Rui Wang

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Organization: Harbin Institute of Technology

Department: Department of Chemistry

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References

Enhancing upconversion luminescence by annealing processes and the high-temperature sensing of ZnO:Yb/Tm nanoparticles

Co-reporter:Yuemei Li;Yongmei Li;Yanling Xu;Wei Zheng

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 15) pp:7116-7122

Publication Date(Web):2017/07/24

DOI:10.1039/C7NJ01358B

Temperature that affects upconversion luminescence (UCL) is important to biological sensing and magnetic imaging. The temperature-dependent UCL of ZnO:Yb3+/Tm3+ nanoparticles (UCNP) was characterized. A detailed analysis of UCL spectra at different annealing temperatures revealed the effects of annealing temperatures, which were determined by using TGA. The blue and the red UCL emissions under NIR 980 nm excitation were greatly enhanced with the increase of annealing temperature from 300 to 780 °C. The change in high-frequency groups (OH− and CO32−) at different annealing temperatures were investigated using IR technique. It was found that the quenching centers were removed due to an increase of annealing temperature. Moreover, for the temperature range of 293 to 338 K, the thermal sensor based on the position shift of the 475 nm wavelength was studied. In addition, relative sensor sensitivity reached a maximum of 2.1% K−1 at 293 K based on the temperature-dependent fluorescence intensity ratio (FIR) of the 700 and 800 nm upconverted emission, which would make the ZnO:Yb3+/Tm3+ nanoparticles a promising candidate for the biological temperature probe.

White-light upconversion emission of lanthanide double-doped oxide nanoparticles via defect state luminescence of ZnO

Co-reporter:Yuemei Li 李月梅;Yongmei Li 李永梅王锐;Yanling Xu 徐衍岭

Science China Materials 2017 Volume 60( Issue 12) pp:1245-1252

Publication Date(Web):27 November 2017

DOI:10.1007/s40843-017-9110-9

The white upconversion luminescence (UCL) of upconversion nanoparticles (UCNPs) is mainly made up of the color red, green and blue. Interestingly, the white-light-emitting UCNPs can be obtained via a complex method of tridoping lanthanide ions such as Yb3+, Er3+, and Tm3+. We herein report that an excellent white UCL can be obtained from Yb/Tm double-doped ZnO. In this system, the blue and red UCL-emissions around 475 and 652 nm originate from 1G4→3H6 and 1G4→3F4 transition of Tm3+, respectively, and the green one can be attributed to the defect states (oxygen vacancies) luminescence (DSL) of the ZnO host. Meanwhile, the fine nanostructure of ZnO:Yb/Tm is prepared by adjusting the concentration of OH−. Particularly, the one dimentional pencil-shaped nanorods with high aspect ratio achieve a strong green DSL emission due to the high concentration of oxygen vacancy. The oxygen vacancy defects play an irreplaceable role in affecting the intensities of blue and red UCL by acting as the intermediate state in the energy transfer process. More importantly, we demonstrate that the DSL and UCL can be combined into systems, paving a new road for obtaining the white UCL emission.上转换白光由红色、绿色和蓝色组成, 而上转换白光通常是通过复杂的三掺杂稀土离子如Yb3+、 Er3+和Tm3+实现的. 本文报道了一个新型村料, 通过Yb3+、 Tm3+双掺ZnO实现上转换白光输出. 体系获得475nm(1G4→3H6)上转换蓝光和652 nm (1G4→3F4)上转换红光, 上转换绿光发射源于ZnO基质村料缺陷(氧空位)发光. 此外, 通过调节OH−的浓度可以调控纳米村料形貌. 尤其是铅笔状结构纳米棒由于表面具有高浓度的氧空位, 实现了上转换绿光辐射. 同时氧空位缺陷作为能量传递过程的中间态能级, 提高了上转换蓝光以及上转换红光的发光强度.我们的研究首次将缺陷发光机理和上转换发光机理相结合, 为实现上转换白光输出开辟了新道路.

