Variation of attenuated total reflection and second harmonic generation of mixed nematic liquid crystals

Optical second harmonic generation from nematic and cholesteric liquid crystals attributing to quadrupole, flexoelectric effect and electric field induced nonlinear susceptibility is detected. The measured second harmonic generation (SHG) intensity is proportional to the square of the applied field irrespective of whether the field is alternate or direct current. The SHG intensity can be enhanced by the surface plasmons generated by attenuated total reflection (ATR) installed by the Kretcshmann-Raether configurations. The small angle shift of the ATR minimum under various change of bias as large as 40 V can be satisfactorily expressed by the three layered system in which the indices of two outer layers retained in their original values by the strong anchoring effect.