Optical wire-grid polarizers at oblique angles of incidence

Nanotechnology enables the fabrication of wire-grid polarizers (WGP) in the visible optical region. At oblique angles of incidence, WGP can be used as polarizing beam splitters (PBS). As such, they have the advantages of large numerical aperture and high-extinction ratios in both transmission and reflection. Because of these properties, WGP is being explored as PBS replacement in projectors. In this article, we present a complete theoretical investigation of the WGP. Rigorous diffraction theory, exact lowest-order eigenmode effective-media theory, and form birefringence theory are discussed. These theories are compared with experimental measurement of $\mathrm{T(\theta )}$ and $\mathrm{R(\theta )}$ as a function of the polarization state of the input light and as a function of the incident angle θ. It is shown that only the rigorous diffraction theory can fit the data for all incident angles. Using diffraction theory we provide a calculation relating the optical properties of the WGP to the physical dimensions of the wire grids. Thus, a framework for optimizing the optical properties of the WGP for various applications and requirements is provided.