material to form a bond. The resulting beamsplitter is of cubic configuration.