Er Yb Research Articles

Structural and optical properties of ZnGa2−x(YbXCrGe)xO4 (X = Ho and Er) up-conversion photoluminescence materials

ZnGa2−x(YbXCrGe)xO4 (X = Ho3+, Er3+) compounds are prepared using the solid-state-reaction method. Alteration in the lattice parameters and strain signifies the substitutional doping of elements at the octahedrally coordinated Ga3+ ions. Down-shifting PL properties are observed at the excitation wavelength of 275 nm. NIR wavelength (980 nm) induced up-conversion PL is observed in the Yb and Ho and/or Er doped samples. The prominent green-colored emission is observed in Yb3+ and Ho3+ doped sample and intense red-colored emission is achieved in the Yb3+ and Er3+ doped sample. The existence of up-conversion photoluminescence is mechanistically discussed by considering the energy transfer processes among the Zn2+, Ga3+, Yb3+, Ge3+, Cr3+, Er3+, and Ho3+ ions.

Random laser emission at 1064 and 1550 nm in a Er/Yb co-doped fiber-based dual-wavelength random fiber laser.

Dual-wavelength fiber lasers operating with a wide spectral separation are of considerable importance for many applications. In this study, we propose and experimentally explore an all-fiberized dual-wavelength random fiber laser with bi-directional laser output operating at 1064 and 1550 nm, respectively. A specially designed Er/Yb co-doped fiber, by optimizing the concentrations of the co-doped Er, Yb, Al and P, was developed for simultaneously providing Er ions gain and Yb ions gain for RFL. Two spans of single mode passive fibers are employed to providing random feedback for 1064 and 1550 nm random lasing, respectively. The RFL generates 5.35 W at 1064 nm and 6.61 W at 1550 nm random lasers. Two power amplifiers (PA) enhance the seed laser to 50 W at 1064 nm with a 3 dB bandwidth of 0.31 nm and 20 W at 1550 nm with a 3 dB bandwidth of 1.18 nm. Both the short- and long-term time domain stabilities are crucial for practical applications. The output lasers of 1064 and 1550 nm PAs are in the single transverse mode operating with a nearly Gaussian profile. To the best of our knowledge, this is the first demonstration of a dual-wavelength RFL, with a spectral separation as far as about 500 nm in an all-fiber configuration.

Planar triangular lattice of the LuMgGaO4: Clustered site-occupancy and the upconversion luminescence of the co-doped Er,Yb ions

The ordered and stable structure of inorganic lattice is the basis of constructing high-efficiency rare earth activated fluorescence, solid-state laser or other optical materials. The mixed sensitized and activated rare earth ions usually keeps a uniform space-occupying and the energy transfer depends much on the doping concentration, while the aggregation of rare earth dopants in order is rare. In this work, a series of LuMgGaO4 phosphors were synthesized and the detail lattice parameters are analyzed through Vietveld refinement and the new CIF file is provided. The site-occupancy of Er3+, Yb3+ shows clustered features and the Er–Yb sublattice structure with various Yb/Er ratios were constructed on the basis of planar triangular lattice. The long-distance excitation energy migration to lattice or defects can be effectively inhibited in case of the hexagonal circle Er-6Yb sublattice, in which the most intense green/red UCL was obtained. All the results demonstrate the novelty of regulating ordered site-occupancy of rare earth ions on a compact planar triangular lattice with higher efficiency of energy migration, which will pave a way for developing phosphor-converted materials or laser materials with better performance.

Blue and green upconverted emission in fluoroindate glasses under 808 nm excitation

In this study, the upconversion (UC) luminescence of fluoroindate glasses (InF3G) co-doped with Yb-Nd-Er (Tm) ions excited in the NIR-I biological window was analyzed. In the first system, UC emission of singly Er3+ doped InF3G under 808 nm excitation occurred to be more efficient than those observed in InF3G co-doped with Yb–Er and Yb-Nd-Er. The intensity of UC emission (InF3G-Er) was 22 % higher than InF3G-Yb-Er, and even more than two times higher than in the InF3G-Yb-Nd-Er sample. The effective energy transfer (η) between Nd3+- Yb3+ (η = 45 %) and Yb3+-Er3+ (η = 68 %), was reflected in the emission observed in the NIR region mainly, ascribed to Yb3+:2F5/2 → 2F7/2 (978 and 999 nm) and Nd3+:4F3/2 → 4I9/2 (1053 nm) transitions. Meanwhile, the samples co-doped with Tm3+ exhibited a strong dependence on Yb-Nd-Tm co-doping. Samples without Yb and Nd did not exhibit any UC emission due to the absence of pumping channel. This contrasts with the downshifting NIR emission, which was at least two times higher than those exhibited in samples co-doped Yb-Nd-Er. These results suggest that Tm3+ plays a crucial role in populating the lower-lying exited levels of Yb and Nd, influencing the overall emission behavior.

