Phase-Change Perovskite Microlaser with Tunable Polarization Vortex.

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.

High-Order Photonic Cavity Modes Enabled 3D Structural Colors.

It remains a challenge to directly print arbitrary three-dimensional shapes that exhibit structural colors at the micrometer scale. Woodpile photonic crystals (WPCs) fabricated 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.