Wavelength tuning the photonic band gap in chiral nematic liquid crystals using electrically commanded surfaces

In this letter, the authors demonstrate photonic band gap (PBG) tuning in chiral nematic liquid crystals using electrically commanded surfaces consisting of a ferroelectric liquid crystal. The electrically commanded surfaces generate a contraction of the pitch of the chiral nematic which is manifested as a blueshift of the PBG. Results are presented which demonstrate that tuning can be achieved by either varying the frequency or the amplitude of the electric field. The maximum shift observed for the long-wavelength band edge was 23 nm for an electric field strength of 20 V μ m − 1 and a frequency of 800 Hz to 1 kHz .