Using a front bistable twisted nematic film realize bistable electrical switching of polarization grating diffractions

Te-Wei Chiang^1*, Chun-Ta Wang¹, Alwin Tam², Man-Chun Tseng², Chung-Yung Lee², Tsung-Hsien Lin¹, Hoi-Sing Kwok²

¹Department of Photonics, National Sun Yat-Sen University, Kaohsiung, Taiwan
²State Key Laboratory on Advanced Displays and Optoelectronics Technologies, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong

* Presenter:Te-Wei Chiang, email:attitude9610507@gmail.com

Adding a front π-bistable twisted nematic (π-BTN) cell to the liquid crystal polarization grating (LCPG) realizes bistable electrical switching of high efficiency grating diffractions. The π-BTN cell can be switched between stable non- and 180°-twisted states, which switche the polarization of laser beam and changes the diffraction property of the LCPG. Applying voltage pulse of different frequencies can make reversibe switch between the two stable states. This device can perform two bistable-switching operations: the BTN–LCPG can either split or deflect the light and it can selectively diffract the beam to the 1st and −1st orders, while maintaining a high diffraction efficiency. The BTN–LCPG is favourable in various applications due to electrical switchability, simple optical design, and low power consumption.

Keywords: π-bistable twisted nematic cell, liquid crystal polarization grating diffractions.