Spectral hole burning quantum efficiency and electron traps in Sm2+-ion-doped aluminosilicate glasses

Persistent spectral hole burning (PSHB) in the F-7(0)-D-5(0) transition and the electron excitation in the F-7(0)-4f5d transition of Sm2+ doped in Al2 O3-SiO2 glasses were studied from the measurements of hole burning efficien cy and the refilling of the burnt hole. The PSHB at low temperature is attr ibuted to the optically activated rearrangement of OH bonds surrounding Sm2 + ions. On the other hand, the PSHB at high temperature is attributed to on e-step electron tunneling in the excitation state. The barrier heights for hole filling corresponding to the two mechanisms were determined to be simi lar to 0.27 and similar to 0.90 eV, respectively. Thermal depth of the trap that captures electrons by two-step ionization via the 4f5d state was dete rmined to be similar to 0.35 eV below the conduction band. A model was prop osed for describing the PSHB and electron excitation of Sm2+ doped in Al2O3 -SiO2 glasses. In addition, the dependence of hole burning efficiency on th e Al2O3 concentration, temperature, and burning wavelength was also studied . [S0163-1829(99)05917-2].