Enhancement of upconversion emission in Er:LiNbO3 by codoping with HfO2 under 1550 nm excitation

Co-reporter:Yannan Qian, Zhengyu Zhang, Xunze Tang, Maxim Ivanov, Haiyan Zhang, Qibai Wu

Optical Materials 2017 Volume 70(Volume 70) pp:

Publication Date(Web):1 August 2017

DOI:10.1016/j.optmat.2017.05.018

•Hf/Er:LiNbO3 crystals are grown to enhance NIR light harvesting.•Converting 1550 nm light into upconversion emission are discussed.•Er3+ cluster sites increase the cross relaxation probability in Hf/Er-8.0/1.0.An increased red upconversion emission produced under excitation at 1550 nm was observed in hafnium and erbium co-doped lithium niobate (Hf (8 mol%)/Er:LiNbO3), which can be used to increase the photovoltaic efficiency of solar cells. Three 1550 nm photons were required to arouse the green and red emissions in Hfx (x = 2, 4, 6 mol%)/Er:LiNbO3, while the red emitting 4F9/2 state was populated by a hybrid two- and three-photon process in Hf(8 mol%)/Er:LiNbO3. The formation of Er3+ cluster sites (ErLi2+-ErNb2−) lead to an efficient cross relaxation process 4I13/2 + 4I13/2 → 4I15/2 + 4I9/2 and enhanced red emission in Hf(8 mol%)/Er:LiNbO3.

Multicolor tunable yellow-red emission in Eu/Er:LiNbO3 under ultraviolet and blue excitation

Co-reporter:Zhengyu Zhang, Xunze Tang, Yannan Qian, Haiyan Zhang, Wenguang Wang, Rui Wang

Optics & Laser Technology 2017 Volume 97(Volume 97) pp:

Publication Date(Web):1 December 2017

DOI:10.1016/j.optlastec.2017.06.010

•Multicolor tunable yellow-red emission are found in Eu/Er:LiNbO3.•Emission spectra under ultraviolet and blue excitation are discussed.•Color coordinates are calculated to reflect the true color of luminescence.The ability to manipulate the multicolor luminescence will greatly enhance the scope of their applications, ranging from infrared solar cells to volumetric multiplexed bioimaging. Tuning from yellow to red emission was successfully achieved in Eu/Er:LiNbO3 under ultraviolet (UV) and blue excitation. The excitation spectra of Eu/Er:LiNbO3 monitored at 590 nm/618 nm/626 nm were studied. The CIE 1931 color coordinates showed that the emissions fell within the yellow and red region, respectively, under 376 nm and 397 nm excitation. The color coordinates shifted from yellow toward red region upon diode laser excitation of 476 nm.

Magnet-induced fabrication of a superhydrophobic surface on ZK60 magnesium alloy

Co-reporter:Zhaozhong Qiu, Jia Sun, Rui Wang, Yushen Zhang, Xiaohong Wu

Surface and Coatings Technology 2016 Volume 286() pp:246-250

Publication Date(Web):25 January 2016

DOI:10.1016/j.surfcoat.2015.12.052

•Superhydrophobic film on PEO coatings with the water contact angle as high as 157°•Superhydrophobic surface was produced under the magnet-induced assembly technology.•Superhydrophobic film increases the corrosion resistances of Mg alloy remarkably.In this work, magnetic Fe3O4 nanoparticles treated with hexadecyltrimethoxysilane were used as immobilization material. Under the anchor of dopamine, the magnetic nanoparticles can be easily deposited on the solid substrate. Array structure was formed by the coated Fe3O4 on the magnesium alloy with the magnet-induced assembly technique. The hierarchical rough surfaces on the substrates form a superhydrophobic coating with a water contact angle as high as 157°. Of note is that the coating significantly decreased the corrosion rate compared with the pristine magnesium alloy in 3.5 wt.% NaCl solution.

Graphene oxide as a corrosion-inhibitive coating on magnesium alloys

Co-reporter:Zhaozhong Qiu, Rui Wang, Jinzhu Wu, Yushen Zhang, Yunfei Qu and Xiaohong Wu

RSC Advances 2015 vol. 5(Issue 55) pp:44149-44159

Publication Date(Web):23 Apr 2015

DOI:10.1039/C5RA05974G

Graphene oxide was formed on the plasma electrolytic oxidation coatings of magnesium alloys via a self-assembly method. The graphene oxide solution was embedded into the porous structures of the coatings to reduce their porosity. The graphene oxide films acted as a physical separation, which inhibited the effects between the protected metal and corrosive media. Furthermore, the film could significantly decrease the corrosion rate compared with pristine magnesium alloy in 3.5 wt% NaCl solution.

