Optical diode effect of nematic liquid crystal induced by plasma-treated surface

We reported an optical diode effect of a nematic liquid crystal (LC) sample induced by a plasma-treated surface. The LC sample whose one of the substrates was plasma treated transmitted or blocked the incident light depending on the sign of the applied electric field. On the other hand, the LC samples whose both substrates were plasma treated or none of the substrates were plasma treated showed the same transmittance regardless of the sign of the electric field. The optical diode effect was shown when the nematic LC materials contain strong dipole moments, while the same effect was not observed when the weak polar LC was used. A thin polar LC layer formed near the plasma-treated surface makes the net field in the positive and the negative frame to be different, resulting in the optical diode effect.