Polymer-grafted ZnO nanorods enhance optical nonlinearity of oligothiophene-doped liquid crystals

The photoinduced molecular reorientation of nonlinear optical materials is a promising approach to cause the nonlinear optical effect used for developing next-generation self-modulating and optical switching devices. Liquid crystals (LCs) attract much attention as nonlinear optical materials due to their large change in refractive index and high light sensitivity to induce molecular reorientation. However, the light intensity required to induce molecular reorientation of LC materials is high for optical devices requiring lower threshold intensities. Here, we report a system containing polymer-grafted ZnO nanorods in oligothiophene-doped host LCs able to induce molecular reorientation at lower threshold intensities shown by the formation of concentric diffraction rings. Incorporating 5 wt% of polymer-grafted ZnO nanorods in oligothiophene-doped host LCs significantly reduced the threshold intensity by 39% compared to pure oligothiophene-doped systems. This discovery will provide a new route to use inorganic nanorods in dye-doped host LCs as dopants to enhance the nonlinear optical effect at lower threshold intensities.