Effect Of Er3 Research Articles

Luminescence of (Y1–x Er x )2O2S solid solutions under UV excitation

We have studied the effect of Er3+ concentration on the visible and IR luminescence of (Y1–xErx)2O2S solid solutions in the range 450–1600 nm under excitation at a wavelength of 365 nm.

Preparation of Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites and their visible-light photocatalytic activity in degradation of some organic dyes

In this paper, an up-conversion luminescence agent (Er3+:YAlO3), which can effectively transform the visible light in solar light into ultraviolet light, was prepared. Then, for a visible-light photocatalytic degradation reaction, the prepared Er3+:YAlO3 was coated by Co- and Fe-doped TiO2–ZnO films thorough sol–gel process, respectively, and the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were obtained. The crystal forms, particle sizes, chemical compositions, and weight change process of the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were analyzed by using XRD, TEM, SEM, EDX, and TG–DTA instruments. The photocatalytic activities of the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were evaluated through the degradation of azo fuchsine under visible light irradiation. It indicated that the visible light photocatalytic reduction ratio of Fe- and Co-doped TiO2–ZnO composites were 47.8 and 67.9 %, while after adding 15 wt% Er3+:YAlO3, the reduction ratio reached 93.5 and 95.5 %, respectively. In addition, the photocatalytic effect of Er3+:YAlO3/Co-doped TiO2–ZnO is better than that of Er3+:YAlO3/Fe-doped TiO2–ZnO.

Cataluminescence gas sensor for ketones based on nanosized NaYF4:Er

A novel gas sensor toward ketones based on cataluminescence generated on the surface of nanosized NaYF4:Er was developed. The sensing materials NaYF4:Er was synthesized by a simple hydrothermal method and characterized by powder X-ray diffraction, scanning electron microscope and energy dispersive X-ray spectroscopy. The effect of Er3+ doping concentration and crystallinity of NaYF4:Er on the CTL intensity were studied. When the Er3+ doping concentration reaches 20%, the materials show excellent sensing characteristics for ketones. Under the optimal experimental conditions, as represented by the acetone and butanone, the gas sensor has fast responses (3 s) and relatively low work temperature (250°C). The linear range of cataluminescence intensity versus concentration were 2.388–143.28μgmL−1 for acetone and 2.45–49.0μgmL−1 for butanone, with a detection limit (signal-to-noise ratio is 3) of 1.7μgmL−1 and 0.7μgmL−1, respectively. Foreign 11 substances in common have little interference which indicates the high selectivity of the CTL sensor for ketones.

NIR fluorescence spectroscopic investigations of Er3+-ions doped borate based tellurium calcium zinc niobium oxide glasses

A series of Er3+ ions doped tellurium calcium zinc niobium borate glasses were prepared by the melt quenching technique. The prepared samples were investigated by optical absorption and near infrared fluorescence spectroscopic studies. The obtained Judd–Ofelt intensity parameters Ωλ (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from absorption spectra and their results are studied and compared with reported literature. The stark-level energies of 4I13/2 excited and 4I15/2 ground states were evaluated by using both the absorption and emission measurements. The effect of Er3+ ion concentration on the emission intensity of 4I13/2→4I15/2 transition was discussed. Intense and broad 1.53µm infrared fluorescence is observed at 980nm diode laser excitation. Photoluminescence (PL) and its decay behavior studies were carried out for the transition 4I13/2→4I15/2 at 1.53µm emission. The broad emission together with higher values of the bandwidth (81nm), stimulated emission cross-section (32.25×10−22cm2) and lifetime (530µs for 1.0mol% of Er3+) of level 4I13/2 make these glasses attractive for broadband amplifiers. From the analysis of spectroscopic data, the present glass is a prospective photonic material for practical applications in the visible and NIR region.

Impact of incoherent pumping field and Er3+ ion concentration on group velocity and index of refraction in an Er3+-doped YAG crystal

The effect of Er3+ ion concentration and incoherent pumping field on the refractive index and group index in an Er3+: YAG crystal is investigated. It is shown that under different concentrations of Er3+ ion in the crystal, the index of refraction and absorption can be changed and a high index of refraction is accompanied by amplification in the medium. Also, it is shown that with the switching from subluminal to superluminal, or vice versa, light propagation can be obtained by different concentrations of Er3+ ions in the crystal.

Er3+ ion concentration effect on transient and steady-state behavior in Er3+:YAG crystal

The effect of Er3+ ion concentration on transient and steady-state behavior in 45-nm Er3+:YAG crystal is investigated. It is shown that by changing the signal field, the coherent field and the concentration of Er3+ ions in the crystal, the absorption, dispersion, and group index of the weak probe field can be adjusted. Also, it is found that the probe absorption occurs in the presence of population inversion and probe amplification is obtained in the absence of population inversion.

