Unlocking deep-trap data: Photonically engineered trap transfer strategy for secure phosphor memory

Secure, repeatable access to information stored in deep electron traps remains the central barrier to realizing the full potential of electron-trapping phosphors in next-generation optical memory. Existing readout methods typically rely on destructive thermal or nonselective optical stimulation, which limits repeated access and compromises data integrity. Here, we introduce photonically engineered trap transfer (PETT), a heat-free, nonvolatile approach enabling selective data extraction from deep traps. A specially designed garnet phosphor, $\mathrm{G}{\mathrm{d}}_{3}\mathrm{G}{\mathrm{a}}_{5}{\mathrm{O}}_{12}$ codoped with $\mathrm{C}{\mathrm{r}}^{3+}$ and $\mathrm{E}{\mathrm{u}}^{3+}$, serves as the storage medium, with $\mathrm{C}{\mathrm{r}}^{3+}$ acting as the luminescent center and $\mathrm{E}{\mathrm{u}}^{3+}$ engineering a hierarchical trap landscape. Data writing is achieved through an up-conversion charging process that embeds data within 0.01 s. In the PETT readout, visible light transfers electrons from deep to shallow traps; subsequent infrared stimulation releases them, producing a detectable luminescence signal. Kinetic modeling of the PETT process describes the time evolution of the shallow-trap population and reveals its characteristic rise-and-decay behavior. This method provides a reliable, selective, and repeatable route to data retrieval and establishes a robust physical framework for secure, multilevel, rewritable optical memory.