Luminescence of Er3+ in Oxyfluoride Transparent Glass-Ceramics
来源期刊：JOURNAL OF RARE EARTHS2006年第6期
论文作者：Steven H Morgan Akira Ueda Zhengda Pan Richard Mu
Key words：luminescence; transparent glass-ceramics; rare earths;
Abstract: Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics (TGCs) were obtained with the formation of β-PbF2∶Er3+ nanocrystals in the glass matrix were confirmed by X-ray diffraction. Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum (FWHM) of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er3+ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is red-shifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum (BWHM) of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier (EDFA). Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion luminescence was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of 4S3/2→4I15/2 transition and a weaker red emission centered at 662 nm because of 4F9/2→4I15/2 transition, generally seen from the Er3+ doped glasses, two violet emissions centered at 410 nm because of 2H9/2→4I15/2 transition and centered at 379 nm because of 4G11/2→4I15/2 transition were also observed from the TGC. The increased luminescence was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er3+ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er3+ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust, easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.
Steven H Morgan1，Akira Ueda1，Zhengda Pan1，Richard Mu1
(1.Department of Physics, Fisk University, Nashville, TN 37208, USA)
Abstract:Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics (TGCs) were obtained with the formation of β-PbF2∶Er3+ nanocrystals in the glass matrix were confirmed by X-ray diffraction. Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum (FWHM) of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er3+ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is red-shifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum (BWHM) of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier (EDFA). Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion luminescence was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of 4S3/2→4I15/2 transition and a weaker red emission centered at 662 nm because of 4F9/2→4I15/2 transition, generally seen from the Er3+ doped glasses, two violet emissions centered at 410 nm because of 2H9/2→4I15/2 transition and centered at 379 nm because of 4G11/2→4I15/2 transition were also observed from the TGC. The increased luminescence was attributed to the decreased effective phonon energy and the increased energy transfer between the excited ions when Er3+ ions were incorporated into the precipitated β-PbF2 nanocrystals. The results indicated two attractive spectroscopic properties of the Er3+ doped TGC samples, compared to glass samples, namely a reduced multiphonon decay rate and a reduced inhomogeneous broadening. In addition, these oxyfluoride TGC materials were robust, easy and flexibile to process, and possible to be fabricated in the fiber form for device applications.
Key words:luminescence; transparent glass-ceramics; rare earths;
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