Low-reflectivity wire-grid polarizers multilayered by the glancing-angle-deposition technique

Abstract

We have examined antireflection (AR) coatings for high reflectivity metals such as Al on the basis of the admittance diagram. The proposed AR coatings consist of bilayers of absorptive and dielectric materials. A wide variety of materials can be used for AR coatings by tuning the thicknesses of both the absorptive and the dielectric layers. The bilayered AR concept has been applied to reduce the reflectance of wire grid (WG) polarizers made of Al. An absorptive FeSi2 layer has been deposited by the glancing angle deposition technique immedi- ately on the top of Al wires covered with a thin SiO2 layer. For the optimum combination of the thicknesses of FeSi2 and SiO2, the reflectance reduces to lower than a few percent independent of the polarization, whereas the transmission polarization properties remain favorable. We have demonstrated that Ge is also appropriate for the low-reflectivity WG polarizers as an absorptive material. Because low-reflectivity WG polarizers are completely composed of inorganic materi- als, they are useful for applications requiring thermal durability, such as liquid crystal projection displays. C