We report a facile method to prepare an array of liquid-crystal polarization converters (LCPCA) based on hydrophobic microcavity arrays. The reactive ion etching (RIE) technique was chosen to treat the homeotropic polyimide (PI(sic) ) layers through a metal mask with a through-hole array. Under the selective RIE treatment, a hydrophobic-hydrophilic pattern is obtained due to the increase in surface energy in the etched area from similar to 34.6 to similar to 73.2 mN/m. The etched area forms a microcavity with a diameter of 520 mu m, depth of similar to 23 nm, and center distance of 690 mu m, which is consistent with the dimensions of the metal mask. Since the walls of the microcavity retain hydrophobicity, the liquid-crystal (LC) molecules show a radial arrangement in the microcavity. Combining a substrate covered by a parallel rubbed homogeneous polyimide (PI(()sic)) layer with the substrate covered by a microcavity-patterned PI layer can form a "sandwich " structure. The LC molecules in the microcavities are arranged in a twisted-radial texture, which can convert linearly polarized light to radially or azimuthally polarized light depending on the polarization direction of the incident light. The proposed method has the merits of simple steps, controllable size, and easy to fabricate large-area arrays. Our LCPCA has potential applications in tight focus, material processing, biological tissue analysis, particle capture, and optical data storage.
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