Glycerol as a leveler on ZK60 magnesium alloys during plasma electrolytic oxidation

Co-reporter:Zhaozhong Qiu, Yushen Zhang, Yuemei Li, Jinchao Sun, Rui Wang and Xiaohong Wu

RSC Advances 2015 vol. 5(Issue 78) pp:63738-63744

Publication Date(Web):21 Jul 2015

DOI:10.1039/C5RA08953K

Glycerol (C3H8O3), an organic waste generated by the biodiesel industry, has recently been proposed as a valuable green additive. The influence of glycerol on the morphology, composition and corrosion resistance of ZK60 magnesium alloys during the plasma electrolytic oxidation process has been investigated. The adsorption behavior of C3H8O3 molecules on Mg (002) surface has been studied by using molecular dynamics simulations. Results predict that C3H8O3 could be used as a promising leveler during the plasma electrolytic oxidation process. The silicate electrolyte with glycerol could increase the unit-area adsorptive capacity of the negative ions at the anode–electrolyte interface, and thus improves the smoothness and corrosion resistance of the coating.

Study of Coating Growth Behavior During the Plasma Electrolytic Oxidation of Magnesium Alloy ZK60

Co-reporter:Zhaozhong Qiu;Yushen Zhang

Journal of Materials Engineering and Performance 2015 Volume 24( Issue 4) pp:1483-1491

Publication Date(Web):2015 April

DOI:10.1007/s11665-015-1422-4

Plasma electrolytic oxidation technique was used to coat ZK60 magnesium alloy in a silicate-based electrolyte. Effects of oxidation time on the morphology, phase structure, and corrosion resistance of the resulting coatings were systematically investigated by scanning electron microscopy, energy-dispersive spectrometry, x-ray diffraction, x-ray photoelectron spectroscopy, and potentiodynamic polarization. The main components of the inner and the outer coating layers were MgO and Mg2SiO4, respectively. It was also found that the oxidation time has a significant impact on the corrosion resistance properties of the coatings. The coating obtained within the oxidation time of 360 s exhibited a corrosion current of 7.6 × 10−8 A/cm2 in 3.5 wt.% NaCl solution, which decreased significantly when comparing with the pristine magnesium alloy.

Effect of crystallinity on the optical thermometry sensitivity of Tm3+/Yb3+ codoped LiNbO3 crystal

Co-reporter:Lili Xing, Weiqi Yang, Decai Ma, Rui Wang

Sensors and Actuators B: Chemical 2015 Volume 221() pp:458-462

Publication Date(Web):31 December 2015

DOI:10.1016/j.snb.2015.06.132

•The 3F2,3 and 3H4 levels of Tm3+ in LiNbO3 crystal are thermally coupled levels.•Crystallinity of sensing material greatly affects the optical thermometry sensitivity.•Higher crystallinity of host material is beneficial to improve sensitivity and resolution.•Single crystal materials are more suitable to high temperature applications.Under 980 nm excitation, optical temperature sensing properties based on the upconversion emissions of Tm3+ in LiNbO3 polycrystal and single crystal are studied in the temperature range of 323–773 K. It is observed the 3F2,3 and 3H4 levels of Tm3+ are thermally coupled levels in both LiNbO3 polycrystal and single crystal, suggesting that the Tm3+-doped LiNbO3 crystals possess potential application in optical thermometry. Moreover, the crystallinity of host material greatly affects the optical thermometry sensitivity. The splitting degrees of upconversion emission spectra are changed with the crystallinities of LiNbO3 crystals, smaller splitting degree can result in higher absolute sensitivity. By optimizing the Tm3+ and Yb3+ ion concentrations, LiNbO3 single crystal is promising for optical high temperature sensor. These results reveal that the higher crystallinity of sensing material is beneficial to improve the sensitivity and resolution of optical temperature sensor.

