Absorption Spectra Of Er3 Research Articles

High emission cross-section Er3+-doped fluorophosphate glasses for active device application

The fluorophosphate (FP) glasses modified with different concentrations of Mg(PO3)2 and ErF3, were synthesized by simple melt-quenching technique. The effect of Mg(PO3)2 addition on structural and spectroscopic properties of the Er3+-doped FP glasses were explored. The glass stability factor was determined from thermal analysis that showed that the prepared glasses possessed greater stability above >100 °C. The Raman analysis was carried out in order to know the vibrational groups in the fabricated glasses. In order to study the local structure and covalency between Er3+ ions and ligand environment, the Judd-Ofelt parameters were derived by Judd-Ofelt theory from the absorption spectra of Er3+-doped FP glasses. The emission spectra showed an intense and broadband at 1532 nm originating from 4I13/2→4I15/2 transition of Er3+ ion upon 980 nm diode laser excitation. The larger emission cross-section of 2.15 × 10−20 cm2 and an extensive lifetime of 12.50 ms, respectively, were noticed for 3 mol% ErF3 and 40 mol% Mg(PO3)2 based FP glass. Considering those results, studied Er3+-doped FP glasses have a feasibility to be used as active media for solid-state lasers and optical amplifiers at 1532 nm.

Further studies of radiation trapping in Er3+ doped chalcogenide glasses

Strong overlap of emission and absorption spectra of Er3+ doped glasses gives rise to effect of radiation trapping (RT) where the quanta are emitted, absorbed and re-emitted many times before leaving the volume of the material. We investigate the steady-state and transient PL of Er3+ ions embedded in gallium lanthanum sulphide-oxide glasses with partial substitution of sulfur by oxygen. We develop a technique for direct observation of RT and we show that RT combined with internal reflections leads to uniform spatial distributions of radiation and excited Er3+ ions inside of glass sample.

Optical spectroscopy, energy upconversion, and white-light emission characteristics of erbium-doped calcium fluoride crystal

Absorption spectrum of Er3+-dopedCaF2 revealed absorption peaks at 255, 365, 379, 407, 441, 449, 487, 522, 539, 652, and 798 nm. When the sample was excited with an 802-nm near-infrared laser, it revealed emissions at 390, 415, 462, 555, 665, and 790 nm due to stepwise excitation and energy transfer upconversion processes. The absorption and emission peaks are identified with Er3+ spectral transitions. The sample color appears to be either white or green under near-infrared laser excitation. Emission color was found to be dependent on the pump laser wavelength used and laser power. Excitation spectral recordings were made by tuning the pump laser wavelength. Excited state lifetimes are measured to analyze the data. Color coordinates and color temperatures are measured for 802- and 405-nm laser excitations. Our studies indicate that this sample is useful for solid-state lighting applications.

Judd-Ofelt analysis and temperature dependent upconversion luminescence of Er3+/Yb3+ codoped Gd2(MoO4)3 phosphor

Although lanthanide doped luminescent materials have been extensively investigated, a quantitative analysis of how temperature affects upconversion luminescence is still incomplete. The Gd2(MoO4)3:Er3+/Yb3+ phosphor is synthetized by sol-gel method. Based on the absorption spectra of Er3+ ions, J-O intensity parameters and radiative transition probabilities are computed to estimate the optical properties. In view of ion-phonon interaction, the phonon-assisted energy transfer and multiphonon relaxation are responsible for the temperature dependent luminescence. Additionally, cross relaxation probability for 4I11/2+4I11/2→4I15/2+4F7/2 is determined to be 240s−1 through quantitative simulation of ion-ion interaction. These meaningful results are of vital values for the field of laser crystal and optical temperature sensing.

Judd–Ofelt analysis of ceramic La3Ga5.5Ta0.5O14 doped with Er3+

A Judd–Ofelt analysis is performed on ceramic samples of erbium-doped langatate (La3Ga5.5Ta0.5O14 – LGT). The intensity parameters are calibrated using the lifetime of the radiative-decaying 4I13/2 level. The influence of the light scattering on the absorption spectra of Er:LGT and implicitly on the intensity parameters is investigated by changing the sample thickness. The value of the Ω2 parameter was found to be more sensitive to light scattering effects, while Ω6 is the most insensitive to such effects. The quantum efficiency of the (2H11/2, 4S3/2) and 4F9/2 levels was calculated; their values are only slightly distorted in the presence of light scattering. The possibility of erroneous interpretations of the Judd–Ofelt parameters due to light scattering effects is pointed out.

