On-Demand Control of Lanthanide Optical Dynamics via Pumping-Flux Modulation

Precise control of lanthanide luminescence decay is essential for the development of emerging nanophotonic applications. However, existing strategies rely on static material modifications. Here, we introduce a pumping-flux modulation strategy that enables reversible, on-demand tuning of luminescence lifetimes via direct control of the cross-relaxation processes. Using highly Er³⁺-doped nanocrystals, we demonstrate that adjusting excitation pulse duration and intensity enables over 10-fold tuning in green (from 47.3 to 537.1 μs) and near-infrared (1506.4 to 145.5 μs) emissions. Mechanistic studies reveal that excitation profile modulation alters the populations of ground and intermediate energy states, which, in turn, influences cross-relaxation pathways and emission kinetics. We further demonstrate dynamically programmable lifetime mapping for optical encryption, eliminating the need for complex materials engineering. This work introduces a fundamentally new route for controlling lanthanide emission in real time with broad implications for adaptive displays, reconfigurable photonics, and time-domain optical security.