Adaptive Gradient-Index Optics via Liquid Crystals on UV-Treated Polyimide Layer with Programmable Pretilt Pattern

Patterned surface conditions designed through self-organization at the environmental interface of soft matter systems, such as liquid crystals (LCs), are critically important for advancing engineering applications. In this study, we develop a fabrication method and experimentally demonstrate adaptive gradient refractive index optics, using by LCs aligned on ultraviolet (UV)-irradiated polyimide films with a programmable pretilt pattern. To verify the Friedel–Creagh–Kmetz (FCK) rule, which states that the pretilt angle of LCs dep-ends on the surface free energy of the substrate, we evaluated the surface free energy of UV-irradiated polyimide films, breaking it down into each component of intermolecular interaction. The results suggest that the polar component of the intermolecular interaction in the alignment layer plays a key role in determining the pretilt angle. We successfully demonstrated the formation of distinct linear and periodic retardation distributions by spatially controlling the UV irradiation time using a slit mask. The linearity of the retardation profile is preserved under the applied voltage. Furthermore, we demonstrated that the transmitted light is deflected by the LC device and that the diffraction angle can be electrically controlled. These results pave the way for the development of electrically tunable flat optics capable of real-time spatial modulation and mechano-free operation.