Thermally Switchable Multicolor Glow in a Chameleon Phosphor for Secure Multi‐Level Optical Data Storage

ABSTRACT The integration of electron‐trapping phosphors into optical data storage is revolutionizing the information technology landscape. While promising, progress has been hindered by challenges in reliably reading phosphor‐based signals, primarily due to the lack of secure, multi‐level data‐retrieval techniques. Here, we address these issues by developing a “chameleon” phosphor platform, Y 3 Ga 5 O 12 garnet co‐doped with Pr 3+ and Tb 3+ ions, that exhibits a multicolor glow capable of being thermally switched, enabling layered, high‐security data extraction. Using a commercial 450 nm laser for up‐conversion charging, we achieve rapid data writing across distinct trap depths. The critical aspect of our approach lies in the retrieval process: via temperature‐gated energy transfer, the emission color shifts from a bluish‐purple (dominated by Tb 3+ ) to a deep red (dominated by Pr 3+ ). This design overcomes the limitations of fixed‐channel storage by providing three distinct access tiers, all while ensuring repeatable readout without degradation over extended periods. Our findings offer insights into trap dynamics and energy transfer, paving the way for practical optical storage solutions and marking a significant step forward in the evolution of next‐generation information systems.