Using a single anisotropic thin film as a phase retarder for oblique incident wave

摘要

This work presents a wide angle phase retarder by using a single anisotropic Ta_2O_5 columnar thin film. The single anisotropic Ta_2O_5 columnar thin film can provide phase retardation between two tangential eigenvectors to modulate the polarization state of light reflected from the prism-coupling system (BK7 prism/anisotropic thin film/air), In experiment, glancing angle deposition technique is used to prepare single layer film of Ta_2O_5 tilted nanorod array with thickness 270nm. hi this analysis, we use wave tracing based on the Berreman calculus to calculate the variations of phases of eigen-waves in the anisotropic thin film as the electromagnetic wave is incident to the prism-coupling system. The uniform phase retardation can be observed in a wide angle range. A linearly polarized incident ray can be reflected as a specific elliptical polarized ray uniformly over the range. Similarly, the wide angle and broadband polarization conversion reflectance with high efficiency also exists in the single anisotropic Ta_2O_5 columnar thin film. The single anisotropic Ta_2O_5 columnar thin film can be useful for the further application in optical components design.