Bandwidth broadening induced by ionic interactions in polymer stabilized cholesteric liquid crystals

Cholesteric liquid crystals (CLCs) are selectively reflective materials that can exhibit a number of dynamic optical responses. We recently reported on electrically-induced, seven-fold increase in bandwidth in polymer stabilized CLCs (PSCLCs) subjected to DC electric fields. Here, the underlying mechanism of the electrically-controllable bandwidth broadening in PSCLCs is isolated by employing a variety of electro-optic experiments. We conclude that the mechanism is ionic charge trapping by the polymer network which subjects the material system to pitch expansion near the positive electrode and pitch compression near the negative electrode resulting in approximately linear pitch variation throughout the cell thickness. (C) 2014 Optical Society of America