ions coupled to hyperbolic metamaterials*

We investigate a system comprising of Eu³⁺(NO₃)₃ nanocrystals on a hyperbolic metamaterial (HMM) structure featuring a hexagonal array of Ag-nanowires in a porous Al₂O₃ matrix. HMM-coupled Eu³⁺ ions exhibit up to 2.4-fold increase of their decay rate, accompanied by an enhancement of its ⁵D₀→⁷F₂ transition emission rate. Using FD-TD modeling, we corroborate these observations with the increase in the photonic density of states seen by the Eu³⁺ ions in the proximity of the HMM. Our results indicate HMMs can serve as a valuable tool to control the emission from weak transitions, and hence hint at a route towards more practical applications of rare-earth ions in nanoscale sensing and optoelectronic devices.

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