Upconversion for enlarging solar spectrum response in near-stoichiometric and congruent Er:LiNbO3 crystals

Co-reporter:Yannan Qian, Biao Wang, Rui Wang, Senpei Gao, Yingying Niu

Optical Materials 2014 Volume 36(Issue 5) pp:941-944

Publication Date(Web):March 2014

DOI:10.1016/j.optmat.2013.12.041

•An enhancement of green upconversion emission is observed in Er:NSLN.•The Er3+ cluster sites (ErLi2+–ErNb2-) are dissociated in Er:NSLN crystal.•Enhanced green emission arises from the inefficient cross relaxation process.•Er:NSLN will be considered as an upconverter to improve solar spectrum response.To increase the photovoltaic efficiency of solar cell, the visible luminescence produced at the excitation of the near infrared laser light in near-stoichiometric and congruent LiNbO3 crystals heavily doped with Er3+ ions (Er:NSLN and Er:CLN, respectively) were investigated. An enhancement of the green upconversion emission observed in Er:NSLN crystal was attributed to the inefficient cross relaxation processes of 2H11/2 + 4I13/2 → 4I11/2 + 4F9/2 and 4F7/2 + 4I11/2 → 4F9/2 + 4F9/2. The Er content in the crystal was measured by an inductively coupled plasma mass spectrometry (ICP-MS). The OH− absorption and UV–vis-near infrared absorption spectra indicated that the Er3+ cluster sites (ErLi2+–ErNb2-) were dissociated in Er:NSLN crystal. The strong green upconversion emission produced by Er:NSLN crystal will be beneficial for improving the practical performance of solar cells.Graphical abstract

Upconversion emission in near-stoichiometric LiNbO3:Er3+ crystal

Co-reporter:Yannan Qian, Biao Wang, Rui Wang, Lili Xing and Yanling Xu

RSC Advances 2013 vol. 3(Issue 32) pp:13507-13514

Publication Date(Web):21 May 2013

DOI:10.1039/C3RA40744F

Important for increasing the efficiency of solar cells, multifunctional near- stoichiometric LiNbO3 doped with Er3+ ions (Er:NSLN) could be considered as a luminescent layer to improve the solar spectrum response. The upconversion emission spectra show that Er:NSLN crystal converts the near infrared wavelength light which cannot be absorbed by the solar cells into the visible upconversion luminescence. The increased green and red upconversion emissions are observed in Er:NSLN crystal, and both green and red emitting states are populated by the three-photon process at the low pump power. As for the high pump power, the one-photon process is attributed to the “saturation” of the upconversion process. The Judd–Ofelt intensity parameters of Er:NSLN are calculated to be Ω2 = 9.17 × 10−20 cm2, Ω4 = 2.47 × 10−20 cm2 and Ω6 = 1.00 × 10−20 cm2. Based on McCumber theory, the enhanced emission and absorption cross-sections of the green and red emissions indicate that Er:NSLN used as the upconversion luminescent layer could emit high efficiency of visible luminescence re-absorbed by the solar cells.

Defect structures and optical characteristics of Er3+ ion in Er:LiNbO3 crystals

Co-reporter:Yannan Qian, Rui Wang, Biao Wang, Chao Xu, Lili Xing, Yanling Xu

Journal of Molecular Structure 2013 Volume 1035() pp:101-108

Publication Date(Web):13 March 2013

DOI:10.1016/j.molstruc.2012.09.039

Congruent Er:LiNbO3 crystals were grown by Czochraski method. The OH− absorption and UV–vis-near infrared absorption spectra indicated that Er3+ cluster sites were formed in LiNbO3 crystal doped with 3 mol% Er3+ ions. Studies on the stokes and anti-stokes spectra showed that the formation of Er3+ cluster sites could increase the rate of cross relaxation processes. Judd–Ofelt theory was carried out to discuss the spectral characteristics of Er3+ ions in Er:LiNbO3 crystals. Based on Füchtbauer–Ladenburg and McCumber theory, the emission cross section of the 4I13/2 → 4I15/2 transition of Er3+ ion was calculated, and the potential laser performance was evaluated by the gain cross section spectra. Er:LiNbO3 crystal codoped with Zn2+ ions was also grown to discuss the relation between the defect structure and optical characteristics of Er3+ ion.Highlights► OH− and UV–vis-near infrared absorption spectra of Er:LiNbO3 crystals. ► Stokes and anti-stokes luminescence spectra of Er:LiNbO3 and Zn/Er:LiNbO3. ► Relation between structural and optical characteristics of Er:LiNbO3 crystals. ► Near infrared emission spectra of Er:LiNbO3 crystals under 980 nm excitation. ► J–O parameters, absorption and emission cross section spectra are discussed.