Fluorescence and Judd-Ofelt Analysis of Er<sup>3+</sup> Doped CaF<sub>2</sub> Transparent Ceramic

In this paper, we evaluated the spectra parameters of Er3+.The absorption spectra of Er3+:CaF2transparent ceramic was measured at room temperature (RT). Based on the Judd–Ofelt theory, the intensity parameters were Ω2= 5.02×10−20cm2, Ω4= 3.40×10−20cm2and Ω6= 0.38×10−20cm2, and then the values of the radiative transition probabilities, radiative lifetimes and integrated emission cross-sections of excited states were calculated. Full width at half maximum (FWHM) of the fluorescence spectra for4I13/2→4I15/2transition was investigated, being 17nm. The decay time was found to be 24.3ms, which is longer than the theoretically calculated value indicating a radiation trapping effect in this work.

Enhanced infrared to visible upconversion emission in Er3+ doped phosphate glass: Role of silver nanoparticles

Phosphate glasses with compositions (59.5–x)P2O5–MgO–xAgCl–0.5Er2O3 (0.0≤x≤1.5mol%) containing fixed concentration of Er3+ ion with and without silver nanoparticles (NPs) are prepared using melt quenching technique. The amorphous nature of the glass is confirmed using the X-ray diffraction method. The homogeneous distribution of spherical Ag NPs (average size ∼37nm) in the glassy matrix is evidenced from the transmission electron microscopy (TEM) analyses. The UV–vis–NIR absorption spectra shows 10 bands corresponding to 4I13/2, 4I11/2, 4I9/2, 4F9/2, 4S3/2, 2H11/2, 4F7/2, 4F5/2, 2G9/2, 4G11/2 transitions in which the most intense bands are 2H11/2 and 4G11/2. The absorption spectrum of Er3+ ions free glass sample containing Ag NPs displays a prominent surface Plasmon resonance (SPR) band located at 528nm. The infrared to visible frequency upconversion (UC) emission under 797nm excitation shows two emission bands green (4S3/2–4I15/2) and red (4F9/2–4I15/2) centered at 540nm and 634nm, respectively, corresponding to Er3+ transitions. An enhancement in UC emission intensity of green band (4S3/2–4I15/2) is observed in the presence of silver NPs and the maximum enhancement occurred for 1.5mol% AgCl. However, the enhancement of emission intensity of the red band (4F9/2–4I15/2) is smaller. The enhancement of UC emission is understood in terms of the intensified local field effect due to silver NPs.

Synthesis, characterization, optical absorption, luminescence and defect centres in Er3+ and Yb3+ co-doped MgAl2O4 phosphors

The Er3+–Yb3+ co-doped MgAl2O4 phosphor powders have been prepared by the combustion method. The phosphor powders are well characterized by X-ray diffraction (XRD) and energy dispersive (EDX) techniques. The absorption spectrum of Er3+/Er3+–Yb3+ doped/co-doped phosphor powder has been recorded in the UV–Vis–NIR region of the electro-magnetic spectrum. The evidence for indirect pumping under 980 nm excitation of Er3+ from Yb3+ was observed in the MgAl2O4 matrix material. Electron spin resonance (ESR) studies were carried out to identify the defect centres responsible for the thermally stimulated luminescence (TSL) process in MgAl2O4:Er3+ phosphor. Three defect centres were identified in irradiated phosphor by ESR measurements which were carried out at room temperature and these were assigned to an O− ion and F+ centres. O− ion (hole centre) appears to correlate with the low temperature TSL peak at 210 °C and one of the F+ centres (electron centre) is related to the high temperature peak at 460 °C.

Bridgman crystal growth and spectral properties of Er doped PbWO4 as stimulated Raman crystals

Several Er doped (0.2at%, 0.5at%, and 1.0at%) PbWO4 single crystals were grown by Bridgman method with the size of Φ20×100mm. The absorption spectra of Er:PWO samples were measured to investigate the spectral properties of Er3+ ions according to Judd-Ofelt theory. The phenomenological intensity parameters Ωλ were fitted to calculate the spectral parameters of several radiative transitions of Er3+ ions, and the possibility of 4I13/2→4I15/2 transition at about 1.5μm of Er3+ ions in PWO crystal was also discussed. The energy transfer from PWO matrix to Er3+ ions was investigated based on the photoluminescence spectra, and the frequency shifting effect of Er3+ ions on PWO crystal was discussed according to the spontaneous Raman spectra. The 1.5μm fluorescence spectra of different Er:PWO samples were measured under the excitation at 980nm.

