Energy Transfer Of Tm3 Research Articles

Tunable light emission mediated by energy transfer in Tm3+/Dy3+ co-doped LaF3 nanocrystals under UV excitation

Tm3+/Dy3+ co-doped LaF3 nanocrystals have been synthesized by the co-precipitation method and the luminescence properties under UV light excitation examined. Tunable light emission containing blue (450nm), yellow (570nm), and red (660nm) light components was observed. The excitation spectrum was investigated and the optimum excitation UV wavelength determined. The excitation mechanism responsible for the generation of the multicolor emission indicated that Tm-Dy energy-transfer plays a major role in the process. Tuning of the overall white-light emission was accomplished via variation of the Tm and Dy active ions contents in the nano-powder samples. The CIE chromaticity coordinates show that the Tm3+/Dy3+ co-doped LaF3 may be an excellent candidate for white light emitting diode devices.

Energy transfer, optical and luminescent properties in Tm3+/Tb3+/Sm3+ tri-doped borate glasses

Tm3+/Tb3+/Sm3+ tri-doped transparent borate glasses were successfully synthesized via melt quenching technique, and the optical and luminescent properties were characterized by photoluminescence excitation, photoluminescence spectra, absorption spectra, decay time and chromaticity coordinates. The energy transfer of Tm3+, Tb3+ → Sm3+ in Tm3+/Tb3+/Sm3+ co-doped glass samples was demonstrated. The chromaticity coordinate (x = 0.3339, y = 0.3241) and color correlate temperature (CCT = 5420.73 K) close to the standard white light (x = 0.3333, y = 0.3333 and CCT = 5454.12 K) could be achieved in 0.4Tm3+/1.0 Tb3+/0.8Sm3+ (mol %) tri-doped glass sample. It is expected that the investigated glasses may be a promising candidate for white-light-emitting diodes, luminescent materials and fluorescent display devices.

Tunable luminescence properties and energy transfer of Tm3+, Dy3+, and Eu3+ co-activated InNbO4 phosphors for warm-white-lighting

A series of Dy3+/Tm3+ singly-doped, Dy3+/Tm3+ co-doped, and Dy3+/Tm3+/Eu3+ tri-doped InNbO4 phosphors have been synthesized by a high-temperature solid-state reaction method. Powder X-ray diffraction (XRD), structure refinement, UV–visible diffuse reflectance (UV-DR) spectrum, photoluminescence excitation (PLE) and emission (PL) spectrum, decay lifetimes and CIE chromaticity coordinate were employed to understand the origins of luminescence properties for synthesized phosphors. Rare-earth activators were determined to be completely dissolved into the host lattice and occupied the 2e sites deviated from an inversion center by virtue of XRD, structure refinement and photoluminescence features. The photoluminescence excitation spectra of phosphors exhibited a broad excitation band ascribed to charge-transfer of O2−-Nb5+, ranging from 200 to 300nm, and some characteristic excitation peaks associated with energy level transition of RE ions. Under the excitation of UV light, phosphors presented characteristic emission originating from f-f transition within the 4f configuration of RE ions. With increasing Dy3+ concentration, emission colors of InNbO4:Tm3+, Dy3+ phosphors can be appropriately tuned from blue to yellow, including almost all the white light region, by means of energy transfer from Tm3+ to Dy3+. Energy transfer rates and efficiencies were calculated according to decay lifetimes and energy transfer mechanism followed a resonant type dipole-dipole interaction with critical distance of 22.23Å between Tm3+ and Dy3+. By compensating a red component of Eu3+ ion, single-component warm-white-light emitting was realized in InNbO4:Tm3+,Dy3+,Eu3+ phosphors. They might be promising candidates for color-tunable light-conversion components in the fabrication of ultraviolet-pumped warm-white-light emitting diodes (WLEDs) for solid-state lighting. Relationship of crystal structures and luminescence properties for InNbO4 and YNbO4 phosphors is as well explicated based on structural analysis.

