"Universal visible emitters in nanoscale integrated photonics" (2023) https://opg.optica.org/optica/fulltext.cfm?uri=optica-10-7-8... :

Visible wavelengths of light control the quantum matter of atoms and molecules and are foundational for quantum technologies, including computers, sensors, and clocks. The development of visible integrated photonics opens the possibility for scalable circuits with complex functionalities, advancing both science and technology frontiers. We experimentally demonstrate an inverse design approach based on the superposition of guided mode sources, allowing the generation and complete control of free-space radiation directly from within a single 150 nm layer Ta2O5 , showing low loss across visible and near-infrared spectra. We generate diverging circularly polarized beams at the challenging 461 nm wavelength that can be directly used for magneto-optical traps of strontium atoms, constituting a fundamental building block for a range of atomic-physics-based quantum technologies. Our generated topological vortex beams and the potential for spatially varying polarization emitters could open unexplored light–matter interaction pathways, enabling a broad new photonic–atomic paradigm. Our platform highlights the generalizability of nanoscale devices for visible-laser emission and will be critical for scaling quantum technologies.