The present invention provides a polarization independent phase modulator for light comprising a layer of chiral liquid crystal mixture that has a low enough pitch to provide polarization independence of the effective refractive index for visible light. The liquid crystal mixture is controllable between a helix oriented ground state and a tilted state induced by the application of an electric field across the liquid crystal mixture layer. The liquid crystal mixture is preferably dispersed in a network material which ensures that the helix-oriented ground state is resumed when removing the electric field.