Vis–NIR luminescence emission via energy-transfer in Tm3+/Er3+ and Tm3+/Nd3+ codoped glass under 1.319 µm excitation

Emission of visible and NIR frequency upconversion luminescence light mainly within the first biological window spectral region using excitation at 1319nm in the second biological window in Tm3+/Er3+-codoped TeO2-based glass, is demonstrated. For Tm3+/Er3+-codoped tellurite glass samples, green(525, and 550nm), red(660nm) and NIR(980nm) owing to erbium ions in addition to the main 800nm signal originating from thulium ions is readily observed. Here, energy-transfer Tm3+[3F4]+Er3+[4I15/2]→Tm3+[3H6]+Er3+[4I9/2] producing the NIR emission, followed by excited-state absorption of 1.319µm photons populating 2H11/2, 4S3/2, and 4F9/2 visible emitting levels. Erbium single-doped samples did not exhibited visible detectable emissions for excitation powers as high as 1.8W of cw radiation at 1.319µm. In Tm3+/Nd3+-codoped samples, energy-transfer from Tm3+ (3H6–3F4) to Nd3+ ions populates the 4F3/2 excited-state level producing NIR emission around 880nm.

Up-conversion luminescence properties and energy transfer of Tm3+/Yb3+ co-doped BaLa2ZnO5

Tm3+/Yb3+ co-doped BaLa2ZnO5 up-conversion (UC) phosphors were successfully synthesized by high temperature solid-state reaction method. The X-ray diffraction (XRD) results show that synthesized phosphor co-doped with 0.75% Tm/10% Yb has the optimum pure phase of BaLa2ZnO5 among different co-doping concentrations. The structure of BaLa2ZnO5:0.75% Tm/10% Yb phosphor was refined by the Rietveld method and results show the decreased unit cell parameters and cell volume after doping Tm3+/Yb3+, indicating that Tm3+/Yb3+ have successfully replaced La3+. Under excitation at 980nm, Tm3+/Yb3+ co-doped BaLa2ZnO5 phosphors present bright blue emission near 478nm generated by the 1G4→3H6 transition and weak red emissions around 653nm and 692nm generated by the 1G4→3F4 and 3F3→3H6 transitions of Tm3+, respectively. The UC luminescence properties of BaLa2ZnO5 phosphors co-doped with different Tm3+/Yb3+ concentrations were investigated, and the related UC mechanisms of Tm3+/Yb3+ co-doped BaLa2ZnO5 depending on pump power were studied in detail.

Luminescence and energy transfer of Tm3+ or/and Dy3+ co-doped in Sr3Y(PO4)3 phosphors with UV excitation for WLEDs

Powder samples Sr3Y1−x−y(PO4)3:xTm3+-yDy3+ were synthesized by the conventional solid-state reaction method. By appropriate tuning of activator content, the emission color can be adjusted around blue to white and yellow. It was discovered that the energy transfer from Tm3+ to Dy3+ was demonstrated to be via the intensity of Dy3+ emission increase with the increase of Tm3+ concentration. By changing the doping concentration of Tm3+ and Dy3+ in Sr3Y(PO4)3, white-emitting phosphors are produced by 350nm excitation wavelength, their corresponding color coordinates are very close to the white color chromaticity coordinates (x=0.33, y=0.33). Finally, Sr3Y1−x−y(PO4)3:xTm3+−yDy3+ phosphors could be a good promising single-component white light-emitting UV-convertible phosphor in the field of white LEDs.

Color-tunable emission and energy transfer in Tm3+/Dy3+/Sm3+ tri-doped phosphate glass for white light emitting diodes

Re3+ (Re3+=Tm3+, Dy3+, Sm3+) ions doped phosphate glasses for white light emitting diodes (W-LEDs) are successfully prepared by the high-temperature melting method. The luminescence properties of the glasses were characterized by the emission and excitation spectra. When excited by ultraviolet light Tm3+ ions single doped, Dy3+ ions single doped, and Sm3+ ions single doped phosphate glass emit blue, green and red light, which give the characteristic transitions of Tm3+ ions (1D2→3F4), Dy3+ ions (4F9/2→6H13/2,15/2), and Sm3+ ions (4G5/2→6H7/2,9/2), respectively. Moreover, there exists simultaneous luminescence of Tm3+, Dy3+, Sm3+ ions individually when co-doping them in the single phased phosphate glass (for example, Tm3+/Sm3+ ions co-doped; Dy3+/Sm3+ ions co-doped; Dy3+/Tm3+ ions co-doped; Tm3+/Dy3+/Sm3+ ions tri-doped systems), which is beneficial to tune the emission colors. Under the 360nm excitation, the CIE coordinates of Tm3+/Dy3+/Sm3+ ions tri-doped samples are close to the standard equal energy white light illumination (x=0.333, y−0.333). With an increasing in Sm3+ ions concentration, blue and green emissions decrease gradually while red emission increases. In addition, the energy transitions among Tm3+, Dy3+, and Sm3+ ions are discussed in detail. The phenomenon is reasonably interpreted based on the analysis of the luminescence lifetime.

