Electrically controlled birefringence colours in deformed helix ferroelectric liquid crystals

A short helix pitch (p 0 = 0.45 µm) ferroelectric liquid crystal (FLC) mixture was found to provide four electrically switched birefringence colours: blue, green, yellow and red. The contrast ratios of the birefringence colours were measured as functions of both driving voltage amplitude and frequency. The FLC mixture, which had a relatively high birefringence, Δn⩾0.2, was controlled by a voltage less than 5 V. A simple model is proposed, which was confirmed by experiments. A possible application is discussed in field‐sequential colour displays, where fast switching times are required.