3D Imprinting of Voxel‐Level Structural Colors in Lithium Niobate Crystal

Abstract Advanced coloration methods are of pivotal importance in science, technology, and engineering. However, 3D structural colors that are critical for emerging multidimensional information representation and recording are rarely achievable. Here, a facile voxel‐level programmable 3D structural coloration in the bulk lithium niobate (LiNbO 3 ) crystal is reported. This is achieved by engineering wavelength‐selective interference between ordinary (O) and extraordinary (E) light in the crystal matrix. To induce effective phase contrast between O and E light for establishing the highly localized interference across the visible band, the presence of a pulse‐internal‐coupling effect is revealed in the single‐pulse ultrafast laser–crystal interaction and an ultrafast‐laser‐induced micro‐amorphization (MA) strategy is thus developed to manipulate local matrix structure. Consequently, micro–nanoscale colorful voxels can be fast inscribed into any spatial position of the crystal matrix in one step. It is demonstrated that the colors can be flexibly manipulated and quickly extracted in 3D space. Multidimensional MA‐color data storage with large capacity, high writing and readout speed, long lifetime, and excellent stability under harsh conditions is achieved. The present principle enables multifunctional 3D structural coloration devices inside high‐refractive‐index transparent dielectrics and can serve as a general platform to innovate next‐generation information optics.