Cooperative energy transfer in Tm3+ and Yb3+ co-doped phosphate glasses

An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+ to Yb3+ ions. Judd-Ofelt (J-O) theory was used to calculate the intensity parameters (Ω2, Ω4, Ω6), the radiative transition rates (Ar), and radiative transition lifetime (τrad) of Tm3+. Based on Inokuti-Hirayama's model, the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system. Quantum efficiency related to Yb3+ concentration was calculated, and the maximum QE efficiency reached 169.8%.

Facile fabrication and spectroscopic study of the energy transfer effect of Pr3 + and Tm3 + codoped La2O3 nanorod arrays

Pr3+ and Tm3+ codoped La2O3 nanorod arrays were synthesized firstly by electrochemical deposition and followed by calcination of the precursor at 700°C. The nanorods typically have an average diameter of 30–50nm and hexagonal structure. Bright photoluminescence at around 455nm, 495nm and 658nm is obtained in Tm3+ and Pr3+ codoped hexagonal La2O3 nanorods that is prepared by electrochemical methods method. Using 355nm laser to pump the codoped nanocrystal samples, we successfully observed the fluorescence emission originating from the energy transfer of Tm3+ to Pr3+. The luminescence properties and the mechanism of the energy transfer are investigated with laser spectroscopy.

Mid-infrared luminescence and energy transfer of Tm3+/Yb3+ doped fluorophosphate glass

Tm3+/Yb3+-codoped fluorophosphate glass is prepared by conventional melt-quenching method and the thermal stability of the glass is analyzed. The Judd–Ofelt parameters, radiation emission rates, radiative lifetime and branching ratios of prepared samples are calculated based on the absorption spectra. Upon excitation of a conventional 980nm laser diode, 1.8μm emission is obtained from Yb3+/Tm3+ codoped fluorophosphate. Additionally, the energy transfer between Yb3+ and Tm3+ ions are quantitatively analyzed. Hence, this Yb3+/Tm3+ codoped fluorophosphate glass possessing high energy transfer efficiency and excellent thermal stability is a good candidate for efficient 1.8μm laser.

Broadband near-infrared photoluminescence and energy transfer in Tm3+/Er3+-codoped low phonon energy gallate bismuth lead glasses

Tm3+/Er3+-codoped gallate bismuth lead (GBL) glasses are prepared and characterized optically. Broadband near-infrared fluorescence spectra composed of Er3+ 1.53 µm emission from the 4I13/2 → 4I15/2 transition and Tm3+ 1.47 µm emission from the 3H4 → 3F4 transition are recorded under 793 nm excitation wavelength. The full-width at half-maximum of the broad emission band depends on the Tm3+–Er3+ concentration ratio ([Tm]/[Er]), and a maximum bandwidth of 165 nm is achieved when the concentration ratio reaches 4, and the lineshape characteristic of the broadband emission remains the same for a fixed concentration ratio. The energy transfer processes involved are proposed and discussed, and the primary processes responsible for the flat broadband emission can be ascribed to the [Tm3+(3H4) + Tm3+(3H6)] → [Tm3+(3F4) + Tm3+(3F4)] and [Tm3+(3H4) + Er3+(4I15/2)] → [Tm3+(3F4) + Er3+(4I13/2)] processes. An investigation on energy transfer with assistance of matrix phonons shows that the matrix phonons play an important role in bridging the energy gap in the energy transfer processes.

