ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of Dy2S3-doped As12Ge33Se55 glasses demonstrate that the broad, below-gap PLE mechanism observed previously for rare-earth emissions in Er- and Pr-doped chalcogenide glasses is a general or universal feature of rare-earth-doped chalcogenide glasses, provided the transition energies of the rare earths are in the correct energy range. The PL spectrum excited in the 815 nm Dy3+ absorption band shows the 1150, 1340, and 1700 nm sequence of Dy3+ transitions expected for Dy-doped chalcogenide glasses. The PLE spectra of the 1340 (6F11/2,6H9/2→6H15/2) and 1700 nm (6H11/2→6H15/2) Dy3+ emissions exhibit broad excitation bands from ∼500 to 1000 nm, upon which the sharp intra F-band absorptions of Dy3+ are superimposed. These broad PLE bands are characterized by an exponentially decreasing slope with decreasing energy in the spectral range below the Urbach edge which is associated with the below-gap, defect- and impurity-induced exponential tails observed in the below-gap absorption spectra of chalcogenide glasses. At high energy, the exponentially rising Urbach absorption edge of the host glass, which leads to competing nonradiative decay mechanisms, eventually dominates the absorption spectrum and imposes an exponentially decreasing slope on the PLE spectra. These features of the broadband PLE have been observed in the PLE spectra of the Er-, Pr- and Dy-doped chalcogenide glasses we have studied. There is a difference in the relative strengths of the broad PLE bands, with the broadband for the 1340 nm PL band being a factor of 3 stronger than that for the 1700 nm PL emission. In addition, there is a shift in the peak energy of the different PLE spectra. Qualitatively speaking, the higher the energy of the luminescence transition, the higher the energy of the corresponding broad PLE peak. Proposed mechanisms for the broadband PLE of rare-earth emissions in chalcogenide glasses are discussed in the context of models for the below-gap, defect- and impurity-induced exponential absorption tails, including the possible role of lattice relaxation associated with charge transfer transitions and the involvement of transition metal impurities. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.363079
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