A low-loss optical waveguide from a 1D europium nanocluster

The rational engineering of material properties and spatial arrangements enabling micro–nano-optical waveguides is crucial for realizing photonic integration and particularly for processing ultracompact optical signal platforms. Rare-earth ions have narrow-band emission and long excited-state lifetimes stemming from stable 4f energy-level structures, which enable extremely low non-uniform linewidths and very small spectral spreads to achieve high-resolution and high-fidelity optical signal transmission in waveguides. Herein, we reported a low-loss optical waveguide with a coefficient of 6.4 × 10−3 dB μm−1 from the electric dipole 5D0 → 7F2 transition in one-dimensional europium nanoclusters, the minimum value for rare earth-based materials. The structural orientations and luminescence performance associated with optical waveguides have also been explored in depth. The effectively directed photon transport makes lanthanide-based metal nanoclusters promising candidates for active photonic elements.