Photoluminescence and energy transfer of Tm3+ doped LiIn (WO4)2 blue phosphors

Abstract Room temperature steady and time resolved emission spectra of LiIn1−xTmx(WO4)2 (where thulium concentration is 0, 0.5, 1, 5 and 10 at%) blue phosphors, under UV excitation energy have been investigated. The concentration quenching effect on the blue emission, due to the (WO4)−2 groups and 1G4→3H6 emission transition of Tm3+ were studied. Two energy transfer mechanisms are shown. The first takes place between excited (WO4)−2 groups and the 1G4 energy level of Tm3+, and is mainly analyzed by phonon-assisted energy transfer. The second mechanism is due to an energy transfer from the excited Tm3+ ions to the surrounding ground state Tm3+ ions. The non-exponential decay curves of the 1G4 level observed for higher concentrations are analyzed by the Inokuti–Hirayama model. We think that the quenching effect between Tm3+ ions is mainly linked to the dipole–dipole interactions.

Near-infrared emission properties and energy transfer of Tm3+-doped and Tm3+/Dy3+-codoped chalcohalide glasses

Near-infrared emission properties of Tm3+ in GeSe2–Ga2Se3–CsI glasses were investigated. The increase in emission intensity ratio I1.47 μm/I1.22 μm and the large increase in the lifetime of the Tm3+:H34 level from 189 to 2480 μs can be obtained as CsI concentration changes from 20% to 40%. These improved emission properties result from the appearance of I-containing structural units, which have low phonon energy and are located near the Tm3+ ions, dominating the multiphonon relaxation and cross relaxation. Radiative parameters of Tm3+ were calculated based on the Judd–Ofelt analysis. The potential use of Tm3+-doped GeSe2–Ga2Se3–CsI glasses for S-band fiber amplifiers was discussed. Additionally, the intensity and lifetime of 1.2, 1.3, and 1.47 μm infrared fluorescence on Tm3+/Dy3+-codoped GeSe2–Ga2Se3–CsI glasses were studied, and the energy transfer mechanisms were discussed.

2.0 μm emission properties and energy transfer of Tm3+/Ho3+-codoped tellurite glass

This paper reports on spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped ZnO-WO3-TeO2 glass upon excitation of 808nm diode laser. The J-O strength parameters， spontaneous emission probability and radiative lifetime of Ho3+ were calculated using Judd-Ofelt theory. The absorption cross-section and stimulated emission cross-section were also investigated. Our result indicates that the highest gain of 2.0 μm emission, which comes from 5I7 to 5I8 transition of Ho3+, might be achieved from the glass at the rare-earth ion concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. It is found that coefficients of the forward Tm3+→Ho3+ energy transfer is about 18 times that for the backward Tm3+←Ho3+ energy transfer. The calculated fluorescence lifetime of the 5I7 level of Ho3+ is 3.9 ms and the emission cross section of the 5I7→5I8 transition of Ho3+ exhibits a maximum of 9.15×10-21 cm2 at 2027 nm. We also found that Tm3+/Ho3+-codoped tellurite glass is a promising host material for potential 2.0 μm laser by comparing the quantum efficiencies, the values of σe×τm and gain coefficients of fluoride and heavy metal oxide glasses respectively.

Spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped Ga2O3-Bi2O3-GeO2-PbO-PbF2 glasses for 1.47μm luminecence

This paper reports on the spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped 14Ga2O3-25Bi2O3-20GeO2-31PbO-10PbF2 glasses. The Judd-Ofelt intensity parameters Ωt(t=2，4，6), spontaneous-emission probability, branch ratio and radiative lifetime of each level of Tm3+ have been calculated by Judd-Ofelt theory. The effective bandwidth and peak emission cross-section of the 3H4→3F4 transition (1.47μm) of Tm3+ have also been obtained. Codoping of Ho3+ significantly decreased the population of 3F4 level of Tm3+, while the population of 3H4 level of Tm3+ reduced slightly. Our results indicate that GGBPF glass is a promising candidate for 1.47μm optical amplifiers, and Ho3+ is an effective codopant to enhance the 1.47μm luminescence.

