An experimental investigation and the optical modeling of the structural coloration produced from total internal reflection interference within 3D microstructures are described. Ray‐tracing simulations coupled with color visualization and spectral analysis techniques are used to model, examine, and rationalize the iridescence generated for a range of microgeometries, including hemicylinders and truncated hemispheres, under varying illumination conditions. An approach to deconstruct the observed iridescence and complex far‐field spectral features into its elementary components and systematically link them to ray trajectories that emanate from the illuminated microstructures is demonstrated. The results are compared with experiments, wherein microstructures are fabricated with methods such as chemical etching, multiphoton lithography, and grayscale lithography. Microstructure arrays patterned on surfaces with varying orientation and size lead to unique color‐traveling optical effects and highlight opportunities for how total internal reflection interference can be used to create customizable reflective iridescence. The findings herein provide a robust conceptual framework for rationalizing this multibounce interference mechanism and establish approaches for characterizing and tailoring the optical and iridescent properties of microstructured surfaces.

Here, structural color generated by total internal reflection (TIR) interference at microscale concave interfaces is tuned via evanescent wave absorption by dyes. Using quantitative angle-resolved spectral analysis combined with ray tracing simulation, it is demonstrated that the multibounce TIR trajectories enhance the efficiency of dye absorption and usefulness in modulating the reflected colors. Depending on the absorbance spectrum of the dye used, and the amount of dye coated at the TIR interface, the angle-dependent reflected colors can be predictably altered. The use of a near-infrared absorbing dye allows for the combination of overt color-shifting iridescent effects under illumination with visible wavelengths and covert optical-motion effects under near-infrared. This work, which explores an innovative approach for controlling the reflective properties of iridescent structurally colored materials, may be of interest both for fundamental research and for applications such as sensors, coatings, and security.

This report describes the experimental investigation and optical modeling of the structural coloration produced from total internal reflection interference within 3D microstructures. Ray tracing simulations coupled with color visualization and spectral analysis techniques are used to model, examine, and rationalize the iridescence generated for a range of micro-geometries, including hemicylinders and truncated hemispheres, under varying illumination conditions. An approach to deconstruct the observed iridescence and complex far-field spectral features into its elementary components and systematically link them to ray trajectories that emanate from the illuminated microstructures is demonstrated. The results are compared with experiments, wherein microstructures are fabricated with methods such as chemical etching, multiphoton lithography, and greyscale lithography. Microstructure arrays patterned on surfaces with varying orientation and size lead to unique color-traveling optical effects and highlight opportunities for how total internal reflection interference can be used to create customizable reflective iridescence. The findings herein provide a robust conceptual framework for rationalizing this multibounce interference mechanism and establish approaches for characterizing and tailoring the optical and iridescent properties of microstructured surfaces.

Reflected coloration can be generated in microtextured materials via multipath total internal reflection interference. Here, the reflected iridescent coloration is tuned through the dye absorption of the evanescent wave that is generated at the optical interface upon total internal reflection. Using quantitative angle-resolved spectral analysis combined with a ray tracing simulation, it is demonstrated that the multibounce total internal reflection trajectories enhance the efficiency of dye absorption and the usefulness in modulating the reflected colors. Depending on the absorbance spectrum of the dye used and the amount of dye coated on the optical interface, the angle-dependent reflected colors can be predictably altered. The use of a near-infrared absorbing dye allows for the combination of overt color-shifting iridescent effects under illumination with visible wavelengths and covert optical-motion effects under near-infrared wavelengths. This work, which explores an innovative approach for controlling the reflective properties of iridescent, structurally colored materials, has relevance both for fundamental research and for applications such as sensors, coatings, and security.

Here, structural color generated by total internal reflection (TIR) interference at microscale concave interfaces is tuned via evanescent wave absorption by dyes. Using quantitative angle-resolved spectral analysis combined with ray tracing simulation, it is demonstrated that the multibounce TIR trajectories enhance the efficiency of dye absorption and usefulness in modulating the reflected colors. Depending on the absorbance spectrum of the dye used, and the amount of dye coated at the TIR interface, the angle-dependent reflected colors can be predictably altered. The use of a near-infrared absorbing dye allows for the combination of overt color-shifting iridescent effects under illumination with visible wavelengths and covert optical-motion effects under near-infrared. This work, which explores an innovative approach for controlling the reflective properties of iridescent structurally colored materials, may be of interest both for fundamental research and for applications such as sensors, coatings, and security.