Role of Er3+ ion concentration and incoherent pumping field on optical bistability in Er3+:YAG crystal

In this paper, two atomic models are proposed in an 35 nm Er3+-doped YAG crystal. The effect of Er3+ ion concentration and incoherent pumping field on optical bistability is discussed. The results for two models show that the threshold of optical bistability for some Er3+ concentration reduces and for some concentration increases. We display that the incoherent pumping field makes the behavior of optical bistability for two proposed model completely different at identical conditions for Er3+ concentration. Our results show that in the absence and presence of incoherent pumping field some Er3+ concentration can lead to maximum and minimum OB threshold. We hope that our proposed model can be suitable for optimizing and controlling the optical bistability in Er3+:YAG crystal.

Comparison of optical properties between ladder and lambda-type EIT medium with Er3+ ion concentration in Er3+:YAG crystal

The effect of Er3+ doped ion concentration on optical properties of two type three-level schemes in 35 nm Er3+:YAG (yttrium aluminum garnet) crystal is studied. It is found that intensity threshold of optical bistability and multistability can be changed by Er3+ doped ion concentration. Moreover, switching from optical multistability to optical bistability can be done differently by Er3+ concentration in two types of three-level schemes. The steady-state and transient behaviors of absorption, dispersion and group index of weak probe field in two schemes are also discussed. In this study, we will report an initial study on optical properties in Er3+:YAG crystal and propose a basis for selecting the suitable concentration to carry out experimental investigations in the future.

Effects of Er3+:Ag codoping on structural and spectroscopic properties of lead tellurite glass ceramics

Structural, spectroscopic and optical properties of lead tellurite glass ceramics doped with variable amounts of erbium ions and codoped with fixed amounts of silver (Ag2O or Ag metallic nanoparticles, AgNPs) have been studied. The investigation of the samples was performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), diffuse reflectance ultraviolet–visible (DR-UV–vis) and photoluminescence (PL) spectroscopies. The average unit-cell parameter, crystallite size and the quantitative ratio of the crystallographic phases in the samples were evaluated from the XRD data. FTIR spectroscopy data show that the glass ceramics network mainly consists of TeO3 and TeO4 structural units. The increase of the Er2O3 content determines a TeO3→TeO4 conversion but the process is also influenced by the nature of the codopant (Ag2O or AgNPs) present in the samples. The optical band gap (Egopt) values, determined from the DR-UV–vis spectra, decrease with increasing the erbium content of the samples. Photoluminescence spectroscopy measurements evidenced the important peaks located at around 430nm and 708nm due to the Pb2+ ions and at 525 and 547nm due to the Er3+ ions present in the studied samples. The Er3+:Ag codoping was found to produce antagonistic effects (quenching/enhancement) of the luminescence emission of Er3+ ions in the studied samples.

Up-conversion fluorescence characteristics and mechanism of Er3+-doped TiO2 thin films

Er3+-doped TiO2 thin films were prepared by RF magnetron sputtering. The effects of Er3+ concentration and annealing conditions upon up-conversion fluorescence were studied. The result shows that 490 nm green emission and 670 nm red emission can be obtained from Er3+-doped TiO2 thin films excited by 980 nm lasers. TiO2 thin films with 1.0 mol% Er3+ manifested the best up-conversion property when the annealing temperature reached 900 °C. Under such conditions, we observed intense 490 nm green emission that has not been observed in powder or sol–gel samples and the mechanism of up-conversion fluorescence were studied. We also confirmed the up-conversion properties are closely related to the formation of Er2Ti2O7 in thin films, which is proved to reduce state densities of phonons and therefore inhibit nonradiative transition in an up-conversion process.

The relative intensity noise and relaxation oscillation characteristics of a distributed-feedback fiber laser

The relative intensity noise (RIN) and relaxation oscillation characteristics of distributed-feedback fiber lasers (DFB-FLs) have been investigated theoretically and experimentally. The effects of Er3+ doping concentration and phase-shift grating parameters such as the coupling coefficient on the RIN and relaxation oscillation characteristics of DFB-FLs are presented by an analytical model. Also, four DFB-FLs with dissimilar coupling coefficients are fabricated and tested to confirm the theoretical results. In addition, the influence of the external environment and the contribution of the pump power fluctuations are analyzed in detail by experiments.

