On-Crystal Spectral Modulator from Polarized Propagation of Lanthanide-Titanium Nanoclusters.

The orientation and magnitude of optical polarization in trivalent lanthanides (Ln3+) depend on the directional arrangement of individual transition dipole moments (TDMs), rendering great difficulty in achieving polarized propagation that is highly determined by the packing symmetry and the compositional coordination in atomic precision. Here, we obtained crystals of the organic-monolayer protected titanium-alloyed lanthanide nanoclusters (i.e., Eu8Ti10 NCs), where the TDMs of Eu3+ ions generate typically orthogonal polarization behaviors (i.e., π/σ-light) from the 5D0 → 7F1,2 transition. Importantly, the Eu8Ti10 single crystal exhibits polarized propagation with significant anisotropy relative to the crystallographic axis, which enables spectral modulation directly on the crystal.