Three‐Dimensional Photoengraving of Monolithic, Multifaceted Metasurfaces

Abstract

Metasurfaces present a potent platform to manipulate light by the spatial arrangement of sub‐wavelength patterns with well‐defined sizes and geometries, in thin films. Metasurfaces by definition are planar. However, it would be highly desirable to integrate metasurfaces with diverse, spatially programmed sub‐wavelength features into a 3D monolith, to manipulate light within a compact 3D space. Here, a 3D photoengraving strategy is presented; that is, generation of such composite metasurfaces from a single microstructure via the irradiation of multiple interference laser beams onto different facets of the parent azopolymeric microstructure. Through “photofluidization,” this technique enables independent inscription and erasing of metasurfaces onto and from individual facets of 3D monoliths with arbitrary shapes and dimensions, in a high‐throughput fashion (over approximately a few cm2 at a time). By engraving discrete sub‐wavelength 1D surface relief gratings of different pitches on different facets of an inverse pyramidal array, a multiplexing structure‐color filter is demonstrated.

Homeostatic growth of dynamic covalent polymer network toward ultrafast direct soft lithography

“…4B ). Our approach of creating structural colored patterns is notably simpler and more flexible than existing methods ( 22 , 23 ). Since the homeostatic growth mechanism does not require a spin-coating of a photoresist layer as conventional photolithography does, it can be, in principle, applied to complex nonplanar surfaces.…”

Fabrication and applications of stimuli‐responsive micro/nanopillar arrays

“…Under light exposure, azobenzene derivatives undergo photoisomerization between trans-and cis-isomers. 72,143 Polymers with grafted azobenzene groups can generate light-induced mass migration from light exposure. 144 Polarized light induces repetitive photoisomerization of azobenzene groups that are in phase with the direction of polarization.…”

“…Under light exposure, azobenzene derivatives undergo photoisomerization between trans‐ and cis‐ isomers 72,143 . Polymers with grafted azobenzene groups can generate light‐induced mass migration from light exposure 144 .…”

Mechanically Guided Hierarchical Assembly of 3D Mesostructures

“…Such architectures support essential functions in both plant and animal life, such as flower stamens and petals for pollination, gecko's feet for controlled adhesion, and shark scales for drag reduction. These and other examples of 3D systems in living organisms also provide inspiration for engineered counterparts in electronics, [1][2][3][4][5] photonics, [6][7][8][9] biosensing, [10][11][12][13] energy storage systems, [14][15][16][17] mechanical and optical metamaterials, [18][19][20][21][22][23] microrobotics, [24][25][26][27][28][29] and other areas. Schemes for fabricating such structures focus on direct top-down or bottom-up techniques.…”