Abstract
In this article, we reveal a theoretical and experimental illustration of the Ferroelectric liquid crystal (FLC) grating fabricated by mean of patterned alignment based on photo-alignment. The complexity related to the mismatching of the predefined alignment domains on the top and bottom substrate has been avoided by incorporating only one side photo aligned substrate while the other substrate does not have any alignment layer. Depending on the easy axis in the said alignment domains and the azimuth plane of the impinging polarized light, the diffracting element can be tuned in two modes i.e. DIFF/OFF switchable and DIFF/TRANS switchable modes, which can be applied to different applications. The diffraction profile has been illustrated theoretically that fits well with the experimental finding and thus the proposed diffraction elements with fast response time and high diffraction efficiency could find application in many modern devices.
Highlights
Liquid crystal (LC) gratings have been used widely for flat-panel display, projection displays and backlight for displays
We reveal a theoretical and experimental illustration of the Ferroelectric liquid crystal (FLC) grating fabricated by mean of patterned alignment based on photo-alignment
In experiments to modulate the diffraction profile, a square wave electric field has been applied to the FLC grating cell, which was placed between the cross polarizers
Summary
Liquid crystal (LC) gratings have been used widely for flat-panel display, projection displays and backlight for displays. The diffraction gratings are formed by non-uniform electrical field and could be further tuned by the biasing voltages.[8] Another approach is to create periodic structure by means of defining initial LC director in two or more distinct alignment domains and afterward, the diffraction profile can be controlled by the electric field.[9,10] Another alternative includes the intrinsic diffraction properties of LCs due to the periodic structure of cholesteric and Ferroelectric liquid crystal (FLC) that have been utilized for various applications.[11] The switchable diffraction gratings with periodic refractive-index modulation arising from layer undulations in cholesteric liquid crystals. The response times for such LC devices are limited to ∼1 ms
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