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Optical and magneto-optical properties of Bi4Ge3O12 doped with aluminium and manganese

P. PETKOVA1,* , V. MARINOVA2, M. VELEVA3, T. DIMOV1, I. ILIEV1

Affiliation

  1. Shumen University "K. Preslavski", 115 Universitetska street, 9712 Shumen, Bulgaria
  2. Central Laboratory of Optical Storage and Processing of Information, Bulgarian Academy of Sciences, P.O. Box 95, 1113 Sofia, Bulgaria
  3. Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria

Abstract

The magneto-optical effect and photochromism in Mn+Al co-doped Bi4Ge3O12 single crystals are investigated in a wide spectral range. It is found that the photosensitivity of doped crystals is significantly shifted to the visible wavelengths. The Verdet constant is determined in two different states of the samples: the coloured state, obtained by exposure with ultraviolet (UV) light and the state developed after annealing at 400 oC. The spectra of the rotation angle are described by a sigmoidal function in the absorption range and by a quadratic function in the transmittance region. All doped crystals exhibite a strong photochromic effect at room temperature: this being fully reversible after thermal annealing or illumination with visible light. Annealing and UV exposure are used to modify the defect structure in the crystal lattice and thus influence the corresponding absorption bands..

Keywords

Verdet constant, doped Bi4Ge3O12 crystals, Photochromic effect, Magneto-optical effect.

Submitted at: Nov. 28, 2006
Accepted at: Feb. 15, 2007

Citation

P. PETKOVA, V. MARINOVA, M. VELEVA, T. DIMOV, I. ILIEV, Optical and magneto-optical properties of Bi4Ge3O12 doped with aluminium and manganese, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 2, pp. 278-281 (2007)