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980-nm-upconverted 530 and 550 nm Er 3+ green fluorescence spectra of Er 3+ /Yb 3+ -codoped NaGd(WO 4 ) 2 submicron crystals were measured in the temperature range of 298-383 K. A sextuple ratiometric thermometry is proposed. It is established on the basis of six schemes of fluorescence intensity ratio (FIR) that considers three component peaks of the 530 nm emission band and two component peaks of the 550 nm emission band, which involve electronic transitions between two Stark sublevels of Er 3+ . The study shows that the phosphor shows strong green fluorescence, which is verified by measured quantum yield, and thermally stable spectral structure desired for the sextuple ratiometric thermometry. All of the six FIR schemes display highly efficient sensing performances with slightly different thermal sensitivities. Each scheme gives a temperature value and the six schemes give an averaged result. In parallel, we have also carried out an ex vivo experimental study on the temperature characteristics of the green fluorescence of the phosphor. Almost same results have been obtained, verifying biological applicability of the phosphor. The ex vivo experimental results also show that the sextuple thermometry increases considerably the accuracy and reliability of temperature measurement in comparison with the conventional intensity integration method., (Copyright © 2019 Elsevier B.V. All rights reserved.)

An erbium-doped Lu3Ga5O12(LuGG) single crystal was grown by the Czochralski method. The crystalline phase in the grown crystal was analyzed by powder X-ray diffraction. The erbium-ion emission spectra of the crystal were acquired. The erbium-ion emission cross-section (ECS) spectrum was computed from the acquired emission spectrum. The erbium-ion absorption cross-section (ACS) spectrum was computed using the McCumber relationship. The results are discussed in contrast to those computed from the acquired absorption spectrum, and the comparison shows that both methods give consistent results. The temporal characteristics of the emissions were also studied based on 0.98 μm pulse pumping. The study shows that the infrared emissions at 1.0, 1.5, and 2.8 μm show mono-exponentially temporal behavior. Instead, the decays of two visible emissions at 0.56 and 0.67 μm show considerable non-exponential features; each trace can be fitted double-exponentially. The non-exponential behavior is associated with those erbium ions that are present in the form of clusters, which enables non-radiative upconversion depopulation and hence additional contribution to the decay through cross relaxation between the erbium ions in clusters. The study also shows that about half of the erbium ions are present in the cluster state in the studied crystal. [ABSTRACT FROM AUTHOR]

Fluorescence and absorption spectra at 530 nm (2H11/2→4I15/2), 560 nm (4S3/2→4I15/2), 660 nm (4F9/2→4I15/2), 980 nm (4I11/2→4I15/2), 1530 nm (4I13/2→4I15/2), and 2710 nm (4I11/2→4I13/2) of Er3+ in Gd3Ga5O12 single‐crystal codoped with Pr3+ have been measured. Judd‐Ofelt analysis yields the intensity parameters Ω2 = (0.68 ± 0.03) × 10−20 cm2, Ω4 = (0.60 ± 0.07) × 10−20 cm2, and Ω6 = (0.90 ± 0.17) × 10−20 cm2. A comparison with previously reported values of Er3+‐only doping case shows that Pr3+‐codoping causes slight change of both Ω2 and Ω4, while onefold increase of Ω6. From calculated radiative rates and measured fluorescence spectra, Er3+ emission cross‐section spectra were calibrated at first. Then, the absorption cross‐section spectra were calculated using McCumber relation. In parallel, the absorption cross‐section spectra were also obtained from the measured absorption spectrum, and compared with those obtained from the McCumber relation. The comparison shows that both methods give consistent result of absorption cross‐section spectrum. Further comparison with Er3+‐only doping case shows that Pr3+‐codoping causes considerable change of Er3+ cross‐section value. In spectrally mixing regions of Er3+ and Pr3+, Pr3+ emission affects little the determination of Er3+ emission cross‐section as Pr3+ fluorescence is much weaker than Er3+ fluorescence due to low Pr3+ concentration. [ABSTRACT FROM AUTHOR]

A previous paper [D. K. Sardar et al., J. Appl. Phys. 93(5), 2602 (2003)] has reported Judd–Ofelt (J–O) spectroscopic properties of Er3+ in garnets Y3Al5O12, Y3(Sc2Ga3)O12, and Gd3Ga5O12. In that paper, the possible magnetic-dipole contribution to the oscillator strength, which is non-zero for the 4I13/2 ↔ 4I15/2 (1.5 μm) transition of Er3+, has been erroneously omitted in their J–O calculation, resulting in incorrect results of relevant spectroscopic parameters. In this Comment, we point out the error, perform correct J–O analysis, and report correct results. [ABSTRACT FROM AUTHOR]

