The Power and Limitations of Polymers and Liquid Crystals for Polarization Control

Historically, high-quality polarizers like Glan-Thompson types made from calcite have delivered exceptional extinction ratios but come with drawbacks such as small apertures, limited angular fields, and high cost due to the scarcity of optical-grade calcite.

Dichroic sheet polarizers are now more common, offering large apertures and wide viewing angles, ideal for displays. However, they underperform in UV and IR ranges and have lower flux tolerance. Newer innovations like silver nanoparticle polarizers—produced by stretching and thermally treating silver-doped glass—offer visible to IR coverage but often suffer from poor transmitted wavefront quality unless laminated between flat glass layers.

Wiregrid polarizers, driven by LCD projector market needs, have advanced significantly. Using sub-wavelength aluminum wire structures deposited on substrates, they support visible and IR applications with clear apertures up to 18 cm. However, they require thin, flexible wafers, which can impact flatness and reflected wavefront quality. Surface coatings improve durability and add anti-reflection properties.

Combining various types, such as linear and wiregrid polarizers, has enabled the creation of broadband polarizers effective up to 2.7 microns. These compact solutions offer better angular acceptance and aperture sizes than traditional crystal-based versions.

Beam-splitting polarizers like the MacNeille design have been enhanced by embedding wiregrids within prisms, improving angular performance and making polarization direction independent of the incident light angle. Still, challenges like wavefront distortion and absorption persist.

In essence, while traditional and modern polarizer technologies each have distinct advantages and limitations, ongoing innovation—especially in polymer and nanostructure integration—continues to expand their capabilities across wider spectral ranges and application domains.