Abstract

Bistable electrical switching of high-efficiency grating diffractions is realized by adding a front $\pi$-bistable twisted nematic ($\pi$-BTN) cell to a passive liquid crystal polarization grating (LCPG). The $\pi$-BTN cell can be switched between stable non- and 180°-twisted states, acting as a polarization converter that switches the polarization of a laser beam and thus changes the diffraction behavior of the LCPG. Both states of the $\pi$-BTN cell are stable and can be reversibly switched to each other by applying a voltage pulse of different frequencies. We experimentally demonstrate two bistable-switching operations: (i) the BTN–LCPG can either split or deflect the laser beam; and (ii) the BTN–LCPG can selectively diffract the laser beam to the $+1$st and $-1$st orders, while maintaining a high diffraction efficiency of $\sim 90\%$. With electrical switchability, a simple optical design, and low power consumption, the proposed BTN–LCPG concept is favorable in various applications.

© 2019 Optical Society of America

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