Spectroscopic properties of Er3+- and Yb3+-doped soda-lime silicate and aluminosilicate glasses

Article

关键词: EXCITED-STATE ABSORPTION;    VISIBLE UP-CONVERSION;    WAVE-GUIDE AMPLIFIER;    ENERGY-TRANSFER;    ERBIUM;    IONS;    AMPLIFICATION;    TRANSITIONS;    PARAMETERS;    DYNAMICS;   

DOI  :  10.1103/PhysRevB.56.9302

来源: SCIE

【 摘 要 】

A spectroscopic investigation of an extensive series of Er3+-doped and Er3+, Yb3+-codoped soda-lime-silicate (SL) and aluminosilicate (AS) glasses is presented. Compared to SL glasses, 4f transitions in AS glasses show higher oscillator strengths, larger inhomogeneous broadening, and smaller crystal-field splittings of the respective excited-state multiplets. The Er3+ excited-state relaxation dynamics is adequately described by a combination of the Judd-Ofelt model and the energy-gap law. With the exception of I-4(13/2), multiphonon relaxation is dominant for all excited states, making it possible to efficiently pump the 1.55 mu m I-4(13/2) --> I-4(15/2) emission by excitation of I-4(11/2) at around 980 nm. The absolute I-4(13/2) luminescence quantum yield, for low 980-nm excitation density (similar to 5 W/cm(2)), eta, is similar to 0.9 at 0.4 mol % Er2O3 and drops to about 0.65 upon increasing Er2O3 to 1.2 mol %, indicating the onset of energy-transfer processes. Samples with high OH- impurity concentration suffer from significantly higher quenching of I-4(13/2) luminescence at higher Er3+ concentrations. Energy migration to the minority of Er3+ ions coordinated to OH-, followed by efficient multiphonon relaxation accounts for this effect. At low excitation densities, the strong near-infrared absorption of Yb3+ in combination with efficient Yb --> Er energy transfer increases the I-4(13/2) population density in Yb3+, Er3+-codoped samples by up to 2 orders of magnitude compared to equivalent samples without Yb3+. The dependence of eta on Yb3+ codotation of 0.4 mol % Er2O3-doped samples predicts that a minimum of similar to 0.8 mol % Yb2O3 is required to achieve efficient sensitization of Er3+ by Yb3+. The relative intensities of upconversion luminescence from S-4(3/2) and H-2(11/2) are used to analyze internal sample heating in detail. Due to the high absorption cross section of Yb3+, increasing the Yb3+ concentration in Yb3+, Er3+-codoped samples of given length increases the absorbed power and subsequently the total density of multiphonon emission, leading to internal temperatures of up to 572 K in 0.4 mol % Er2O3 samples codoped with 4 mol % Yb2O3 and excited with 51 kW/cm(2). Multiphonon relaxation from I-4(13/2) is shown to be inefficient even at these high internal sample temperatures. From upconversion luminescence spectra of a series of glasses, the thermal conductivity is estimated to be between 3.5 x 10(-2) and 7.7 x 10(-2) W m(-1) K-1, in good agreement with the known value of 4.8 x 10(-2) W m(-1) K-1 for soda-lime-silicate glass.

【 授权许可】

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