Interlaced cholesteric liquid crystal fingerprint textures via sequential UV-induced polymer-stabilization

Two types of cholesteric liquid crystal (CLC) fingerprint structures, namely developable-modulation (DM) and growing-modulation (GM), can be contemporaneously prepared in polymer stabilized CLC (PSCLC) composites, to be mutually perpendicular in a repeatable and reversible voltage-switching process when the cell thickness to pitch length ratios (d/P) were appropriately chosen. PSCLC grating structures with interlaced DM/GM fingerprint textures were achieved by varying the applied voltage and sequentially photopolymerizing the dissolved mesogenic monomers through photomasks with stripe and checker patterns. The morphologies of the distinct interlaced PSCLC structures via different UV exposure sequences were investigated under crossed polarizing optical microscopy (POM) and scanning electron microscopy (SEM). The optimized results suggest that DM gratings should be stabilized before GM gratings. Diffraction measurements reveal polarization-dependent properties of the interlaced DM/GM gratings. The intensity redistribution of diffraction orders in orthogonal direction can be achieved by changing the polarization state of incident laser beam. (C) 2015 Optical Society of America