Without the DC
voltage, the LC molecules align parallel to the surface of the
substrates and the helical axis is perpendicular to the substrate.
Increasing the applied voltage, the direction of the helical axes
is disordered and the polarization of the fluorescence is lost.
When the DC voltage is turned off, the polarization of the
fluorescence is recovered. This result indicates that the colour
of the fluorescence can also be tuned between green and yellow
by the application of DC voltage. The response time is in the
order of several hundred ms.