Controllable and white upconversion luminescence in LiNbO3:Ln3+ (Ln = Ho, Yb, Tm) single crystals

Co-reporter:Lili Xing, Yanling Xu, Rui Wang, Wei Xu, Shuo Gu, Xiaohong Wu

Chemical Physics Letters 2013 Volume 577() pp:53-57

Publication Date(Web):9 July 2013

DOI:10.1016/j.cplett.2013.05.050

•Controllable and white upconversion emissions are obtained.•Ideal white-light emissions can be obtained with pump power from 100 mW to 900 mW.•Energy transfer process of RE ions and pump power result in the color variation.•Great inspirations are given in realizing the target color of interest.Ho3+, Yb3+ and Tm3+ tri-doped LiNbO3 single crystals with various dopant concentrations were prepared by Czochralski method. Controllable and white upconversion emissions are generated under 980 nm excitation at room temperature. The variations of upconversion spectra and CIE coordinates with dopant concentrations and pump powers are studied in details on the basis of energy transfer processes. Ideal white-light emissions can be obtained even though the pump power is varied from 100 to 900 mW. Based on the present experiments, great inspirations are given in realizing the target color of interest by varying dopant concentrations and pump powers.

*Ir4+ ion-free 12CaO7Al2O3 single crystal grown by the CZ method

Co-reporter:Jinchao Sun;Yanling Xu;Xinrong Liu ;Yunfei Qu

Crystal Research and Technology 2013 Volume 48( Issue 8) pp:505-510

Publication Date(Web):

DOI:10.1002/crat.201300080

Ir⁴⁺ ion-free 12CaO•7Al₂O₃ (C12A7) single crystals that were colorless and transparent have been grown by the CZ method under 0.5% oxygen-containing nitrogen atmospheres for the first time. Powder X-ray diffraction patterns and X-ray single-crystal diffraction were used to investigate the microstructure and quality of the C12A7 single crystal. The results show that the crystal was a C12A7 single crystal with tetragonal symmetry. The content of Ir⁴⁺ in the C12A7 single crystal was tested by ICP along with visible-light transmittance. There was no Ir⁴⁺ in the C12A7 crystal grown in a 0.5% oxygen-containing nitrogen atmosphere. Contents of Ir⁴⁺ in C12A7 crystal grown under 1% and 2% oxygen-containing nitrogen atmospheres were 500 ppm and 400 ppm, respectively. The microstructure of C12A7 single crystal was determined by the content of oxygen in the growth process: the occurrence of bubbles and color increase when the content of oxygen is increased. Bubbles and color decrease when the oxygen content is lowered, bubbles disappeared and the color of C12A7 turns into transparent when the content of oxygen is 0.5%, the C12A7 phase decomposed when the content of oxygen was lower than 0.5%. So, the content of oxygen was responsible for the bubbles, color and cracking, and these also can be limited by controlling the content of oxygen.

Preparation and upconversion luminescence characterization of 12CaO7Al2O3:Ho3+/Yb3+ polycrystals

Co-reporter:Yunfei Qu;Liang Liu;Jinchao Sun;Lili Xing;Ye Tao ;Xiaohong Wu

Crystal Research and Technology 2013 Volume 48( Issue 12) pp:1031-1038

Publication Date(Web):

DOI:10.1002/crat.201300112

The effect of Yb³⁺ concentration on the fluorescence of 12CaO·7 Al₂O₃:Ho³⁺/Yb³⁺ polycrystals is investigated. The Raman spectra of pure C12A7 under 633-nm excitation show that the highest photon energy is 787.267 cm⁻¹, which is not much bigger than general fluorides, so it can realize high efficiency upconversion. The upconversion emission spectra suggest that the green upconversion emission centered at 548 nm and the red upconversion emission at 662 nm correspond to the ⁵F₄/⁵S₂⁵I₈ and ⁵F₅⁵I₈ transition of Ho³⁺ ions, respectively. The intensity of the upconversion luminescence and the ratio of red to green are changed with Yb³⁺ ion concentration. The pump dependence and luminescence decay dynamics spectra show the green and red upconversion emissions are populated by a two-photon process, and the upconversion mechanisms are analyzed. The relative luminous efficiencies of green and red emissions are 2.035% and 0.7%, respectively. The normalized efficiency obtained for green emission of Ho³⁺ at RT when the sample is excited by 980-nm light with an absorbed intensity of 7.5 W/cm² is 0.27 cm²/W. This result is comparable to the values obtained in YF₃ for the Yb³⁺, Er³⁺ green emission. The C12A7 with upconversion red and green light will be a promising luminous material.

