The quadratic electro-optical effect in ferroelectric liquid crystal helical nanostructures: role of the driving voltage shape

Recently it was shown that in deformed helix ferroelectric (DHF) structure, the electrically controlled birefringence of chiral smectic C* phase with subwavelength helix pitch ( is known to be proportional to the square of the electric field E) depends on the cell thickness and on the frequency of applied voltage, given as a Step function of the time. The purpose of the present work is to investigate whether this quadratic effect depends also on the voltage function shape, comparing the electrically controlled birefringence and the Kerr constant in DHF cells with different thickness, driven by STAIR and Step voltage functions.