Optical Properties of LaF3:Er,Yb Nanoparticle-Doped Organic–Inorganic Hybrid Material

Oleic acid (OA)-modified LaF3:Er,Yb nanoparticle-doped organic-inorganic hybrid material (OIHM) was prepared. The absorption spectrum and photoluminescence spectrum were analyzed. The full width at half maximum (FWHM) of the photoluminescence spectrum was about 83 nm. The Judd-Ofelt theory was used to analyze the absorption spectrum of Er3+ and obtain the intensity parameters: omega2 = 2.11 x 10(-20) cm2, omega4 = 0.78 x 10(-200 cm2, omega6 = 0.56 x 10(-20)cm2. The line strengths predict spontaneous transition probabilities, and the radiative lifetimes are calculated with the Judd-Ofelt intensity parameters. The calculated radiative lifetime of the excited 4I13/2 state of Er3+ is 13.34 ms. Based on the parameters we calculated, OA-modified LaF3:Er,Yb nanoparticle-doped OIHM is a potential material for polymeric optical waveguide amplifiers.

Study of absorption spectra of Er3+ in KTaO3 crystals

The first results of the study of optical absorption spectra of KTaO3: Er3+ crystals are presented. In the 350–660-nm region, lines are observed deriving from intraconfigurational electronic transitions from the 4I15/2 ground state to levels of the 4F9/2, 4S3/2, 2H11/2, 4F7/2, 4F5/2(4F3/2), 2G9/2, and 4G11/2 excited states of the Er3+ ions. A comprehensive study of transitions to the 4F9/2, 4S3/2, 2H11/2, and 4F7/2 levels at 77 K is carried out. The number of lines observed for the above transitions fits the theoretically possible number for ƒ-ƒ electronic transitions in Er3+ ions in the cubic crystal field. In the case of a differently charged substituted ion, this situation occurs only under nonlocal impurity charge compensation. The energies of the excited state levels for the transitions under study are determined.

Bimetallic Pt(II)-bipyridyl-diacetylide/Ln(III) tris-diketonate adducts based on a combination of coordinate bonding and hydrogen bonding between the metal fragments: Syntheses, structures and photophysical properties

The luminescent Pt(II) complex [Pt(4,4′- t Bu 2-bipy){CC-(5-pyrimidinyl)} 2] ( 1) was prepared by coupling of [Pt(4,4′- t Bu 2-bipy)Cl 2] with 5-ethynyl-pyrimidine, and contains two pyrimidinyl units pendant from a Pt(II) bipyridyl diacetylide core; it shows luminescence at 520 nm which is typical of Pt(II) luminophores of this type. Reaction with [Ln(hfac) 3(H 2O) 2] (hfac = anion of hexafluoroacetylacetone) affords as crystalline solids the compounds [ 1 · {Ln(hfac) 3(H 2O)}{Ln(hfac) 3(H 2O) 2}] (Ln = Nd, Gd, Er, Yb), in which the {Ln(hfac) 3(H 2O)} unit is coordinated to one pyrimidine ring via an N atom, whereas the {Ln(hfac) 3(H 2O) 2} unit is associated with two N atoms, one from each pyrimidine ring of 1, via N⋯HOH hydrogen-bonding interactions involving the coordinated water ligands on the lanthanide centre. Solution spectroscopic studies show that the luminescence of 1 is partly quenched on addition of [Ln(hfac) 3(H 2O) 2] (Ln = Er, Nd) by formation of Pt(II)/Ln(III) adducts in which Pt(II)→Ln(III) photoinduced energy-transfer occurs to the low-lying f–f levels of the Ln(III) centre. Significant quenching occurs with both Er(III) and Nd(III) because both have several f–f states which match well the 3MLCT emission energy of 1. Time-resolved luminescence studies show that Pt(II)→Er(III) energy-transfer (7.0 × 10 7 M −1) is around three times faster than Pt(II)→Nd(III) energy-transfer (≈2 × 10 7 M −1) over the same distance because the luminescence spectrum of 1 overlaps better with the absorption spectrum of Er(III) than with Nd(III). In contrast Yb(III) causes no significant quenching of 1 because it has only a single f–f excited level which is a poor energy match for the Pt(II)-based excited state.

