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The thermal diffusion of Er3+ into X- and Z-cut congruent LiNbO3 crystal in Li-enriched atmosphere [i.e., vapor transport equilibration (VTE)], created by Li3NbO4–LiNbO3 two-phase powder at the temperature around 1130 °C, was attempted. Single-crystal x-ray diffraction, micro-Raman, photoluminescence spectroscopy, and secondary ion mass spectrometry (SIMS) were used to study the crystalline phase with respect to Er3+ ion and the Er3+ diffusivity. The results show that the thickness of the Er film coated should not be thicker than 10 nm for an X-cut plate and 15 nm for a Z-cut plate. In this case, the diffusion is complete if the duration is long enough (>150 h) and the Er3+ ions in the diffused layer still retain the LiNbO3 phase. On the other hand, if the initial thickness of the Er metal film is thicker than 10 nm for the X-cut plate and 15 nm for the Z-cut plate, the diffusion will be incomplete no matter how long the duration is. This is because the residual Er3+ ions form irremovable ErNbO4 grains on the surface of the crystal. SIMS analysis on an X-cut VTE (1130 °C/192 h) and a Z-cut VTE (1129 °C/158 h) crystal coated, respectively, with 10 and 15 nm thick Er film reveals that the Er diffusion shows obvious anisotropy with the mean diffusion coefficients of 0.0155 and 0.0957 μm2/h, respectively. The surface concentrations are 1.5×1020 and 1.0×1020 at./cm3, respectively. The diffused Er3+ ions follow the stretched-exponential decay profile with a stretching factor of 1.85 and 3.5, respectively. The Li/Nb ratio in the Er-diffused layer is similar to 99.4% for the X-cut sample coated with 10 nm thick Er film and 99.3% for the Z-cut crystal coated with 15 nm thick Er film. The rms roughness of the diffused surface is better than 6 and 4 nm for the X-cut and Z-cut samples, respectively. [ABSTRACT FROM AUTHOR]

Buried channel waveguide amplifiers in erbium/ybtterbium codoped phosphate glass were fabricated using proton-beam writing. Single-mode waveguides were fabricated with fluences ranging from 0.4 to 2.0×1015 particles/cm2. The end-of-range and surface profiles of the waveguides were investigated using atomic force microscopy. The waveguiding effect was investigated using the end-fire coupling technique. From the near-field mode profiles, the refractive index profiles of these waveguides were recovered using the propagation mode near-field method. From these results, it can be deduced that for phosphate glass waveguides fabricated with fluences <1.0×1015 particles/cm2, the ionization from the electronic stopping, rather than the nuclear damage processes, is the major contributing factor leading to an increase in the refractive index near the end of range. [ABSTRACT FROM AUTHOR]

At room temperature, polarized visible and near infrared emission characteristics of 488 nm pumped vapor transport equilibration (VTE) treated Er:LiNbO[sub 3] crystals were investigated in comparison with the corresponding as-grown ones. The observed characteristics of the VTE crystal, whether it precipitates or not, include the retained polarization dependence, slight shift (less than 5 Å) of peak position, narrowing of some individual emission peaks, the appearance of additional emission peak near 1536.5 nm and the about 10% lengthening of 1.5 µm lifetime. In addition, in the case of lower Er doping level, the spectral shape are well reserved for the VTE crystals and no obvious changes in both visible and IR emission intensity. On the other hand, for those highly doped crystals, the VTE treatment not only results in a definite change of relative intensity between some emission peaks in IR region, but also causes the drop of both visible and IR emission intensity. Combining with the related absorption characteristic allow to conclude that the drop of the emission intensity results from the scattering of the nanocrystalline grains inside these crystals formed by VTE treatment. [ABSTRACT FROM AUTHOR]

In this letter, we present the dc characteristics, stability, and low-frequency noise (LFN) measurements, for n-type indium arsenide nanowire (NW) parallel-array thin-film transistors (TFTs) with a global back gate. These devices perform with mobilities ranging from 200-1200 cm2V-1s-1 and produce a threshold voltage shift less than 0.25 V after 10 000 s of stress. The resulting LFN measurements indicate that the 1/f noise can be modeled by the number fluctuation model, at low drain currents, which can provide an essential guideline for the device design considerations of NW TFTs. [ABSTRACT FROM AUTHOR]

Sm3+ doped germanotellurite glasses (NZPGT) with maximum phonon energy of 793cm−1 have been prepared and characterized. Judd-Ofelt parameters Ωt (t=2, 4, 6) have been calculated to be 3.52×10−20, 4.70×10−20 and 1.90×10−20cm2, respectively. Large value of Ω2 indicates a high asymmetry and covalent environment around Sm3+ in the glass system. The maximum stimulated emission cross-section of the dominant transition 4G5/2→6H9/2 peaking at 645.0nm was derived to be 10.00×10−22cm2, predicting that the red fluorescence emission can be efficiently extracted from the optical glasses. The internal quantum efficiency and external quantum yield of 0.4wt% Sm2O3 doped NZPGT glasses were deduced to be 82.5% and 6.0%, respectively. The results demonstrate that Sm3+ doped NZPGT glasses are a potential candidate for developing tunable visible lasers, compact light sources and solid-state display devices. [ABSTRACT FROM AUTHOR]