Dynamic Tuning of Fabry-Pérot Resonances Based on Femtosecond Laser-Induced Structure-Property Integrated Regulation

Structural colors based on micro/nano fabrication technologies can customize optical responses to generate colors, achieving optical camouflage. However, dynamic camouflage that provides a wide range of color switching to match changing environments remains a daunting challenge. Here, we propose a structure-property integrated regulation method of dual-wavelength fs laser switching output, further regulate the F-P resonance, and eventually achieve wide-range and reversible color tuning. Specifically, the asymmetric Fabry-Pérot (F-P) cavity is composed of air layer, an antimony disulfide (Sb₂S₃) active dielectric layer, and an Al metal layer. By using 1030 and 515 nm fs lasers to regulate the thickness and phase state of the Sb₂S₃ film, F-P resonances are dynamically tuned. The 1030 nm fs laser can precisely remove the Sb₂S₃ film, achieving an average height difference of ∼2 nm. Due to the wide bandgap of ∼2.0 eV in Sb₂S₃, there are significant differences in the ability of a fs laser with different wavelengths to induce phase changes. Utilizing the 515 nm fs laser to match the wide bandgap, the crystallization and reversible phase change of Sb₂S₃ induced by only fs laser are achieved for the first time. Based on the physical morphological changes and phase change of Sb₂S₃, the color tuning range is effectively expanded to 71.4% sRGB, and reversible color tuning is achieved. By introducing grating dispersion responses through laser-induced periodic surface structures, the color tuning range is further expanded to 106.7% sRGB. After F-P cavities are fabricated, the fs laser and thermal annealing can still be used to further switch colors.