Applying Tamm plasmon polaritons for determining the birefringence of a thin film.

The anisotropy of a thin film can be created by a wide variety of methods and it has found many applications. Liquid crystal (LC) molecules are aligned in a specific orientation on a rubbed polyimide film for conventional LC displays (LCDs). The rubbing process on the polyimide film controls the azimuthal and polar angles of the LCs, and it can cause physicochemical anisotropy on the polyimide film and produce the birefringence in the azimuthal direction. Knowing the rubbing-induced optical axis of polyimide films is crucial for achieving optimum electro-optical properties of LCDs. The rubbing-induced and the resolution less than 2 deg for determining the optical axis of the rubbed polyimide are obtained by applying Tamm plasmon polaritons in this Letter.