Inorganic\nNanorods Enable the Memorization of Photoinduced\nMicrolens Arrays in Dye-Doped Liquid Crystals

The photoinduced\nmolecular reorientation of liquid crystals (LCs)\ncaused by their nonlinear optical responses has attracted much attention\ndue to their large refractive index change, leading to promising applications\nin optical devices. This reorientation is typically induced by light\nirradiation above a threshold intensity and is temporary, with the\ninitial orientation recovering unless the LCs are polymerized and\ncross-linked. Our report highlights the memory effect of molecular\nreorientation in LCs. The high-intensity laser beam irradiation of\ndye-doped LCs containing polymer-grafted ZnO nanorods resulted in\nthe molecular reorientation of the LCs. The effect was maintained\neven after the light was turned off. This memorized molecular orientation\nfunctioned as a polarization-dependent microlens due to the self-phase\nmodulation and self-focusing effect of the propagating light. The\npolarization selectivity of the microlens allows for innovative optical\napplications, including security printing and anticounterfeiting.