Performance Enhancement of Er–Yb: Co-doped Waveguide Amplifier Employing Backward Pumping in the Presence of Energy Transfer Upconversion

Performance Enhancement of Er–Yb: Co-doped Waveguide Amplifier Employing Backward Pumping in the Presence of Energy Transfer Upconversion

Dual-wavelength excited luminescence properties of NaYbF4:Er3+ for flexible anti-counterfeiting

Multiple encryption of information is the key to the upgrade of anti-counterfeiting technology. However, developing reliable multimode anti-counterfeiting materials is still a challenging work. Herein, a series of Er-doped NaYbF4 microprisms was synthesized. The as-prepared microprisms could show variable emission from red to yellow under the irradiation of 980 nm, and exhibit red at 365 nm UV light, respectively. Near-infrared excitation is achieved through the upconversion process of Er–Yb pairs, while UV excitation is achieved through Er ions. Its crystal structure, morphology, and photoluminescence features were analyzed. To broaden its practical application, the powders were combined with TPU to form a film with excellent stretchability, transparency, and water resistance. Our work demonstrates a dual-wavelength excited luminescence material, providing a practical reference for the application of anti-counterfeiting materials.

Upconversion luminescence of La4Ti9O24: Er–Yb phosphor with high green color purity

Upconversion materials with high green color purity are considered to have greater potential in the development and manufacturing of modern optoelectronic devices. However, the generation of high green color purity in Er3+-Yb3+ ions doped upconversion materials is usually a great challenge. Herein, we develop a series of Er3+ singly doped, and Er3+-Yb3+ co-doped La4Ti9O24 phosphors with high green color purity under 980 nm irradiation. The green emission of the phosphor was not changed by increasing Yb3+ concentrations, and the material exhibited excellent color purity. We found that low phonon energy and layered structure are the main causes of high green color purity by analyzing Raman spectrum and crystal structure. Based on CIE chromaticity estimates from 1931 in terms of coordinates, dominant wavelength, and color purity, La4Ti9O24: 3 mol% Er3+ and La4Ti9O24: 3 mol% Er3+-16 mol% Yb3+ presents the color purity of 95.14% and 96.04%, respectively.

Boosting the 1540 nm near-infrared luminescence of Er3+ doped double perovskites via cross-relaxation and energy transfer

Rare earth (RE) doped lead-free double perovskites (DPs) are potential near-infrared (NIR) light source materials due to their non-toxicity, simple preparation and low price. In this work,Cs2Ag0.1Na0.9BiCl6 DPs were chosen as matrix materials and different RE ions (Eu3+/Yb3+/Tb3+) were co-doped with Er3+ ions to study the effective ways to further enhance the NIR luminescence of Er3+ at 1540 nm in DPs. It found that double-doping (Eu–Er, Tb–Er, and Yb–Er) can improve the 1540 nm emission of Er3+ in DPs through cross-relaxation (CR) and energy transfer (ET), respectively. For tri-doped samples (DPs-Yb-Eu-Er and DPs-Yb-Tb-Er), the CR process between the Eu3+ (Tb3+) and Er3+ ions and the ET process from Yb3+ to Er3+ ions enhance synergically the luminescence of Er3+ at 1540 nm. Under excitation at 365 and 980 nm, the luminescence enhancement of DPs-Yb-Eu-Er at 1540 nm is 6.2 and 45 times, respectively, compared with that of DPs-Er. At the excitation of 365 nm, the photoluminescence quantum yield (PLQY) of DPs-Yb-Eu-Er is 18.2%, which is the maximum efficiency recorded reported so far for micron level DPs. Finally, DPs-Yb-Eu-Er was embedded into a polymethyl methacrylate (PMMA) polymer matrix to form a NIR light-emitting diode (LED) device. Good night vision imaging and tissue penetration experiments were performed under the irradiation of this NIR LED. This work provided a new method for the design of RE doped lead-free DPs with effective NIR emission.

