Fast-switching bistable cholesteric intensity modulator.

A fast-switching bistable optical intensity modulator is demonstrated. Using a dual-frequency cholesteric liquid crystal, the direct switching is achieved from the scattering focal conic state to the transparent long-pitch planar state. In comparison with the bistable cholesteric devices proposed previously, our device, characterized by its capability of direct two-way transitions between the two bistable states, possesses a very short transition time from the focal conic state to the planar state as short as 10 ms. No voltage has to be applied to sustain the optical states, making the device low energy consuming. Potential applications of this device are addressed.