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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 (Y 2 O 3 ). 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 Y 2 O 3 polycrystalline ceramic host matrix, we observe charging pathways via the inter-band optical absorption of Y 2 O 3 and via the 4f-5d transitions of Pr 3+ . We demonstrate effective control of the density of trapped charges within the Y 2 O 3 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.
To collect OSL emission spectra, the optical fiber delivering the stimulation laser was placed in parallel to the initial UV beam and facing the sample (top panel, not shown). TL measurements were performed with a setup that comprises a custom-made heating system, i.e., a ceramic heater with a PID temperature controller, and a PMT (300–650 nm range, H11870-01 model, Hamamatsu) connected to the photon counter. Besides reporting an all-optical control approach of localized charging environment, this work offers a tool to probe possible interactions between intrinsic defects and luminescence centers in the host matrix.
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