Inorganic Nanorods Enable the Memorization of Photoinduced Microlens Arrays in Dye-Doped Liquid Crystals.

The photoinduced molecular reorientation of liquid crystals (LCs) caused by their nonlinear optical responses has attracted much attention due to their large refractive index change, leading to promising applications in optical devices. This reorientation is typically induced by light irradiation above a threshold intensity and is temporary, with the initial orientation recovering unless the LCs are polymerized and cross-linked. Our report highlights the memory effect of molecular reorientation in LCs. The high-intensity laser beam irradiation of dye-doped LCs containing polymer-grafted ZnO nanorods resulted in the molecular reorientation of the LCs. The effect was maintained even after the light was turned off. This memorized molecular orientation functioned as a polarization-dependent microlens due to the self-phase modulation and self-focusing effect of the propagating light. The polarization selectivity of the microlens allows for innovative optical applications, including security printing and anticounterfeiting.