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

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 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

Upconversion nanocrystals doped glass: A new paradigm for integrated optical glass

© OSA 2016. A new versatile method of integrating upconversion nanocrystals into a glassy matrix is presented, which opens up exciting possibilities for new hybrid glass materials and multifunctional fiber devices with tailored nanoscale properties and high transparency

Single-nanocrystal sensitivity achieved by enhanced upconversion luminescence

Upconversion nanocrystals convert infrared radiation to visible luminescence, and are promising for applications in biodetection1-3, bioimaging4-7, solar cells8-10 and three-dimensional display technologies8,9,11. Although the design of suitable nanocrystals has improved the performance of upconversion nanocrystals10,12-14, their emission brightness is limited by the low doping concentration of activator ions needed to avoid the luminescence quenching that occurs at high concentrations15,16. Here, we demonstrate that high excitation irradiance can alleviate concentration quenching in upconversion luminescence when combined with higher activator concentration, which can be increased from 0.5 mol% to 8 mol% Tm31 in NaYF4. This leads to significantly enhanced luminescence signals, by up to a factor of 70. By using such bright nanocrystals, we demonstrate remote tracking of a single nanocrystal with a microstructured optical-fibre dip sensor. This represents a sensitivity improvement of three orders of magnitude over benchmark nanocrystals such as quantum dots17. © 2013 Macmillan Publishers Limited. All rights reserved