The width of a wire grid polarizer must be less than the wavelength of the light to effectively minimize light scattering. This design allows the polarizer to behave as a homogeneous object rather than a collection of discrete scatterers. When the wire spacing exceeds the wavelength, the polarizer can disrupt the light's polarization by introducing unwanted scattering effects. The goal is to ensure that the electromagnetic field interacts with the average properties of the device rather than its individual components. This principle is similar to how traditional polarizers utilize long-chain molecules to create an anisotropic medium.
