Upconversion Emission Of Er3 Research Articles

Li+共掺杂对掺Er3+:TiO2粉末上转换发光特性的影响

Li+共掺杂对掺Er3+:TiO2粉末上转换发光特性的影响

Spectroscopic properties of new luminescent system based on vanadate(V) crystal doped with erbium ions

Er 3+-doped KCaY(VO 4) 2 microcrystalline samples were synthesized using a high temperature solid-state reaction technique. Spectroscopic properties of Er 3+: KCaY(VO 4) 2 are studied and the nature of emissions is discussed. A strong green and infrared luminescence were observed under excitation at 314 nm in the O 2−→V 5+ charge-transfer transitions and direct excitation of Er 3+ ions at 435 nm. A strong emission lines in the blue region are due to the transitions of VO 4 3− ions have been observed at 77 K. The Judd–Ofelt parametrization scheme has been applied to the analysis of the room temperature absorption spectra in order to evaluate the intensity parameters, the branching ratios and the radiative lifetimes of the 4I 13/2, 4I 11/2, 4F 9/2 and 4S 3/2 emitting levels. The effective cross-section has been calculated for the 4I 13/2→ 4I 15/2 transition, indicating that the title compounds is a promising active medium for application in the three-level laser system. The up-conversion emission in Er 3+: KCaY(VO 4) 2 was investigated at 300 K. The decay profiles of the Stokes and anti-Stokes emissions were measured and the mechanism of up-conversion luminescence is discussed.

Efficient UV–visible up-conversion emission in Er3+/Yb3+ co-doped La2O3 nano-crystalline phosphor

A nano-crystalline La2O3: Er3+/Yb3+ phosphor sample has been synthesized through the solution combustion route using urea as a reducing agent. Thermal, structural and optical characterizations have been carried out to explore several of its properties. By thermal analysis one concludes to the presence of moisture and hydroxide phases [La(OH)3 and LaOOH] of lanthanum in the as-synthesized sample, which further changes to La2O3 phase above 600°C temperature. Up-conversion (UC) study shows the intense emission bands in the UV, blue, green and red regions. This paper also reports the first observation of UC emission bands extending up to the UV (240 nm) region on excitation with 976 nm wavelength. Heat treatment of the samples shows a change in the crystallite phase along with crystallite growth and relative UC luminescence intensities. The input pump power dependence shows the involvement of up to four photons.

Up-conversion emissions of Er3+-Yb3+ codoped Al2O3 nanoparticles by the arc discharge synthesis method

The Er3+-Yb3+ codoped Al2O3 nanoparticles with an average particle size of about 50 nm have been synthesized by an arc discharge synthesis method. The green and red up-conversion emissions centered at about 526, 547 and 677 nm, corresponding respectively to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, were detected by a 978-nm semiconductor laser diode excitation. The Annealing has evident effect on the up-conversion emissions of the samples: The red up-conversion emission is noticeable before annealing; however, the green up-conversion emission becomes predominant after annealing. The mixture of (Er,Yb)3Al5O12 and α-(Al,Er,Yb)2O3 phases is more favorable for green up-conversion emissions due to an enhancement of the ESA (I) of 4I11/2+a photon→4F7/2 and ET (III) of 2F5/2(Yb3+)+4I11/2(Er3+)→2F7/2(Yb3+)+4F7/2(Er3+) processes. The two-photon absorption up-conversion process is involved in the green and red up-conversion emissions. The results have proved that arc discharge synthesis is a new promising preparation technology for optical materials.

Excitation processes of up-conversion green emission for Er3+ and Yb3+ codoped tellurite glass

This paper analyzed the build-up characteristics of Er3+ 4S3/2 and the relationships between Er3+ 4S3/2，4I11/2 and Yb3+ 2F5/2 according to the energy structure for green up-conversion emission and relative transition rating function model for Er3+-Yb3+ codoped tellurite glass. Through fitting the build-up and decay curves by the model the relative parameters for rating equation model were determined，and the relative value between energy transfer and excited state absorption when population of 4S3/2 energy tend to be stable was calculated，also the dynamic processes in green up-conversion emission of Er3+-Yb3+ codoped tellurite glass were analyzed.

