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 → ⁷F_1,2 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.