Linear polarization rotators based on dye-doped liquid crystal cells

Abstract

Linear polarization rotator is fabricated by a single-side homogenously aligned dye-doped liquid crystal cell and linear variable neutral density filter (LVNDF). When a pump beam passing through the transmittance-linear region of LVNDF irradiates on the untreated surface, the surface LC director in the irradiation region is photoaligned into a continuous twist from 0° to 90°. Consequently, the bulk director gradually transits from a homogeneous to twist orientation. This device is capable of rotating the polarization of an input linearly polarized light depending on the beam position, exhibiting a large continuous twist region (5.6 mm) and high contrast ratio (∼1000:1).