Optical characterization of Er3+-doped zinc fluorophosphate glasses for optical temperature sensors

Trivalent erbium doped zinc fluorophosphate glasses have been synthesized and their luminescence properties in the green visible range have been investigated as a function of temperature. The Judd–Ofelt theory has been used to predict the transition probabilities, branching ratios and lifetimes for the various excited states of Er3+ ions in 0.5mol% of Er2O3-doped glass. The effect of Er3+ concentration on temperature dependent luminescence has been studied for the wide temperature range from room temperature up to 773K. The fluorescence intensity ratio of the green emissions associated to the two transitions from the thermally coupled 2H11/2 and 4S3/2 levels to the 4I15/2 level of Er3+ ion has been studied as a function of temperature, and in turn used to determine the thermal sensitivity and relative thermal sensitivity of the glasses. In the present study, the maximum value for the thermal sensitivity of 79×10−4K−1 at 630K has been obtained for the lowest (0.01mol%) concentration of Er2O3-doped glass, one of the highest sensitivity found in the literature and quite close to the theoretical sensitivity calculated from the Judd–Ofelt theory. The results reveal that the zinc fluorophosphate glass having relatively low concentration of Er3+ ions can be useful as an optical temperature sensor due to their high sensitivity and the absence of radiative energy transfer processes.

Effect of Er3+ doping on the thermal stability of TiO2 nanoparticulate xerogels

The effect of Er3+ doping on the thermal stability of TiO2 nanoparticulate xerogels prepared by a colloidal sol–gel route was investigated. It was found that the as-synthesized xerogels crystallize as anatase phase with crystallite sizes in the low nanoscale range ( 100 ± 5 m2/g). Nevertheless, it was also found that the Er3+ cations are deposited on the surface of TiO2 nanocrystallites thus resulting in xerogels with smaller and more uniform nanoaggregates. Most importantly, detailed analyses using X-ray thermo-diffractometry together with selective analyses by transmission electron microscopy, selected area electron diffractometry, and X-ray energy-dispersive spectrometry showed that the thermal stability of these TiO2 nanoparticulate xerogels increases with increasing Er3+ doping. Specifically, the nanocrystallite growth is slowed down, the onset temperature of the anatase-to-rutile phase transformation is delayed, and the anatase phase is retained up to greater temperatures as the Er3+ content increases, which are all phenomena attributable to the formation at low temperatures (i.e. ~200 °C) of solid solutions with Er3+ solutes within the TiO2 host. Moreover, these solid solutions also have lower thermal expansion coefficient than the undoped crystal structure. Finally, Er3+ doping increasingly promotes the precipitation at high temperatures of Er2Ti2O7 from the rutile TiO2 solid solution, with the precipitation temperature decreasing with increasing Er3+ doping content.

Luminescence and gain characteristics of 1.53 µm broadband of Er3+ in lead telluroborate glasses

Different concentrations (0.1, 0.5, 1.0 and 2.0mol%) of Er3+-doped lead telluroborate glasses were prepared by conventional melt quenching method. Up on 514.5nm laser excitation, the near infrared luminescence due to the 4I13/2→4I15/2 transition was analyzed. The absorption and emission spectra were used to determine the different spectroscopic parameters by means of the Judd–Ofelt and the McCumber theories. The obtained Judd–Ofelt intensity parameters were used to obtain the radiative transition probability, fluorescence branching ratio and radiative lifetime of the 4I13/2 emission state. The effect of Er3+ concentration on the emission intensity of 4I13/2→4I15/2 transition was discussed. The Stark-level energies of 4I13/2 excited and 4I15/2 ground states were evaluated using both the absorption and emission measurements. The wavelength dependent gain coefficient, G(λ) of 4I13/2→4I15/2 transition of Er3+ ion was determined using the absorption and emission cross-sections. The suitability of this glass as a host for Er3+-doped broad-band amplifiers and its advantage over other glasses were discussed.

The effect of Er3+ doping on the structure and thermoelectric properties of CdO ceramics

Abstract The effect of Er 3+ doping on the structure and thermoelectric transport properties of CdO ceramics was investigated. The solubility limit of Er 3+ in CdO was very small and that additions of more than about 0.5 at% Er 3+ resulted in the presence of Er 2 O 3 . With the addition of Er 3+ , the average grain size of Cd 1− x Er x O (0 ≤ x ≤ 0.015) decreased and the carrier concentration as well as mobility increased at room temperature. A small amount of Er 3+ doping resulted in a marked increase of electric conductivity and a moderate decrease of Seebeck coefficient. Although Er 3+ doping also leaded to an increase in thermal conductivity, a large ZT of 0.2 was achieved in x = 0.005 sample at 723 K due to the obvious improvement of power factor. The results demonstrate that CdO:Er is a new promising n-type thermoelectric material.

