Anisotropic antireflection coatings: use as a laser intracavity polarization-direction selector

A double-layer anisotropic antireflection coating is designed and fabricated using the technique of serial bideposition. Both layers in the coating are biaxial with nanostructural columns directed normal to the substrate. Incident light with the p polarization encounters a pair of quarter-wave layers with refractive indices that satisfy the standard relationship for zero reflectance at the design wavelength. Light with the s polarization meets non-quarterwave layers and different indices and hence is partially reflected. As an example to illustrate potential applications of the coating, we have used a thin glass plate with anisotropic antireflection coatings on both sides as an intracavity element to select the direction of polarization of an open-cavity HeNe laser.