Boosting Photo Upconversion in Electropolymerised Thin Film with Yb/Er Complexes

AbstractUpconversion luminescence (UCL) in organometallic complexes has attracted great interest in photovoltaics and biological applications due to their fascinating energy transfer mechanism from low‐energy photon to high‐energy photon. However, photon‐upconversion operating in a single discrete entity remains a challenge caused by low‐absorption cross section of the luminescent lanthanide element. Here, a novel upconversion system is reported combining Yb (Ytterbium) sensitizers and Er (Erbium) activators in the film by electropolymerization, which leads to excited‐state absorption (ESA) and energy transfer upconversion (ETU) processes. For the first time, the UCL has been achieved in the thin films upon near‐infrared laser irradiation, and the upconversion intensity exhibits up to 30‐fold enhancement with the variation of Yb/Er ratio.

Upconversion luminescence studies in (Er3+, Yb3+, and Mo6+) tri-doped SrWO4 ceramics

Augmented sensitization in (Er3+, Yb3+, and Mo6+) tri-doped SrWO4 ceramic compositions is investigated, and the possible role of [Yb-MoO4]2- dimer formation is probed. Structural distortion in SrO8 deltahedron and WO4 tetrahedral units in SrWO4 due to Er–Yb ion substitution for Sr2+, and Mo6+ for W6+ is confirmed by Rietveld refinement of X-ray diffraction data. Evolution of defect induced phase depending on Mo6+ dopant concentration, and the formation of [Yb-MoO4]2- dimer is envisaged by Raman and infrared spectroscopy. Selective enhancement in the green emission band (530 nm) by ∼ 58 times is supported by [Yb-MoO4]2- dimer development, and the enhancement of up-conversion emission intensity is confirmed using excited state decay life time measurements.

Influence of Er and Yb on photoelectrochemical performance of TiO2 thin film

The strategy of modifying the titanium dioxide photoanode with an internal upconverter containing Er activator and Yb sensitizer was proposed. To assess the impact of rare earth ions, thin film TiO2, TiO2:Er, and TiO2:Er,Yb were deposited in the magnetron sputtering process on conducting glass, amorphous silica a-SiO2, and silicon. Two strategies were tested: introduction of high activator content and incorporation of low activator content with addition of sensitizer. Pure TiO2 served as a reference material. All deposited films displayed promising optical properties, such as high transparency and low reflectance in weak absorption region, and strong absorption above the fundamental absorption edge, as investigated by spectrophotometric measurements. Structural characterization by means of grazing incidence X-ray diffraction and transmission electron microscopy revealed that films crystallized as a mixture of anatase and rutile, while high concentration of modifying ions led to amorphization. Changes in surface morphology accompanied the structural transition, as shown in scanning electron microscopy analysis. Current-voltage and time-dependent measurements in photoelectrochemical cells, under white light illumination before and after cut-off of ultraviolet light, confirmed enhanced performance of TiO2:Er,Yb (1 at.%, 1 at.%) photoanodes over pure TiO2 as well as TiO2:Er (10 at.%) and TiO2:Er,Yb (2 at.%, 10 at.%).

Influence of NaYF4 Inert and Active Layer on Upconversion Luminescence.

NaYF4:Yb,Er@NaYF4 core–shell nanostructures were prepared to investigate their influence on upconversion (UC) luminescence. Tests revealed green radiation (4S3/2→4I15/2) and red radiation (4F9/2→4I15/2) first increased and then gradually decreased as Yb concentration increased in the NaYF4 shell. The strongest fluorescent radiation occurred at an Yb concentration of 5%. To investigate the complicated variation of luminescence, we designed a set of experiments to study the impact of Yb ion concentration on luminescence intensity, and we analyzed the corresponding enhancement mechanism. It is probable that the energy transfers between both Yb and Er ions and Yb and Yb ions are involved in the UC processes. The enhancement of hybrid nanostructures has huge potential in biological detection and solar cells.

A 102 W High-Power Linearly-Polarized All-Fiber Single-Frequency Laser at 1560 nm

A 1560 nm high-power linearly-polarized all-fiber single-frequency narrow-linewidth laser with near diffraction-limited beam quality is demonstrated. The Yb–Er energy transfer efficiency and the ability of the signal laser to capture pump light have been improved by specifically choosing the pumping wavelength and the input signal power in the final power amplifier stage of this laser system. Under the off-peak absorption pumping wavelength of 940 nm, along with the maximum input signal power of 6 W, a maximum output power of 102 W with a slope efficiency of 40.5% is acquired. At the highest output power status, a polarization extinction ratio (PER) of 15.5 dB, a linewidth of 3.05 kHz, and a beam quality of Mx2 = 1.14, My2 = 1.06 are obtained, respectively. This advanced single-frequency fiber laser has great potential for the long-range coherent Doppler lidar and the next generation of gravitational wave detection.

