Optical properties of low-phonon-energy Ge30Ga5Se65:Dy2Se3 chalcogenide glasses

Homogeneous pure and dysprosium-doped (Ge30Ga5Se65)(100-x)(Dy2Se3)(x) glasses, x = 0, 0.01, 0.05, 0.1, 0.2, 0.3, 0.5, were synthesized. From the room temperature absorption spectra, the experimental oscillator strengths of six f-f electron transitions of Dy3+ ions and Judd-Ofelt intensity parameters were evaluated. The Dy3+ induced absorption bands were assigned to electron transition from the ground level H-6(15/2) to the H-6(13/2), H-6(11/2), H-6(9/2), F-6(11/2), F-6(9/2), H-6(7/2), F-6(7/2) and F-6(5/2), energy levels of Dy3+ ions. High values of the oscillator strengths and of the intensity parameter, Omega(2), originate apparently from the high covalence of chemical bonds in studied glasses. Using the Judd-Ofelt theory, the spontaneous emission probabilities, the branching ratios and the emission cross-sections were calculated. In the emission spectra of (Ge30Ca5Se65)(100-x)(Dy2Se3)(x) glasses, seven infrared luminescence bands (1150, 1140, 1560, 1760, 2170, 2470 and 2950 nm) were observed when pumped by 808 nm light. Using 905 nm excitation light, five emission bands at 1150, 1340, 1760, 2470 and 2950 nm were found. Only three luminescence bands were identified (1760, 2470 and 2950 nm) when excited by 1300 nm light. The bands were assigned to the individual electron transitions. The long-wavelength absorption edge (similar to 700 cm(-1)) corresponds to multiphonon Ge-Se bonds vibrations. (C) 2000 Elsevier Science Ltd. All rights reserved.