Effect of Er3+ Concentration on Upconversion in Hexagonal-Phase NaYF4:Er3+ Nanocrystals

A facile synthesis method was developed to produce hexagonal-phase of NaYF4 nanocrystals (NCs) doped with Er3+ in different concentration, which showed upconversion (UC) emission from infrared to visible spectral region. This proposed method is simple and less toxic compared with generally used method so far. It was found that up-conversion emission spectra of NaYF4:Er3+ NCs, excited at 1550 nm, included four peaks at about 980 nm, 800 nm, 660 nm and 540 nm. The effect of Er3+ concentration on UC in β-phase NaYF4:Er3+ NCs were discussed based on the excitation power dependence. The optimum Er3+ concentration for 2-step and 3-step UC was found to be around 10~30%.

Effects of Er3+ concentration on thermal sensitivity in optical temperature fluorotellurite glass sensors

Abstract The effects of Er 3+ concentration on temperature-dependent luminescence in fluorotellurite glass were studied in the 100–573 K range for its application as an optical temperature sensor. The temperature-induced changes in the Er 3+ green emissions associated to the transitions from the 2 H 11/2 and 4 S 3/2 thermalized levels to the 4 I 15/2 ground state were calibrated by doping the fluorotellurite glasses with three concentrations (0.01, 0.1 and 2.5 mol% of Er 3+ ions) and using commercial cw 488 nm laser excitation. The intensities, quantum efficiencies, line profiles and fluorescence intensity ratio of these thermalized green emitting levels are highly dependent on the optically active Er 3+ concentration and the position of the glass excited by the laser beam due to the existence of radiative and non-radiative energy transfer processes between Er 3+ ions. The maximum value for thermal sensitivity were obtained for the fluorotellurite glass doped with the lowest concentration of Er 3+ ions, 79 × 10 −4 K −1 at 541 K, one of the highest values found in the literature, and quite close to the theoretical thermal sensitivity calculated using the Judd–Ofelt theory. This study concludes that the calibration of optical temperature sensors based on Er 3+ ions is strongly affected by radiative energy transfer processes, therefore a relatively low concentration of Er 3+ ions should be used to avoid them.

Energy transfer and frequency upconversion in Er3+-Yb3+ codoped oxy-fluoro-tungstosilicate glasses

Er3+-Yb3+ codoped oxy-fluoro-tungstosilicate glasses with infrared-to-visible frequency upconversion luminescence were prepared by melting quenching in air. The effects of Er3+ doping on the optical properties of the samples were measured by means of techniques such as optical absorption spectra and photoluminescence spectra. The results showed that intense green and red signals centered at 546 and 665 nm, corresponding to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ by a multiphoton stepwise phonon-assisted excited-state absorption process, respectively, were simultaneously observed by exciting the samples with a diode laser operating at 980 nm at room temperature. The upconversion process was found very sensitive to Er3+ content at a constant Yb2O3 content of 5 mol.%. With the increase of Er3+ content from 0.5% to 1.5%, the upconversion intensity increased gradually. Further increasing of Er3+ content to 3.0% resulted in a significant fluorescence quenching. Moreover, the possible upconversion mechanisms were discussed based on the energy-matching conditions and the quadratic dependence on excitation power.

Effect of Er3+ concentration on the upconversion luminescence of GdOCl:Er3+ powders with excitation of 514.5 nm

GdOCl phosphors doped with different Er3+ concentration were prepared by modified solid state reaction. The structure and purity of the powders were analyzed by X-ray diffraction. Upconversion emissions from blue to violet to ultraviolet regions were observed with excitation of 514.5nm. Power-dependence analysis demonstrated that the two-photon upconversion process populated the luminescent levels 4G11/2, 2P3/2, 2H9/2, and 4F3/2, 5/2. The energy distribution of upconversion spectra depends on doping concentration, and the intensity ratio between involved energy levels changed with increasing Er3+ concentration. The dependence of spectral distribution on concentration was possibly ascribed to cross relaxation process of 2P3/2+4I15/2→4I13/2+2H9/2. Besides the cross concentration, excited state absorption and energy transfer upconversion were proposed to be the possible mechanisms for upconversion.

Spectroscopic properties in Er3+/Yb3+ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3+/Yb3+ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3+ and Yb3+ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd—Ofelt theory, the oscillator strength was computed. The lifetime of 4I13/2 level (τm) of Er3+ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3+ was calculated by the McCumber theory. The spectroscopic properties of Er3+ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.