Photonic engineering of superbroadband near-infrared emission in nanoglass composites containing hybrid metal and dielectric nanocrystals

Photonic media containing hybrid noble metal–dielectric nanocrystals (NCs) represent a wonderland of nanophotonics, with a myriad of uncharted optical functions yet to be explored. Capitalizing on the unique phase separation and spontaneous formation of Au-metal NCs in a gallosilicate glass, we fabricated Ni²+-doped transparent nanoglass composites (GCs) containing Au-metal∕γ-Ga₂O₃-dielectric NCs. Compared with GCs free of Au-metal NCs, the superbroadband near-infrared emission of Ni²+with a full width at half-maximum over 280 nm is enhanced twice in the Au-metal∕γ-Ga₂O₃ dual-phase GCs. A comparison is given as to the spontaneous emission (SPE) properties of Ni² +in the dual-phase GCs when pumped resonantly and off-resonantly with the localized surface plasmon resonance band of the Au-metal NCs. The important role of the Au-metal NCs in the SPE enhancement is revealed by theoretical simulation based on the finite-element method. Combining the photonic engineering effect of hybrid Au-metal∕γ-Ga₂O₃ NCs and the sensitization effect of Yb³+on Ni²+, a record-high enhancement factor of over 10 of the Ni²+NIR emission is achieved, and optical gain is demonstrated in the GCs at the fiber communication wavelength.