Electrically switchable and optically rewritable reflective Fresnel zone plate in dye-doped cholesteric liquid crystals

Department of Physics, National Cheng Kung University, 臺南市, Taiwan, Taiwan
Optics Express (Impact Factor: 3.49). 11/2007; 15(21):14078-85. DOI: 10.1364/OE.15.014078
Source: PubMed


This work demonstrates a reflective Fresnel zone plate based on dye-doped cholesteric liquid crystals (DDCLC) using the photo-induced realignment technique. Illumination of a DDCLC film with a laser beam through a Fresnel-zone-plate mask yields a reflective lens with binary-amplitude structures - planar and focal conic textures, which reflect and scatter probed light, respectively. The formed lens persists without any external disturbance, and its focusing efficiency, analyzed using circularly polarized light, is ~ 23.7%, which almost equals the measured diffraction efficiency of the used Fresnel-zone-plate mask (~ 25.6%). The lens is thermally erasable, rewritable and switchable between focusing and defocusing states, upon application of a voltage.

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