Three-Dimensional Laser Creation of a Near-IR Laser-Gain Medium Based on Hydride Donor/Acceptor Complexes Made of Coupled Laser-Induced Silver Nanoclusters with Ytterbium Ions.

Femtosecond laser inscription in a ytterbium-doped silver-containing phosphate glass is demonstrated by achieving 3D highly localized laser-induced silver photochemistry. The produced fluorescent silver nanoclusters lead to high optical contrast in the visible range, showing that the coinsertion of Yb³⁺ ions is not detrimental to the silver-based photochemistry. We demonstrate efficient energy transfer from these silver nanoclusters to the rare-earth Yb³⁺ ions, leading to near-IR background-free fluorescence emission. Indeed, we demonstrate the 3D-localized near-IR emission of homogeneously distributed Yb³⁺ ions thanks to their spatially selective excitation by colocalized silver nanoclusters. This creation of hybrid donor/acceptor systems, composed of coupled laser-inscribed silver nanoclusters and Yb³⁺ ions, respectively, allows for the 3D-distribubed creation of a laser-active gain medium. The reported effective laser gain results from the silver nanocluster-mediated excitation of the Yb³⁺ lasing ions, demonstrating the energy-transfer-based achievement of inversion population and optically induced transparency of the material. This opens the route for the all-optical fabrication of near-IR micron-scale multiscale architectures compatible with the development of new laser-active media especially for integrated waveguides and active photonic integrated circuits. This includes perspectives of versatile 3D laser-integrated architectures allowing for evanescent coupling under lasing operation with their environment, to achieve enhanced photonic sensing abilities beyond those offered by usual conventional planar of unidirectional architectures.