Influence of linearly varying pretilt patterns on nematic liquid crystal orientation for planar optics

Abstract This study provides design insights for liquid crystal planar optics (LCPO) by investigating how spatially varying pretilt angles affect liquid crystal (LC) orientation in the bulk. A cell with homeotropic alignment on one surface and a linear pretilt distribution from 0° to 90° on the opposite surface was analyzed using nematic LC continuum theory. The simulation results revealed that the LC director exhibits splay deformation, in which the strength of deformation corresponds with the pretilt angle. The retardation profile depends on the ratio between the cell thickness and the pretilt pattern period: when the period exceeds ten times the cell thickness, the retardation profile becomes sufficiently linear, which is crucial for high-efficiency wavefront modulation in diffractive optical elements. This knowledge offers essential design guidelines for compact, tunable, and high-performance LC-based optical devices.