Effect of Yb[formula omitted] concentration on Er[formula omitted] doped CaF[formula omitted] single crystal for temperature sensor applications

Yb–Er co-doped CaF2 crystals with different Yb3+ ions concentrations are successfully grown by the temperature gradient technique (TGT) method. Up-conversion (UC) luminescence characteristics and optical temperature sensing behavior of all samples are thoroughly investigated in this work. Under the excitation of a 980 nm laser-diode, the up-conversion luminescence intensity firstly increases and then decreases. By adjusting the content of Yb3+ ions, multi-color visible light emissions of red, yellow and green could be easily obtained. The fluorescence intensity ratio from two thermally coupled 2H11/2 and 4S3/2 levels technology is used to evaluate the temperature sensing performance of Yb–Er co-doped CaF2 crystals. The concentration of Yb3+ ions shows a significant influence on the temperature sensing performance. The sensitivity reaches the maximum value of 2.24 × 10−3 K−1 at 548 K with a 5 at.% doping concentration of Yb3+ ions. The experiment also confirms that Yb–Er co-doped CaF2 crystal exhibit high stability as optical temperature sensors. In general, it is proved that Yb–Er​ co-doped CaF2 single crystals are a kind of promising materials used in the optical temperature sensor.

Facile synthesis and enhanced luminescence properties of Cu2-xS@YF3:Yb–Er core-shell nanoparticles

Up-converting luminescent nanoparticles (UCNPs) have been arousing increasing attention in biomedical imaging because of their long-life emission and concomitant benefits (e.g., zero-autofluorescence background, low toxicity). However, the further development on the application has been limited by the low luminescence efficiency and intensity of UCNPs. Herein we report the design principle, synthesis route, and luminescence properties of core-shell structured Cu2-x[email protected]3:Yb–Er nanoparticles with strong luminescent property (red emission). The design principle leverages on the plasmon-enhanced localized electric fields effect of the interface of Cu2-xS and YF3:Yb–Er nanoparticles and photo-thermal effect of Cu2-xS. This strategy could enhanced luminescence properties of YF3:Yb–Er nanoparticles. The as-prepared Cu2-x[email protected]3:Yb–Er nanoparticles possessed stronger luminescent property (red emission) than individually dispersed YF3:Yb–Er nanoparticles. And the nanoparticles presented a dramatic red-shift that was due to the growth of YF3:Yb–Er on the Cu2-xS surface. The research supplies an insight on the development of nonmetallic plasmon-sensitized luminescent materials, and hopefully it could promote them application in the diagnosis and treatment of cancer.

Correlation between local lattice distortions and up-/down-conversion luminescence of (Y,Al)NbO4:Yb3+/Er3+

The changes in the crystallographic parameters of Y 0.79- z Al z Yb 0.18 Er 0.03 NbO 4 powders prepared with varying Al content were determined by Rietveld refinement, and their effects on the up- (UC) and down-conversion (DC) spectra were studied. The findings confirmed that the Al 3+ , Yb 3+ , and Er 3+ ions were completely incorporated at the Y 3+ sites. The substitution of the small Al 3+ ions led to the modification of the interatomic distance. As a result, the highest polyhedral distortion index of the YO8 dodecahedron ( D YO ) could be achieved at z = 0.2. Under infrared radiation, UC spectra demonstrated that a two-photon energy transfer (ET) UC process from Yb 3+ to Er 3+ was responsible for the green and red emissions, whose intensities increased dramatically by 160 and 166% at z = 0.2, respectively. This enhancement was a consequence of a large crystal-field asymmetry surrounding the Yb 3+ and Er 3+ ions, which resulted from the highest D YO at z = 0.2. In addition to D , the Yb‒Er interatomic distance was responsible for the enhanced UC emission, affecting the ET probability from Yb 3+ to Er 3+ . Under 379 nm excitation, the DC green emission of Er 3+ also showed the maximal intensity at z = 0.2 owing to the largest D YO . However, a correlation between the crystallographic variations and the DC emissions activated by [NbO 4 ] 3- niobates could not be fully elucidated owing to the complexity of the emission mechanism.

