All-optical control of charge-trapping defects in rare-earth doped oxides

Charge-trapping defects in crystalline solids play important roles in applications ranging from microelectronics, optical storage, sensing and quantum technologies. On one hand, depleting trapped charges in the host matrix reduces charge noise and enhances coherence of solid-state quantum emitters. On the other hand, stable charge traps can enable high-density optical storage systems. Here we report all-optical control of charge-trapping defects via optical charge trapping (OCT) spectroscopy of a rare-earth ion doped oxide (Y₂O₃). Charge trapping is realized by low intensity optical excitation in the 200-375 nm range. Charge detrapping or depletion is carried out by optically stimulated luminescence (OSL) under 532 nm stimulation. Using a Pr-doped Y₂O₃ polycrystalline ceramic host matrix, we observe charging pathways via the inter-band optical absorption of Y₂O₃ and via the 4f-5d transitions of Pr³⁺. We demonstrate effective control of the density of trapped charges within the Y₂O₃ matrix at ambient environment. These results point to a viable method for controlling the local charge environment in rare-earth doped crystals via all-optical means, and pave the way for further development of efficient optical storage technologies with ultrahigh storage capacity, as well as for the localized control of quantum coherence in rare-earth doped solids.