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In Er(3+)/Yb(3+) codoped Na(2)O-ZnO-PbO-GeO(2)-TeO(2) (NZPGT) glass fiber, a clear and compact green upconversion amplified spontaneous emission (ASE) trace is observed, and the NZPGT glasses are proved to be a desirable candidate in fabricating low-phonon energy fiber. Intense green upconversion luminescence of Er(3+), balanced green and red upconversion emissions of Ho(3+), and dominant three-photon blue upconversion fluorescence of Tm(3+) have been represented. By varying the excitation power of 974 nm wavelength laser diode, a series of green and white fluorescences have been achieved in Tm(3+)/Er(3+)/Yb(3+) and Tm(3+)/Ho(3+)/Yb(3+) triply doped glass systems, respectively. These results reveal that high-intensity blue, green, and white upconversion ASE fluorescences, which can be adopted for lighting in minimally invasive photodynamic therapy and minimally invasive surgery, are reasonable to be expected in rare-earth doped NZPGT glass fibers.

A highly sensitive and flexible, multichannel thermometer prepared by exploiting the emission behaviors of Er3+ in Y7O6F9:Er/Yb crystal-embedded polyacrylonitrile fibers is reported. This sensor could be operated at 303–433 K, and the maximum relative sensitivity based thermal-coupling level was 1.285% K−1 at 303 K. More interesting is that the self-calibration could be achieved from the single Er3+ emission avoiding the intervention of other calibration tools. Repeatability experiments also confirmed the accuracy and durability of this fabricated material. Further details have been provided to reveal the multi-channel sensing mechanism, in which the green–green emission and red–red emission based thermal-coupling level, and the blue-green emission based non-thermal coupling level are discussed. All the above results showed that the Y7O6F9:Er/Yb crystal-embedded polyacrylonitrile fibers have extraordinary potential in intelligent wearable devices, industrial safety protection, and anti-counterfeiting mark fields. [ABSTRACT FROM AUTHOR]

Sr2(La1−xErx)F7/polyacrylonitrile composite fibers with special pliability and excellent crystal dispersibility have been fabricated, which provide smaller size and appropriate temperature sensitivity. Up-conversion emission shows quadratic dependence of the photoluminescence intensity on pump power, confirming the participation of two photons during the excitation processes. The composite fibers, combining main and auxiliary sensing derived from green and red emissions, give fibers the ability to obtain accurate results and better reproducibility. Among them, assigning the green emission as the main indicator of non-contact temperature sensing, the absolute and relative sensitivities are 0.514% K−1 and 0.654% K−1 at 373 K, respectively. Furthermore, the ratio of green and red emission serves as an auxiliary monitoring parameter to calibrate the deviation, where the absolute and relative sensitivities reach 7.208% K−1 and 0.901% K−1 at 373 K. In general, composite fibers with excellent dual-ratiometric temperature sensing are expected to be applied in biological probes, miniature devices and accurate temperature sensors. [ABSTRACT FROM AUTHOR]

Standard thermal diffusion of Er3+ into X-cut congruent LiNbO3 crystal with the MgO doping level close to the antiphotorefractive threshold concentration, 4.5 mol%, was attempted at the temperature close to Curie point of the crystal. Single-crystal x-ray diffraction, photoluminescence spectroscopy and secondary ion mass spectrometry (SIMS) were used to study the crystalline phase with respect to Er3+ ions and the depth profile of the diffused Er3+ ions. The results show that the thickness of the Er metal film coating should not be thicker than 4.6 nm. In this case, the diffusion is complete, the diffused surface is clean, and the Er3+ ions in the diffused layer still retain the LiNbO3 phase. On the other hand, the diffusion will be incomplete if the initial thickness of the Er metal film is thicker than 4.6 nm. The residual Er3+ ions form ErNbO4 grains on the surface of the crystal. SIMS analysis shows that the diffused Er3+ ions follow a monoexponential decay profile. The experimental results also show that the diffusivity of Er3+ in the X-cut congruent Mg(4.5 mol %):LiNbO3 is similar to 4.69×10-3 μm2/h at 1130 °C. Further vapor transport equilibration treatment following the standard diffusion procedure results in transformation of the diffused Er3+ ions from LiNbO3 into the ErNbO4 phase and, hence, substantial spectral change of the 1.5 μm emission. [ABSTRACT FROM AUTHOR]

(The origin of the formation of nanoprecipitates of ErNbO[SUB4] induced by vapor transport equilibration (VTE) in Er:LiNbO[SUB3] crystals was investigated by comparing x-ray powder diffraction patterns of VTE-treated, annealed and as-grown Er:LiNbO[SUB3] crystals. The results indicated that annealing an Er:LiNbO[SUB3] crystal in ambient atmosphere, whether the crystal is x or z cut, and whether it is highly or lower doped, does not influence its crystalline structure, and hence cannot cause the formation of the precipitate. The elevated temperature is not a sufficient requirement for the formation of this additional phase, but is only an essential prerequisite, together with the high-doping level of erbium. The incorporation of a certain amount of additional Li[SUP+] ions accompanying the VTE procedure is considered as the direct reason for the formation of the precipitate. The mechanism of the formation of the precipitates of ErNbO[SUB4] was tentatively suggested from both microscopic and macroscopic points of view. In addition, the origin of VTE-induced cracking, which occurs only in higher-doped x-cut crystals, was also considered based on the experimental results of annealed crystals. The incorporation of a certain amount of additional Li[SUP+] ions by the VTE procedure is again correlated with the cracking. [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]

Multiwavelength oscillation has been obtained in an erbium-doped fiber laser. A double-pass optical fiber Mach–Zehnder interferometer is employed as a comb filter inside the laser cavity. To reduce the homogeneous linewidth, the erbium-doped optical fiber was immersed in liquid nitrogen. Simultaneous oscillation of ten wavelengths is observed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 270–272, 1999. [ABSTRACT FROM AUTHOR]

Frequency upconversion of Er[sup 3+] in alkali bismuth gallate glasses have been investigated. The upconversion mechanisms are discussed, and the dominant mechanisms are excited state absorption for the [sup 2]H[sub 11/2]→[sup 4]I[sub 15/2] and [sup 4]S[sub 3/2]→[sup 4]I[sub 15/2] transitions, and energy transfer upconversion for the [sup 4]F[sub 9/2]→[sup 4]I[sub 15/2] transition. Intense green (around 525-550 nm) and red (around 660 nm) emission bands were observed under 800 nm excitation. At a pump intensity of 15.6 W/cm2, frequency upconversion efficiencies of 2.1x10[sup -2] and 4.8x10[sup -3] were obtained for the green and red emissions, respectively. The results are the highest among doped oxide glasses, and are comparable to those reported for Er[sup 3+]/Yb[sup 3+] codoped fluoride glasses. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]