Thermal Annealing and Doping Induced Tailoring of Phase and Upconversion Luminescence of NaYF4:Yb Er Microcrystals

ABSTRACT The influence of Mn2+ ion concentration (x = 0–20 mol%) as well as the role of thermal-annealing temperature (400–600°C) on the structural as well as luminescence properties of NaYF4:Yb, Er (Y: 78-x%, Yb: 20%, Er: 2%) microcrystals prepared via a coprecipitation method is investigated. The cubic phase of the as-prepared NaYF4:Yb, Er (Y: 78%, Yb: 20%, Er: 2%) was found to remain intact upon the addition of the Mn2+ ions, but the thermal-annealing elucidates that the phase of the sample depends upon the annealing temperature as well as the Mn2+ ion concentration. Among the Mn2+ ion co-doped samples, 3 mol% doped samples dominant to have a maximum positive influence on the upconversion luminescence of the sample, and a further increase in concentration leads to the concentration-induced quenching of the upconversion luminescence. Moreover, the enhancement factor of green (), as well as red () emission, depend upon the annealing temperature, with a maximum enhancement factor of 5 and 3.12 times for the sample annealed at 400°C, 8.6 and 7.25 times for the sample annealed at 500°C, and 6 and 4 times for the sample annealed at 600°C, as compared to Mn2+ ion undoped samples. The maximum emission strength for the green as well as red is observed for the sample annealed at 600°C and co-doped with 3 mol Mn2+ ions. The laser power-dependent study on all the samples shows that the upconversion process is a multi-photon process, predominantly a two-photon process.

Radio-frequency evaporation in an optical dipole trap

We present an evaporative cooling technique for atoms trapped in an optical dipole trap that benefits from narrow optical transitions. For an appropriate choice of wavelength and polarization, a single laser beam leads to opposite light shifts in two internal states of the lowest-energy manifold. Radio-frequency coupling between these two states results in evaporative cooling at a constant trap stiffness. The evaporation protocol is well adapted to several atomic species, in particular to the case of Lanthanides such as Er, Dy, and fermionic Yb, but also to alkali-earth metals such as fermionic Sr. We derive the dimensionless expressions that allow us to estimate the evaporation efficiency. As a concrete example, we consider the case of $^{162}\mathrm{Dy}$ and present a numerical analysis of the evaporation in a dipole trap near the ${J}^{\ensuremath{'}}=J$ optical transition at $832\phantom{\rule{0.16em}{0ex}}\mathrm{n}\mathrm{m}$. We show that this technique can lead to runaway evaporation in a minimalist experimental setup.

Interface analysis of SrWO4:Er3+-Yb3+/Si thin films prepared by radio frequency magnetron sputtering for upconversion emission

Upconversion (UC) emission of Er–Yb doped strontium tungstate (SrWO4:Er3+-Yb3+) thin films on silicon substrates prepared by the radio frequency (RF) magnetron sputtering method using different RF powers has been investigated and reported. The X-ray diffraction patterns showed that the tetragonal phase of SrWO4 formed with an improvement in the crystallinity of the films at higher RF power. Atomic force microscopy images demonstrated the homogeneity of the grains on the surface and an increment of grain size with an increase in RF power during deposition. Auger electron spectroscopy was used for the analysis of the interface of the thin films, the Si interdiffusion as well as the role of the thickness with an increase in the sputtering power of the RF deposition. The UC emission of the films prepared at the different RF powers excited at 980 nm was recorded. An enhancement in the intensity with an increase in the RF powers was obtained. Three different bands of UC emission were recorded, which were assigned to the 2H11/2/4S3/2 → 4I15/2 (two green bands) and the one red band (4F9/2 → 4I15/2) transitions for the Er3+ ions. The maximum intensity of UC emission was recorded at 240 W RF power due to a better crystallinity and the bigger size of the grains in the film as well as a better defined interface between the thin film and the substrate.

Synthesis, Spectroscopic Properties and Redox Behavior Kinetics of Rare-Earth Bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato Metal Complexes with Er, Lu and Yb.

Novel bistetrakis-4-[3-(3,4-dicyanophenoxy)phenoxy]phthalocyaninato of complexes erbium, lutetium and ytterbium were synthesized using a template fusion method to prevent any polymerization process. The complexes were separated from the reaction mixtures and characterized by NMR, IR and electron absorption spectroscopy. The spectroscopic properties of the metal phthalocyaninates in chloroform, acetone and tetrahydrofuran were studied. The regular bathochromic shift in the Er–Yb–Lu series was determined. In acetone medium all the complexes obtained were found to exist in an equilibrium state between neutral and reduced forms. The linearity of Lambert-Bouger-Beer curves makes it possible to study the kinetics of redox processes in the presence of phenylhydrazine and bromine. The lutetium complex showed better reducing properties and turned fully into the reduced form, while the erbium and ytterbium ones changed only partially. Upon oxidizing all the phthalocyaninates transformed into a mixture of oxidized and neutral-radical forms. The extinction coefficients and effective redox constants were calculated.