Fig. 1. Schematic diagram of the working principle of the color printing by using pixelated F–P cavities. The F–P cavity consists of a silver (Ag)/PR/silver (Ag) sandwich structure. The spatially variant thickness of the PR layer is realized through the laser grayscale lithography process. Under the illumination of a white light source, the colorful image with a micron-scale spatial resolution can be obtained.

Fig. 2. Calculated optical responses of the silver (Ag)/PR/silver (Ag) F–P cavities. (a) The cross-section of the F–P cavity. The silver film with a thickness of 30 nm and the PR layer serve as the mirror and the spacer of the F–P cavity, respectively. The F–P cavity sitting on the glass substrate is encapsulated by a 20-nm-thick SiO2 layer to avoid the oxidation of the silver layer. (b) Transmission spectra of the F–P cavities working at red (630 nm), green (530 nm), and blue (452 nm) wavelengths; the corresponding cavity lengths are 138, 105, and 79 nm, respectively. (c) The transmission efficiency as a function of spacer thickness and wavelength is plotted. (d) The calculated transmission colors labeled with black circles are mapped in the CIE 1931 chromaticity diagram.

Fig. 3. Optical properties of the color palettes. (a) Under the illumination of a halogen lamp, the white-balanced photos of the color palettes are taken by using a commercial camera. L is the retrieved effective length of the PR layer. The scale bar is 50μm. (b) Measured transmission spectra of the color palettes in which the PR layers have different thicknesses. The colors of lines are corresponded to (a). (c) The measured transmission colors (black circles) are mapped in the CIE 1931 chromaticity diagram.

Fig. 4. Centimeter scale color printing with the pixelated F–P cavities. (a) The grayscale figure is converted from the original drawing. (b) Under the illumination of a halogen lamp, the white balanced photo of the centimeter scale color printing device. (c) and (d) The microscopy images of the regions R1 and R2, which are shown by the white dashed box in (b). (e) and (f) The 3D profiles of the regions R1 and R2, which are measured by using a white light interferometer. The scale bars in (a) and (b) are 1 mm. The scale bars in (c), (d), (e), and (f) are 200μm.

Fig. 5. The microscopy images of the color filter arrays made of pixelated F–P cavities. (a)–(d) The working wavelengths of the four kinds of color filters are 669 nm (red), 591 nm (yellow), 545 nm (green), and 468 nm (blue). The pixel sizes in (a)–(d) are 30μm×30μm, 20μm×20μm, 10μm×10μm, and 5μm×5μm, respectively. Scale bar: 50μm.