Maskless Ultraviolet Grayscale Lithography for Fabry-Pérot Cavity Color Printing with Post-Exposure Bleaching

The existing maskless grayscale lithography for Fabry-Pérot (F-P) cavity structural colors relies on point-by-point direct writing lithography, which suffers from low efficiency. We present a maskless ultraviolet (UV) grayscale lithography approach for printing F-P cavitybased structural color. The approach precisely modulates resist thickness in parallel via grayscale control and introduces a 405 nm UV post-exposure bleaching step to reduce absorption and enhance refractive index. Optimized F-P cavities achieve reflectance above 93 % and produce vivid, high-saturation colors. Simulation and experimental results confirm a clear correlation among exposure grayscale, residual resist thickness, and the color output. The proposed technique offers a high-throughput, costeffective route for large-area, high-resolution color printing with potential applications in anti-counterfeiting label, display and optical encoding.