A New Blue, Green and Red Upconversion Emission Nanophosphor: BaZrO3:Er,Yb

Strong Blue, green, and red upconversion emission of Er3+ in nanocrystalline BaZrO3:(Yb3+Er3+) is observed. Powder samples were obtained by a facile hydrothermal process at 100 degrees C. The as synthesized nanocrystallites preserve a stable cubic perovskite phase under subsequent annealing treatment up to 1000 degrees C. No other phase or segregation of other compounds was detected. Crystallites sizes were around 115 nm and well faceted. Under IR excitation in the range between 900 and 1050 nm the Er3+ blue emission was almost not present in single Er3+ doped BaZrO3, whereas it became easily observable when Yb3+ was added as codopant. Besides, both green and red upconversion emission or upconverted signal of Er3+ are enhanced by around three orders of magnitude in comparison with the single Er3+ doped BaZrO3. The strong blue emission presents dependence on both excitation power and excitation wavelength. This is the first time that upconversion emission is observed in BaZrO3. A possible mechanism for the upconversion process that leads to the observed blue, green and red emissions under NIR excitation is suggested based on the experimental results.

Upconversion emission in Er3+-doped lead niobium germanate thin-film glasses produced by pulsed laser deposition

Thin films of Er3+-doped lead–niobium germanate have been produced by pulsed laser deposition from Er3+-doped 25PbO2–25Nb2O5–50GeO2 (mol%) transparent glasses with an Er content in the range 0.5–3 wt%. The room-temperature infrared to visible upconversion properties of these thin films have been investigated under 800-nm laser excitation. An energy transfer upconversion mechanism has been identified to be responsible for the population of the 4S3/2:2H11/2 excited level, from which an intense green emission occurs. A rate equation analysis supports the proposed mechanism.

Spectroscopic characteristics of Er3+/Yb3+:LiLa(WO4)2 crystal

The spectroscopic characteristics of Er3+/Yb3+:LiLa(WO4)2 crystal were investigated. Based on the Judd–Ofelt theory, the following intensity parameters Ωλ were obtained: Ω2=9˙03 × 10–20 cm2, Ω4=2˙02 × 10–20 cm2 and Ω6=0˙59 × 10–20 cm2. The upconversion emission of Er3+/Yb3+:LiLa(WO4)2 crystal was investigated under excitation with the 976 nm diode laser. The Er3+/Yb3+:LiLa(WO4)2 crystal has the intensity parameters Ωλ and a strong emission of 562 nm wavelength. Er3+/Yb3+:LiLa(WO4)2 crystal may be regarded as an upconversion laser material for the green light.

Near-infrared to visible up-conversion emissions of Er3+ doped Al2O3 powders derived from the sol-gel method

The Er3+ doped Al2O3 powders were prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)3·5H2O]. The different phase structure, including three crystalline types of (Al,Er)2O3 phases, γ, θ, α, and two Er-Al-O phases, ErAlO3 and Al10Er6O24, was obtained with the 1 mol% Er3+ doped Al2O3 powders at the different sintering temperatures of 600–1200°C. The green and red up-conversion emissions centered at about 523, 545 and 660 nm, corresponding respectively to the 2H11/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+, were detected by a 978 nm semiconductor laser diodes excitation. The phase structure and OH content had evident influence on the up-conversion emissions intensity. The maximum intensities of both the green and red emissions were obtained respectively for the Er3+ doped Al2O3 powders sintered at 1200 °C, which was composed mainly of α-(Al,Er)2O3, less of ErAlO3 and Al10Er6O24 phases, and with the least OH content. The two-photon absorption up-conversion process was involved in the green and red up-conversion emissions of the Er3+ doped Al2O3 powders.

Enhanced 1.5μm emission and simultaneously suppressed green upconversion emission in Er:LiNbO3 crystals heavily codoped with MgO

Enhanced 1.5μm emission and simultaneously suppressed green upconversion emission was observed for Er(1.0mol%):LiNbO3 crystals codoped with 8mol% MgO. The heavy MgO codoping results in the lengthening of the 1.5μm emission by 11.7%. Time-resolved spectroscopy study shows that the decay trace of the green upconversion emission of the Er∕Mg codoped crystal is obviously nonexponential. These spectroscopic characteristics are associated with the lower concentration of the cluster sites of Er3+ ion, the higher nonradiative energy transfer upconversion probability, and the lower OH− content in the crystal.

