RESUMO
Metasurfaces supporting optical bound states in the continuum (BICs) are emerging as simple and compact optical cavities to realize polarization-vortex lasers. The winding of the polarization around the singularity defines topological charges which are generally set by the cavity design and cannot be altered without changing geometrical parameters. Here, a subwavelength-thin phase-change halide perovskite BIC metasurface functioning as a tunable polarization vortex microlaser is demonstrated. Upon the perovskite structural phase transitions, both its refractive index and gain vary substantially, inducing reversible and bistable switching between distinct polarization vortexes underpinned by opposite topological charges. Dynamic tuning and switching of the resulting vector beams may find use in microscopy imaging, particle trapping and manipulation, and optical data storage.
RESUMO
It remains a challenge to directly print arbitrary three-dimensional shapes that exhibit structural colors at the micrometer scale. Woodpile photonic crystals (WPCs) fabricated via two-photon lithography (TPL) are elementary building blocks to produce 3D geometries that generate structural colors due to their ability to exhibit either omnidirectional or anisotropic photonic stop bands. However, existing approaches produce structural colors on WPCs when illuminating from the top, requiring print resolutions beyond the limit of commercial TPL, which necessitates postprocessing techniques. Here, we devised a strategy to support high-order photonic cavity modes upon side illumination on WPCs that surprisingly generate prominent reflectance peaks in the visible spectrum. Based on that, we demonstrate one-step printing of 3D photonic structural colors without requiring postprocessing or subwavelength features. Vivid colors with reflectance peaks exhibiting a full width at half-maximum of â¼25 nm, a maximum reflectance of 50%, a gamut of â¼85% of sRGB, and large viewing angles were achieved. In addition, we also demonstrated voxel-level manipulation and control of colors in arbitrary-shaped 3D objects constituted with WPCs as unit cells, which has potential for applications in dynamic color displays, colorimetric sensing, anti-counterfeiting, and light-matter interaction platforms.
