Bistable Switching of Diffractive Smectic‑A Liquid Crystal Device between Haze-Free Transparent and High-Haze Translucent States

Bistable operation of a phase grating device using smectic-A liquid crystals (SmA-LCs) is presented. The SmA-LC cell can be operated with very low power because it consumes power only while the state is being switched. This device uses the simple dielectric switching mechanism, and it is free from degradation by the impurity ions. For the switching of an SmA-LC cell, we formed interdigitated electrodes on both the top and bottom electrodes to apply the in-plane and vertical electric fields. We can control the diffracted light intensity easily by the change in the magnitude or duration of the applied voltage wave. We have shown that 98.1% of the incident light can be transferred from the zeroth to higher orders. Owing to the high diffraction efficiency, this device can provide an excellent translucent state. Moreover, it can provide the haze-free transparent state because an SmA-LC cell does not contain a polymer structure or impurity ions. We have shown that the device can provide outstanding performance, such as low power consumption, strong diffraction, high transmittance, high-haze translucent state, and high reliability for over 2 weeks. We expect that the device can be applied to switchable windows and window displays.