Efficient green and red upconversion emissions inEr3+/Yb3+ co-doped ZnAl2O4 phosphor obtained by combustion reaction

Thin ceramic powders of zinc aluminateZnAl2O4 co-dopedwith Er3+ and Yb3+ were prepared by a combustion reaction and characterized from the spectroscopic point ofview, with the aim of investigating the effect and mechanisms of upconversion emissions.The characteristic cubic spinel structure was predominantly formed for all doped samples,and intense upconversion emission was observed in the green and red spectralregions, under 980 nm diode laser excitation. The upconversion mechanism of bothemissions was confirmed to involve two photon absorptions and it was foundthat the efficiencies of the emissions are considerably enhanced by increasing theYb3+ concentration inrelation to Er3+. The resultsindicate the potential of ZnAl2O4:Er3+,Yb3+ phosphor powders for applications in luminescent display panels and other photonicdevices.

Optical thermometry through infrared excited green upconversion emissions in Er3+–Yb3+ codoped Al2O3

Fluorescence intensity ratio (FIR) variation of green upconversion emissions at 523 and 545nm in the Er3+–Yb3+ codoped Al2O3 has been studied as a function of temperature using a 978nm semiconductor laser diode as an excitation source. In the temperature range of 295–973K, the maximum sensitivity and the temperature revolution derived from the FIR technique are approximately 0.0051K−1 and 0.3K, respectively. The Er3+–Yb3+ codoped Al2O3 material with the highest operating temperature up to 973K, the higher temperature revolution, and the fluorescence efficiency indicated that it is promising for applications in optical high temperature sensor.

Morphology-dependent upconversion luminescence of ZnO:Er 3+ nanocrystals

Morphology impact on the upconverted luminescence of ZnO:Er 3+ nanocrystals was studied with controllable morphology of nanorod, prickly sphere-like, column-like, branch rod, prism-like, and grain-like, prepared via the cetyltrimethylammonium bromide (CTAB)-assisted hydrothermal process. The upconversion emission of Er 3+ with 980 nm excitation demonstrated morphology sensitivity which was related with the local environments of Er 3+ ions in ZnO and doping efficiency. Under ultraviolet (UV) direct excitation, where exciton and defect emissions of ZnO appeared, morphology sensitivity was discussed in terms of surface-to-volume ratios.

Optical high temperature sensor based on green up-conversion emissions in Er 3+ doped Al 2O 3

Er 3+ doped Al 2O 3 has been prepared by a non-aqueous sol–gel method using aluminum isopropoxide as precursor, acetylacetone as chelating agent, nitric acid as catalyzer, and hydrated erbium nitrate as a dopant in an isopropanol environment. The fluorescence intensity ratio (FIR) of the green up-conversion emissions at the wavelengths of about 523 and 545 nm in the Er 3+ doped Al 2O 3 was studied as a function of temperature over a wide temperature range of 295–773 K, using a 978 nm semiconductor laser diode (LD) as an excitation source. The maximum sensitivity and the temperature resolution derived form the FIR of the green up-conversion emissions are approximately 0.0052 K −1 and 0.3 K, respectively. It is demonstrated that the prototype optical high temperature sensor based on the FIR technique from the green up-conversion emissions in the Er 3+ doped Al 2O 3 is promising for applications in high temperature measurement.

High Efficiency Infrared-to-Visible Upconversion Emission inEr3+,Yb3+, and Ho3+ Codoped Tellurite Glasses

A novel method of codoping the Er3+, Yb3+, and Ho3+ions in tellurite glasses is demonstrated to obtain a high efficiency ofinfrared-to-visible upconversion. Three intense emission bands observedin Er3+, Yb3+, and Ho3+ codoped tellurite glassescentred at 525, 547, and 657 nm correspond to Er3+: 2H11/2→4I15/2, Er3+: 4S3/2→4I15/2+Ho3+: 5S2(5F4)→5I8, andEr3+: 4S3/2→4I15/2+Ho3+: 5F5→5I8 transitions, respectively. No visible upconversion quenchingphenomenon is observed when three rare-earth ions are codoped togetherin tellurite glasses. In contrast, the upconversion intensity ofred and green emissions in Er3+, Yb3+, and Ho3+codoped glasses is enhanced largely when compared withEr3+/Yb3+-codoped glasses. The dependence of upconversionintensities on excitation power and the possible upconversionmechanisms are evaluated. The three emissions are based ontwo-photon absorption processes.

