Circularly polarized optical imprinting for robust fabrication of geometric-phase diffraction gratings

We systematically investigate the influence of polarization conditions on the robustness of optical imprinting using liquid-crystal geometric-phase (GP) masks in the presence of retardation errors. Jones analysis reveals that retardation errors of GP masks predominantly affect the ellipticity rather than the polarization azimuth in the case of linear polarization incidence. In contrast, circularly polarized illumination preserves a well-defined polarization azimuth associated with the GP even under nonideal retardation conditions. These theoretical predictions are experimentally demonstrated. This result establishes circularly polarized optical imprinting as an intrinsically robust approach for practical fabrication of high-quality GP diffractive elements.