In situ dopant-induced nano-crystallization of rare-earth-fluoride crystals in phase-separated networks for highly-efficient photoemission and photonic devices

Oxy-fluoride nano-crystallized glass-ceramics (NGCs), with integrated advantages of amorphous glasses and fluoride crystals, show great potential for applications in lighting, information storage and lasers. However, the photoluminescence quantum yields (PLQYs) of traditional NGCs are restricted by the difficulty in the incorporation of the number of active ions into crystal structures due to the mismatch of the radius in the ionic substitution process. Herein, an in situ dopant-induced nano-crystallization strategy is proposed for the design and fabrication of NGCs with high PLQY. The strategy is suitable the precipitation of all kinds of rare-earth-fluoride nanocrystals in glasses and thus dramatically enhances the PL efficiency in upconversion and down-shifting emission. The upconversion PLQY of designed NGCs (2.77%) is 3 times larger than that of well-established NGC containing beta-NaYF4 crystals (0.78%), which have widely been considered the most efficient NGC for upconversion luminescence. Moreover, the designed NGCs also exhibit higher optical transmittance and PL behaviors show more excellent photo-thermal stability, in comparison with that of traditional NGCs. Most importantly, low-threshold, high-slope-efficiency microsphere lasers have been successfully demonstrated by leveraging our well-designed NGCs. This strategy opens a new avenue for the design and fabrication of highly efficient optical gain micro-/nanomaterials for applications in emerging photonics devices.