Some Er 3+ -doped LiTaO 3 plates were prepared by in-diffusion of Er-metal film locally coated onto congruent Z -cut substrate in air at a wide temperature range from 1000 to 1500 °C. After diffusion, Er 3+ -doping effect on LiTaO 3 refractive index and Li 2 O out-diffusion arising from Er 3+ in-diffusion were studied at first. Refractive indices at the doped and undoped surface parts were measured by prism coupling technique and the surface composition was estimated. The results show that Er 3+ dopant has small contribution to the LiTaO 3 index. Li 2 O out-diffusion is slight (Li 2 O content loss <0.3 mol%) for the temperature below 1300 °C while is moderate (Li 2 O content loss <0.6 mol%) for the temperature above 1400 °C. The Er 3+ profile was studied by secondary ion mass spectrometry. The study shows that the diffused Er 3+ ions follow either a complementary error function or a Gaussian profile. Characteristic parameters including diffusivity, diffusion constant, activation energy, solubility, solubility constant and heat of solution were obtained and compared with the LiNbO 3 case. The comparison shows that the diffusivity and solubility in LiTaO 3 are considerably smaller than in LiNbO 3 because of the difference of Ta and Nb in atomic weight. [ABSTRACT FROM AUTHOR]

Abstract Under 980 nm wavelength excitation, 530 and 550 nm green upconversion emission spectra of erbium-doped gadolinium gallium garnet single-crystal were measured in the temperature range of 298–423 K for ratiometric thermometry based on fluorescence intensity ratio (FIR). The crystal shows strong emission intensity, highly efficient ratiometric thermometric performance, as well as thermally stable emission spectral structure, it is thus a promising luminescent material for ratiometric thermometry. A multiple ratiometric thermometry is proposed and demonstrated in comparison with the usually adopted ratiometric thermometry based on integrated emission intensity. The multiple ratiometric thermometry considers six FIRs involving two component peaks of the 530 nm emission band and three component peaks of the 550 nm emission band, which result from an electronic transition from one Stark sublevel of the 2H 11/2 or 4S 3/2 state to another of the ground state 4I 15/2 of Er3+. All the six FIR schemes show highly efficient sensing performances with slightly different temperature characteristics. The temperature is overall determined by the six FIR schemes, largely increasing the reliability of temperature measurement. Graphical abstract We have studied ratiometric thermometry based on six fluorescence intensity ratios (FIR) involving two component peaks of 530 nm emission band and three component peaks of 550 nm emission band of erbium-doped gadolinium gallium garnet single-crystal. All the six EIR schemes display higher, slightly different relative sensitivities and thermal resolutions. The temperature is overall and reliably determined by the six EIR schemes. In addition, the crystal shows strong green upconversion emissions and thermally stable spectral structure, it is thus a promising material for the ratiometric thermometry. The multiple ratiometric thermometry based on the material has highly efficient performance, and is thus promising for reliable temperature detection in electromagnetically and/or thermally harsh environments and some industrial processes. fx1 [ABSTRACT FROM AUTHOR]

We have developed a simple, low-cost and highly efficient optical temperature sensor based on intensity ratio of down-conversion green fluorescence of Er 3+ ions doped in SrGdGa 3 O 7 single crystal. The sensor consists simply of a 384 nm light emitting diode, two narrow-band interference filters, two Si-photocells and two multimeters, without use of a monochromator or spectrometer or focusing lens. It has a simple, compact structure and is low-cost. The experimental results show that the device displays highly efficient sensing performance with good signal-to-noise ratio and high thermal resolution and temperature sensitivity, which has a value of (5.5-102.1) × 10 −3 K −1 in the considered temperature range of 100–430 K. In addition, the experiments were repeated using a spectrometer and consistent results are obtained. [ABSTRACT FROM AUTHOR]

Judd-Ofelt (J-O) spectroscopic knowledge of a rare-earth-doped luminescent material is crucial to its application. Although a large number of papers with regard to the J-O study of various rare-earth-doped luminescent materials have been reported each year, few papers presented the errors of the J-O intensity parameters Ω i (i = 2, 4, 6) and radiative probabilities evaluated from them. Present study focuses on the error evaluation of the J-O parameters and radiative probabilities. An error theory is established for the J-O analysis and radiative probability. Two error analysis methods based on root mean square of the difference either between measured and calculated oscillator strengths (δf rms) or between measured and calculated line strengths (δS rms) are studied. Explicit error expressions are presented for the J-O parameters and radiative probability. The validity of the theory is verified by applying it to widely studied Er3+, Tm3+, Ho3+ and Nd3+ ions that are doped into four single-crystals (LiNbO 3 , SrGdGa 3 O 7 , LiYF 4 and YVO 4) and a glass. The two methods are identical in nature and give similar results of errors of Ω i. [ABSTRACT FROM AUTHOR]