Upconversion Nanocrystal‐Doped Glass: A New Paradigm for Photonic Materials

The integration of novel luminescent nanomaterials into glassy matrix can lead to new hybrid materials and photonic devices with promising material performance and device functions. Lanthanide‐containing upconversion nanocrystals have become unique candidates for sensing, bioimaging, photon energy management, volumetric displays, and other photonic applications. Here, a versatile direct‐doping approach is developed to integrate bright upconversion nanocrystals in tellurite glass with tailored nanoscale properties. Following our two‐temperature glass‐melting technique, the doping temperature window of 550–625 °C and a 5 min dwell time at 577 °C are determined as the key to success, which balances the survival and dispersion of upconversion nanocrystals in glass. It is identified that the fine spectra of upconversion emissions can be used to diagnose the survival and dissolution fraction of doped nanocrystals in the glass. Moreover, 3D dispersion of nanocrystals in the glass is visualized by upconversion scanning confocal microscopy. It is further demonstrated that a low‐loss fiber, drawn from the highly transparent nanocrystals‐doped glass retains the distinct optical properties of upconversion nanocrystals. These results suggest a robust strategy for fabrication of high‐quality upconversion nanocrystal‐doped glasses. The new class of hybrid glasses allows for fiber‐based devices to be developed for photonic applications or as a useful tool for tailoring light–nanoparticles interactions study.