National Sun Yat-sen University of Kaohsiung

Yu-Chieh Li

Chun-Ta Wang

Tsung-Hsien Lin

Cheng-Chang Li

Li-Min Chang

Kuan-Wu Lin

Duan-Yi Guo

Yi-Te Chuang

Cheng-Kuan Wu

A cholesteric liquid crystal polarizing grating includes two substrates, two alignment layers, and a liquid crystal layer. An interlayer space is formed between the two substrates. The two alignment layers are respectively located on inner surfaces of the two substrates facing the interlayer space. Alignment directions of the alignment layers are periodically arranged. An alignment plane of each alignment layer is divided into a plurality of rows. The alignment directions in a same row are the same, and the alignment directions in adjacent rows rotate relative to each other. The plurality of rows with the alignment directions rotated by 180 degrees defines a grating period. The liquid crystal layer is located in the interlayer space. Liquid crystal molecules adjacent to the two alignment layers are arranged following the alignment direction of each alignment layer to form a polarizing grating with the grating period.

Cholesteric liquid crystal polarizing grating

A switching method for a liquid crystal polarizing grating is provided to solve the problems of low diffraction efficiency and incapability in switching between reflection and transmission modes of a conventional polarizing grating. The switching method includes five steps. In an initial step, no voltage is applied, and liquid crystal molecules of cholesteric liquid crystal layer of the liquid crystal polarizing grating are arranged in a planar structure. In a first step, a first alternating current voltage with a first frequency is applied. In a second step, a second alternating current voltage with a second frequency is applied. In a third step, a third alternating current voltage with a third frequency is applied. In a fourth step, a fourth alternating current voltage with a fourth frequency is applied, and the liquid crystal molecules are arranged in a uniform lying helix structure.

Switching method for switching a liquid crystal polarizing grating between trnsmission difraction and reflection difraction

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Kaohsiung, Taiwan

Yu-Chieh Li