The mechanism for highly efficient photoionization spectral hole burning in the 4f<sup>7</sup>–4f<sup>6</sup>5d<sup>1</sup> transition of Eu<sup>2+</sup> in MgS host is investigated in detail. The time and power dependencies of the hole depth and its photoerasure are analyzed assuming that a resonant two-photon ionization process initiates the hole burning. The near-room-temperature cycling shifts the hole to low energies, demonstrating the relaxation of an unstable lattice resulting from the hole burning. The characteristics of hole burning change significantly in samples codoped with Ce and Eu. All of these studies support that the mechanism of hole burning is the electron transfer from the Eu<sup>2+</sup> ion to the Eu<sup>3+</sup> deep trap, both of which are located at the substitutional octahedral sites.
© 2001 Optical Society of America
(160.4760) Materials : Optical properties
(210.4810) Optical data storage : Optical storage-recording materials
(300.6250) Spectroscopy : Spectroscopy, condensed matter
(300.6320) Spectroscopy : Spectroscopy, high-resolution
(300.6410) Spectroscopy : Spectroscopy, multiphoton
Zameer Hasan and Levent Biyikli, "Mechanism of high-density power-gated hole burning in Eu2+-doped sulfides," J. Opt. Soc. Am. B 18, 232-239 (2001)