Analysis of the dynamics of upconversion in erbium-doped transparent lead lanthanum zirconate titanate ceramic

The absorption and upconversion fluorescence spectra of Er3+ ions in Er3+ doped transparent lead lanthanum zirconate titanate(PLZT)ceramic were measured at room temperature. The radiative transition probabilities of the Er3+ ions were calculated using the absorption spectrum of Er3+ doped PLZT. Strong upconversion emission was observed in the upconversion luminescence of Er3+ doped PLZT. The green emission intensities at 540nm and 564nm were stronger than the red emission intensity at 678nm. The upconversion rate equations describing the dynamic process of the system have been deduced. The upconversion coefficients were estimated by numerically solving the rate equations and fitting the simulated curves to the measured data. The coefficients C22and C33 obtained are 091×10-18cm3/s and 1823×10-18cm3/s, respectively. The results show that evident upconvesion phenomenon can be observed in Er3+: PLZT transparent ceramics, which is consistent with our observation.

Optical characterization and ligand-field splitting of Er3+(4f11) energy levels in a fluorine containing tellurite glass

An in-depth spectroscopic study is performed on Er3+(4f11) ions doped into a fluorine containing (lead, lanthanum)-tellurite glass host, containing nominal 1.93at.% of Er3+. The standard Judd-Ofelt (JO) model is applied to the room temperature absorption intensities of Er3+(4f11) transitions in the tellurite glass host to obtain three phenomenological intensity parameters, Ω2, Ω4, and Ω6. These parameters are subsequently used to determine the radiative decay rates, radiative lifetimes, and branching ratios of the Er3+ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds LJ2S+1 of Er3+(4f11) in the tellurite glass host. The emission cross sections of the intermanifold Er3+ I13∕24→I15∕24 (1.5μm) and S3∕24→I15∕24 (540nm) transitions have been determined. The room temperature fluorescence lifetimes of the I13∕24→I15∕24 and S3∕24→I15∕24 transitions in this tellurite glass host were also measured. From the radiative lifetime determined from the JO model and measured fluorescence lifetime, the quantum efficiency of this material was also determined. The spectroscopic properties were compared with those of Er3+(4f11) in other halotellurite glass hosts. We also analyzed the band structure observed in the absorption spectra of Er3+ in the tellurite glass at 8K. The structure can be interpreted in terms of the ligand-field splitting of the energy levels of the Er3+ ion in the local environment established by the glass matrix into which Er2O3 has been introduced. The spectroscopic analysis of Er3+(4f11) suggests that the tellurite glass is an excellent candidate for various photonic applications.

Effect of radiation trapping on the emission properties of Er 3+: 4I 13/2 → 4I 15/2 transition in oxide glasses

The effect of radiation trapping on the emission properties of Er 3+-doped tellurite and phosphate glasses has been investigated as the function of sample thickness and doping concentration. It was found that radiation trapping exists generally in two glass matrices, even at low doping concentration (⩽0.1 mol% Er 2O 3). The larger effect of radiation trapping in tellurite glasses compared with phosphate glasses is due to its larger emission cross-section at 1.5 μm band and the spectral overlap between the emission and absorption spectra of Er 3+: 4I 13/2 ↔ 4I 15/2transition. Due to radiation trapping, the measured lifetime of the Er 3+: 4I 13/2 level in tellurite glasses increases by about 11–37% with increasing the sample thickness at the different erbium doping concentration, while 6–17% for phosphate glasses. And the full-width at half maximum of fluorescence (FWHM) of Er 3+: 4I 13/2 → 4I 15/2 transition in tellurite glasses increased by about 15–64% with increasing the sample thickness, while 11–55% for phosphate glasses. It caused a high overestimation on the figure of merits (FOM) for amplifier bandwidth ( σ e × FWHM).

