Structural Color\nfrom Multi-Bounce Reflection Interference\nin Metalized Microstructures

The development of materials and\nmethods for controlling\niridescent\nstructural color arising from optical interference has attracted considerable\nattention for a variety of applications ranging from anticounterfeiting\nto displays. Here, we investigate high-reflectivity structural color\ngenerated by multi-bounce reflection interference within metallized\nmicrostructures and describe the relationships between coloration,\nreflection efficiency, and microstructure geometry. Ray tracing simulations\nare combined with experimental, angularly resolved far-field optical\nanalysis for a detailed understanding of the underlying mechanism.\nFabrication of microstructures with grayscale lithography and image\npatterning using metal masking is demonstrated. We further investigate\nmicrostructure geometries combining both concave and convex curvatures\nfor highly diversified and more complex tunable optical interference.\nThese results provide insight into how to control the iridescent properties\nof microstructures with improved structural color saturation and reflectivity\nby exploiting a multi-bounce interference optical mechanism.