Optical spectroscopy and energy transfer inTm3+-doped metaphosphate laser glasses

Thulium-doped metaphosphate glasses with four concentrations (0.01, 0.1, 1.0 and 2.0 mol%) ofTm3+ have been prepared and investigated by Raman, absorption and photoluminescencespectral studies. The phonon sideband spectrum has been measured for 1.0 mol%Eu3+-doped metaphosphate glass of the same composition and compared withthe Raman spectrum. From vibronic spectra, various bands associated withdifferent structural groups have been identified and assigned. Absorption bandpositions have been used to simulate the complete energy level diagram for theTm3+ ion using the model Hamiltonian. Judd–Ofelt parameters have been determined from theabsorption bands. Using these parameters, transition probabilities, excited state lifetimesand transition branching ratios have been evaluated. The emission and decay curves of the1D2 levelhave been measured for all four glass samples both at RT and 15 K. Lifetimes show a strong quenchingfor Tm3+ concentrations higher than 0.1 mol%. Fluorescence decay curves of the1D2 level have been well fitted to the Inokuti–Hirayama model forS = 6, suggesting that the mechanism for energy transfer betweenTm3+ ions is of dipole–dipole type.

147-µm emission and multiphonon relaxation of Tm^3+ ions in potassium bismuth gallate glasses

We propose and demonstrate potassium bismuth gallate (KBG) glasses as suitable hosts for the rare-earth ion Tm3+ (thulium) operating at the 1.47-μm wavelength. The optical properties of Tm3+-doped KBG glasses were investigated. The bandwidth of the 3H4→3F4 transition is ∼120 nm and is higher than that of Tm3+-doped, tellurite-based glasses. The measured fluorescence lifetime is 0.15 ms at room temperature, and the quantum efficiency is 88%. Multiphonon relaxation rates for various transitions were evaluated and compared with other glass hosts. The energy transfer in Tm3+–Ho3+-codoped KBG glasses was also investigated, and these results indicate that Tm3+-doped KBG glasses are promising candidates for efficient broadband optical amplifiers operating in the 1.47-μm wavelength range.

Quantum efficiency of 1460 nm transition and energy transfer in Tm3+ doped glass

A self-calibrating quantum efficiency measurement technique is applied to the Tm3+ H43→F43 transition at 1460 nm. The method requires only relative fluorescence measurements to determine the absolute quantum efficiency. Overlapping spectral features are separated using phase-shifted fluorescence from different levels at high modulation frequency. The effect of energy transfer between Tm3+ ions is studied, and it is found that Tm3+ concentrations on the order of 1018 cm−3 are needed to avoid complications from Tm3+–Tm3+ cross relaxation. Application of the technique to Tm3+ doped fluorozirconate glass gives good agreement with the expected quantum efficiency based on multiphonon relaxation theory.

Effect of Tb3+ co-doping on the electron population densities of Tm3+ in Ge–As–Ga–S glasses

The 1.48-μm emission properties and electron population densities of the excited levels were investigated for Ge–As–Ga–S glasses doped with Tm3+ or Tm3+/Tb3+. Electron population inversion between the H43 and F43 levels in Tm3+ cannot be achieved without Tb3+ addition due to the strong cross-relaxation in Tm3+. Co-doping of Tb3+ resulted in the large decrease in the population density of the Tm3+:F43 level via the energy transfer of Tm3+:3F4→Tb3+:7F0,1,2. Calculated population densities of the two levels in Tm3+ using the rate equations showed that the population inversion became possible through the addition of Tb3+.

Selective sensitization of 480-nm blue upconversion by Tm3+-Er3+ energy transfer in tellurite glass

Blue upconversion luminescence at 480 nm resulting from Tm3+:1G4 → 3H6 by 650-nm pumping was selectively sensitized with Er3+ codoped in a tellurite glass. Codoping of Er3+ also quenched the 1D2 → 3F4 luminescence at 450 nm, leading to a single-line blue upconversion. To investigate this sensitized upconversion mechanism, the excitation spectra and the concentration dependence of the lifetimes of the Tm3+ and the Er3+ levels were measured for various doping levels. The Tm3+:3H4 level, which is the intermediate level of excited-state absorption to 1D2, to was found to be depopulated by the energy transfer of Tm3+:3H4 → Er3+:4I9/2 and the Tm3+:3F4 level, which is the intermediate level of excited-state absorption to 1G4, was found to be sensitized by the Er3+:4I13/2 → Tm3+:4F4 energy transfer. The concentration dependence of the transfer rate and of the efficiency of related levels was obtained, and it was concluded that the codoped Er3+ ion is a selective sensitizer in terms of quenching 1D2 upconversion and activating 1G4 upconversion by acting as an acceptor or as a donor for the initial level of each excited-state absorption of the Tm3+ ion.