Defect Engineering Enabled Multimodal Dynamic Optical Responses in Tb 3+ ‐Doped Ca 2 GdGa 3 Ge 2 O 12 Garnet for Advanced Anti‐Counterfeiting

ABSTRACT Traditional static, single‐mode optical materials struggle to meet the growing demands of high‐security anti‐counterfeiting. Developing multimodal optical response (MOR) materials that integrate dynamic color‐changing capabilities with multiple stimuli‐responsive luminescence modes remains a significant challenge. Herein, we introduce Tb 3+ into the defect‐rich self‐activated host Ca 2 GdGa 3 Ge 2 O 12 (CGGGO) to address this issue. By tuning the doping concentration and temperature, photoluminescence (PL) is continuously tuned from blue to green. Through trap reconstruction, Tb 3+ doping not only introduces efficient luminescent centers but also significantly enhances defect‐related optical performance, enabling long persistent luminescence (PersL, >10 h), photo‐stimulated luminescence (PSL), and thermally stimulated luminescence (TSL). Furthermore, both the host and Tb 3+ ‐doped samples exhibit reversible photochromism (PC) with distinct color changes under 254 nm irradiation, driven by oxygen‐vacancy‐mediated charge trapping and detrapping. Through the synergistic integration of PL, PersL, PSL, TSL, and reversible PC, we construct an anti‐counterfeiting label with multidimensional modulation capabilities. This label enables high‐security optical information readout across spatial, temporal, and stimulus dimensions, providing a new platform for advanced anti‐counterfeiting and optical information encryption.