Collapse‐Engineered Inverse‐Opal Photonic Microarchitectures Fabricated by Two‐Photon Lithography for Optical Information Encoding

ABSTRACT

Two‐photon lithography (TPL) offers unparalleled geometric freedom for fabricating three‐dimensional micro/nanostructures. However, directly encoding multiple information with vivid structural colors into freeform architectures remains experimentally challenging. Here, we present a hybrid strategy that integrates colloidal self‐assembly with TPL to realize inverse‐opal‐based three‐dimensional microstructures that are simultaneously shape‐programmable, structurally colored, and information‐rich. The key process innovation is a one‐step development protocol in which propylene glycol monomethyl ether acetate concurrently removes both the unpolymerized photoresist and the polystyrene colloidal template, thereby markedly simplifying conventional, time‐intensive workflows. Building on this approach, we fabricate intricate inverse‐opal microarchitectures with vivid coloration governed by the ordered (111) planes of the colloidal crystal. We further exploit freeform three‐dimensional design, focal‐plane selectivity, color multiplexing, and fabrication‐induced stochastic defects to construct microstructures capable of storing multiple layers of information and exhibiting physically unique optical signatures. In addition, we demonstrate that intentionally tilt‐printed structures undergo a reproducible collapse during development and drying that can be deliberately harnessed rather than mitigated. This collapse reorients the crystal lattice with respect to the incident illumination, thereby enabling angle‐selective color readout. This work establishes TPL‐printed 3D inverse opal as a versatile platform for miniaturized structural color devices, anti‐counterfeiting labels, and high‐density optical information carriers.