Microstructure and luminescence of transparent glass ceramic containing Er 3+:BaF 2 nano-crystals

Transparent BaF 2–SiO 2 glass ceramics doped with different content of Er 3+ were prepared by sol–gel method. The microstructural evolution of the samples was studied with X-ray diffraction (XRD), transmission electron microscope (TEM), absorption and infrared spectra (IR). BaF 2 nano-crystals with 2–15 nm in size, depending on the crystallization temperature, distributed homogeneously among the amorphous silica matrix. The BaF 2 lattice parameters decreased with the increasing of Er 3+ doping, indicating the incorporation of Er 3+ into nano-crystals, which was further confirmed by energy dispersive X-ray spectroscopy (EDS) and absorption spectra analysis. The upconversion emissions of Er 3+ emerged under the excitation at 980 nm for glass ceramic heat-treated at 800 °C.

Radiative and non radiative spectroscopic properties of Er3+ ion in tellurite glass

We have investigated in detail the mechanism of infrared emission and upconversion emission of Er3+ in tellurite glass as a function of the dopant concentration. Both the infrared and upconversion emissions are competing processes and the efficiency of infrared emission at 1534nm is 100% at the lowest Er content (0.5mol%) and reduces to 50% at higher dopant concentration (>2mol%). The green upconversion emission at 548nm is mainly due to the excited state absorption (ESA) from 4I11/2, which populate the 4F7/2 level. In addition to this, the possible energy transfer (ET) through Er3+(4I11/2)+Er3+(4I11/2)→Er3+(4F7/2)+Er3+(4I15/2) can also results in the green emission as is noticed from the concentration dependent efficiency change of the green emission. The fluorescence quenching of green emission with Er concentration may be related with the cross relaxation (CR) process 2H11/2+4I15/2→4I9/2+4I13/2. The red emission is due to the combined effect of the ESA from level 4I13/2 to 4F9/2, the energy transfer process described by Er3+(4I13/2)+Er3+(4I11/2)→Er3+(4F9/2)+Er3+(4I15/2) and the cross relaxation process.

Judd–Ofelt analysis and upconversion emission of Er3+–Yb3+ co-doped oxyfluoride glass ceramics containing LaF3 nanocrystals

Er3+–Yb3+ co-doped glasses and glass ceramics containing LaF3 nanocrystals were prepared and their absorption spectra obtained. The Judd–Ofelt parameters Ω t (t = 2, 4, 6) for f–f transition of Er3+, as well as spontaneous emission probabilities, branching ratios and radiative lifetimes for stimulated emission of each band were determined. Addition of Er3+ and Yb3+ ions into low-phonon energy LaF3 nanocrystals makes the upconversion emission of Er3+–Yb3+ co-doped glass ceramic much stronger than that of Er3+–Yb3+ co-doped glass.

Green and red upconversion luminescence in Er 3+-doped and Er 3+/Yb 3+-codoped SrTiO 3 ultrafine powders

Er 3+-doped and Er 3+/Yb 3+-codoped strontium titanate (SrTiO 3) ultrafine powders were prepared in a molten NaCl flux. The intense green and red emissions around 528 nm, 550 nm and 662 nm corresponding to the 2H 11/2 → 4I 15/2, 4S 3/2 → 4I 15/2 and 4F 9/2 → 4I 15/2 transitions, respectively, of Er 3+ ions were observed under excitation at 980 nm. A great enhancement of the visible upconversion emissions in Er 3+/Yb 3+-codoped sample was observed. Excited state absorption and energy transfer process are discussed as the possible mechanisms for these emissions.

Optical properties of Er3+ in TeO2-based oxyhalide glasses pumped by 977nm

We report on fluorescence and upconversion emissions of Er3+-doped TeO2-ZnO-PbCl2 tellurite-based oxyhalide glasses under 977nm laser diode excitation. A strong 153μm emission from 4I13/2→4I15/2 transition with a full width at half maximum of ～69 nm, and three intense infrared -to-visible upconversion emissions at 524, 546 and 668 nm, corresponding to 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F11/2→4I15/2 transitions of Er3+ ions, respectivel y, have been observed under 977 nm excitation and the mechanisms involved have b een explained. The intensity parameters Ωt (t=2,4,6) of Er3+-doped TeO2-ZnO-PbCl2 oxyhalide glasses have been calculated according to the Judd- Ofelt theory, and the results are Ω2=59×10-20cm2，Ω4=2 1×10-20cm2，and Ω6=12×10-20cm2，respectively. The e mission cross_section has also been calculated from the absorption cross-section and the emission spectrum by using the McCumber theory. The maximum emission cr oss_section is 875×10-21cm2 at 153μm. Our results indicate that Te O2_ZnO_PbCl2 oxyhalide glasses are promising candidates for optical amplifie rs and upconversion lasers in comparison with the glasses such as silicate, phos phate, and fluoride glasses.