Optical properties of Er 3+/Yb 3+-codoped transparent PLZT ceramic

Optical absorption and emission spectra of Er 3+/Yb 3+ ions in PLZT (Pb 1− x La x Zr y Ti 1− y O 3) ceramic have been studied. Based on the Judd—Ofelt (J–O) theory, the J–O intensity parameters were calculated to be Ω 2=2.021×10 −20 cm 2, Ω 4=0.423×10 −20 cm 2, Ω 6=0.051×10 −20 cm 2 from the absorption spectrum of Er 3+/Yb 3+-codoped PLZT. The J–O intensity parameters have been used to calculate the radiative lifetimes and the branching ratios for some excited 4I 13/2, 4I 11/2, 4I 9/2 4F 9/2, and 4S 3/2 levels of Er 3+ ion. The stimulated emission cross-section (8.24×10 −21 cm 2) was evaluated for the 4I 13/2→ 4I 15/2 transition of Er 3+. The upconversion emissions at 538, 564, and 666 nm have been observed in Er 3+/Yb 3+-codoped PLZT by exciting at 980 nm, and their origins were identified and analyzed.

Electron‐phonon interaction in Er and Dy doped YAl3(BO3)4 single crystals

AbstractIn the present work high resolution Fourier Transform spectroscopy is applied to monitor the electron‐phonon (e–‐ph) interaction in YAB single crystals doped with trivalent Er and Dy ions. The electron‐phonon coupling is analysed by monitoring the shape, width, and position of the zero‐phonon lines induced by Er3+. The shift and broadening with temperature increasing are discussed in the framework of the two‐phonon Raman scattering. The e–‐ph interaction is revealed even by the presence, in the absorption spectra of Er and Dy doped YAB crystals, of new weak lines attributed to vibronic transitions. The energy separations between the vibronic and the ZP lines are compared with IR‐active modes measured on YAB crystals. Boron isotopic effects are also put in evidence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Judd–Ofelt intensity parameters of Er 3+ doped mixed alkali aluminophosphate glasses

Lithium sodium mixed alkali aluminophosphate glasses of the composition xNa 2O–(15 − x) Li 2O–4B 2O 3–11Al 2O 3–5BaO–65P 2O 5 (where x = 0, 3.75, 7.5, 11.25 and 15 mol%) containing 0.5 mol% Er 2O 3 were prepared by melt quenching. The absorption spectra of Er 3+ were studied from the experimental oscillator strengths and the Judd–Ofelt intensity parameters were obtained. The variations of Judd–Ofelt intensity parameters ( Ω 2, Ω 4 and Ω 6), experimental oscillator strengths of certain excited states of Er 3+ and hypersensitive band positions with different mixed alkali content have been discussed in detail. It was found that there were similar effects of mixed alkali on both Judd–Ofelt intensity parameter Ω 2 and the experimental oscillator strength of the hypersensitive transition, 4I 15/2 → 2H 11/2. No shifts in the peak wavelength of the studied transitions were found in different glasses.

Spectra and energy levels of Er 3+ in Er 2O 3 powder

The emission and absorption spectra of Er 3+ ions in Er 2O 3 powder are investigated at room temperature. The crystal field splitting of 4I 15/2, 4I 13/2, 4I 9/2 and 4S 3/2 multiplets of Er 3+ was calculated using a parameterized Hamiltonian including crystal field terms. A final standard deviation of 5.3 cm −1 is obtained between 22 calculated and experimental Stark. The strength crystal field parameters of Er 2O 3 powder are compared to those of erbium doped Y 2O 3 single crystal. In addition, the location of the ground and the first excited states of Er 3+ in Er 2O 3 powder is determined. The 4I 15/2 ground state of Er 3+ is located at 12750 cm −1 below the valence band edge. The 4I 13/2 and 4I 11/2 multiplets are set in resonance with the valence band. A configuration coordinate diagram is proposed for Er 3+ in Er 2O 3 powder.

Comparative study of spectroscopic properties of Er 3+ /Yb 3+ -codoped tellurite glass and fibres under 980nm excitation

A tellurite fibre of TeO2–ZnO–La2O3–Li2O glass codoped with 20000 ppm ytterbium and 5000 ppm erbium was fabricated by the suction casting and rod-in-tube technologies. The absorption spectrum of Er3+/Yb3+ -codoped bulk glass has been measured. From the Judd–Ofelt intensity parameters, the spontaneous emission probability and radiative lifetime τrad of Er3+:4I13/2→4I15/2 transition for the bulk glass have been calculated. The emission fluorescence spectra and lifetimes around 1.5μm and subsequent upconversion fluorescence in the range of 500–700nm were measured in fibres and compared with those in bulk glass. The changes in amplified spontaneous emission with fibre length and pumping power was also measured. It was found that the emission spectrum from erbium in fibres is almost twice as broad as the corresponding spectrum in bulk glass when pumped at 980nm.