Fig. 1. Fabrication and observation process. (a) Utilize TPP to create structures with various shapes, sizes, and periods. (b) Adjust machining settings to control the height and linewidth of the structures. (c) Observe the color under bright-field or cross-polarized illumination modes using a 5× objective lens.

Fig. 2. Results of different structures under cross-polarized illumination. (a) Relationship between the percentage of laser power and the actual power. (b) Simulated transmission spectra of cylindrical arrays, long arrays, cross-shaped arrays, and grating and grid structures under cross-polarized (45°) transmission, where the parameters of the five structures are shown in Table 1. (c)–(g) The left panels are schematic diagrams of the five types of structural arrays and the parameters d, h, p, l; the middle panels are top-view and side-view SEM images of the actual samples corresponding to the structures simulated in (b), where the scale bar in the SEM images represents 1 μm; the right panels show the observation results under transmission when the structure is at 45° to cross-polarization at different powers and periods, where the structures in the green box correspond to the parameters in Table 1. (h) Distribution of electric field intensity and electric field arrows for the grating structure at wavelengths of 520 nm and 740 nm, and the cylindrical structure at wavelengths of 420 nm and 740 nm when the angle of polarization of the incident light is 45°. (i) Simulated transmittance spectra of the five structures in Table 1 at each angle of cross-polarization.

Fig. 3. Results under bright-field illumination for different structures. (a) Scattering and four different poles changes of cylindrical, cross-shaped, asymmetric cross-shaped, and long structures under linearly polarized light sources in the x- and y-directions. (b) Electric field map of light incident for the same structure at wavelengths of 440 nm and 680 nm. Left side of (c)–(g): experimental transmission images for (c) cylindrical arrays, (d) long arrays, (e) grating, (f) cross-shaped arrays, and (g) grids under various powers and periods under bright-field illumination. Middle of (c)–(g): simulated spectra and color corresponding to the fabricated blocks in green box on the left, and the specific experimental parameters are shown in Table 1. Right side of (c)–(g): far-field radiation patterns of the structure in Table 1; the red area is the collection angle of the observation objective.

Fig. 4. Large-scale full-color palettes for cylindrical arrays and grating structures. (a) Simulated transmission spectra for cylindrical arrays with d=600  nm, p=1  μm, and h varying from 0.5 μm to 2.5 μm. (b) Simulated transmission spectra for cylindrical arrays with p=1  μm, h=2  μm, and d ranging from 400 nm to 800 nm. (c) Color representation on the CIE chromaticity diagram for color palette of cylindrical arrays under bright-field illumination in experiment. (d) Transmission results of cylindrical array palette under bright-field illumination at different focus depths. (e) Simulated transmission spectra for cylindrical arrays with d=600  nm, h=1.5  μm, and p ranging from 1 μm to 3.5 μm. (f) Large-scale palettes for cylindrical arrays at an interface relative depth of 0 μm under different powers and periods, where the structures within the gray dashed-line box correspond to cylindrical arrays with diameters around 600 nm. (g) Part of the corresponding SEM images with periodic gradation structures in the solid gray box of large-scale palettes for cylindrical arrays. (h) Palette for gratings at an interface relative focus depth of 0 μm under varying powers and periods.

Fig. 5. Colored and dual patterns. (a) Printed patterns under macroscopic observation. (b) “Cat” color pattern printed with a smaller scanning range for the galvanometer. (c) “Cat” and “Dog” color patterns printed with a larger scanning range for the galvanometer. (d) Partial electron microscope image of “The Starry Night” pattern printed by cylindrical arrays and a grating. (e) “Butterfly” dual pattern printed using a smaller scanning range for the galvanometer, with the hidden part being “NANO”. (f) Part of “The Starry Night” color pattern printed using a smaller scanning range for the galvanometer. (g) “The Starry Night” dual pattern printed under a larger scanning range for the galvanometer, showing the results under bright-field transmission illumination. (h) Hidden pattern of “The Starry Night” revealed under cross-polarized transmission illumination: “2023” printed using a grating, with the remaining parts printed using cylindrical arrays.

Fig. 6. Large-scale patterns printed on a silicon wafer. (a) Cylindrical arrays of different substrates are used to simulate the electric field and far-field radiation at 720 nm. (b) Schematic of observation angles: angle a is the elevation angle, angle b is the azimuth. (c) The large-scale pattern exhibits different colors when viewed from various angles. (d) SEM images of cylindrical arrays at a 45° oblique angle: top left with a diameter of 330 nm and a period of 620 nm; bottom left with a diameter of 150 nm and a period of 350 nm; top right with a diameter of 600 nm and a period of 2.1 μm; bottom right with a diameter of 450 nm and a period of 1.2 μm. (e) This angle allows for the observation of the company’s name in both Chinese and English on the sample. (e) When illuminated with intense light, hidden parts of the text on the sample become visible.