Optical spectroscopy and laser parameters of Zn2+/Er3+/Yb3+-tridoped LiNbO3 crystal

Co-reporter:Yannan Qian, Rui Wang, Chao Xu, Xiaohong Wu, Lili Xing, Yanling Xu

Journal of Luminescence 2012 Volume 132(Issue 8) pp:1976-1981

Publication Date(Web):August 2012

DOI:10.1016/j.jlumin.2012.03.014

The Zn/Er/Yb:LiNbO3 and Er/Yb:LiNbO3 crystals were grown by the Czochralski technique. The laser characteristics of 1.54 μm emission were predicted based on the Judd–Ofelt theory, and the intensity parameters Ωt (Ω2=7.23×10−20 cm2, Ω4=3.15×10−20 cm2 and Ω6=1.43×10−20 cm2) were obtained. The stimulated emission cross sections (σem) at 1.54 μm emission in Zn/Er/Yb:LiNbO3 were calculated based on the McCumber theory and the Füchtbauer–Ladenburg theory. The gain cross section spectrum of Zn/Er/Yb:LiNbO3 crystal was also investigated. Under 980 nm excitation, a lenghthening lifetime of 1.54 μm emission and an enhancement of green upconversion emission were observed for Zn/Er/Yb:LiNbO3 crystal. The studies on the power pump dependence and the upconversion mechanism suggested that both green and red upconversion emissions were populated via the three-photon process, and Zn2+ ion tridoping increases the probability of cross relaxation process between the two neighboring Er3+ ions.Graphical AbstractHighlights► Zn/Er/Yb:LiNbO3 crystal was grown by the Czochralski technique. ► Intensity parameters Ωt are calculated based on the Judd–Ofelt theory. ► Emission cross sections at 1.54 μm are obtained by F–L and M-C. ► Gain cross section spectrum of Zn/Er/Yb:LiNbO3 is investigated. ► Upconversion emission characteristics of Er3+ ion are measured.

Upconversion white-light emission in Ho3+/Yb3+/Tm3+ codoped LiNbO3 polycrystals

Co-reporter:Lili Xing, Rui Wang, Wei Xu, Yannan Qian, Yanling Xu, Chunhui Yang, Xinrong Liu

Journal of Luminescence 2012 Volume 132(Issue 6) pp:1568-1574

Publication Date(Web):June 2012

DOI:10.1016/j.jlumin.2012.01.053

Ho3+/Yb3+/Tm3+ codoped LiNbO3 polycrystals exhibiting upconversion white-light under 980 nm excitation have been successfully fabricated by the high temperature solid-state reaction method. CIE coordinate of the Ho3+/Yb3+/Tm3+/LiNbO3 polycrystal is (0.34, 0.35), which is very close to the standard equal energy white-light illuminate (0.33, 0.33). Efficient green, red, and blue upconversion emissions have been observed. The luminescent decay dynamics are studied, and rate equations for the blue, green, and red emissions are set up to analyze the upconversion luminescence mechanism. The present results demonstrate that the competition between the linear decay and the upconversion process for the depletion of the intermediate excited states plays an important role in upconversion mechanism. The LiNbO3 with upconversion white-light will be a promising luminous material.Highlights► CIE coordinate of the Ho3+/Yb3+/Tm3+/LiNbO3 is (0.34, 0.35). ► Efficient red, green, and blue emissions are observed. ► Competition (Linear and UC) involved in upconversion process. ► The ET from Tm3+ to Ho3+ is observed.

Spectroscopic characteristics of 1.54 μm emission in Er/Yb:LiNbO3 crystals tridoped with In3+ ions

Co-reporter:Yannan Qian, Rui Wang, Chao Xu, Wei Xu, Xiaohong Wu, Chunhui Yang

Journal of Alloys and Compounds 2012 Volume 527() pp:152-156

Publication Date(Web):25 June 2012

DOI:10.1016/j.jallcom.2012.02.160

A series of Er/Yb:LiNbO3 crystals tridoped with x mol% In3+ ions (x = 1, 2 and 3 mol%) was grown by Czochralski technique. Under 980 nm excitation, the strongest intensity of 1.54 μm emission was observed for 2 mol% In3+-tridoped Er/Yb:LiNbO3 crystal. The UV–vis–infrared absorption spectra of In/Er/Yb:LiNbO3 crystals were measured, and Judd–Ofelt (J–O) theory was carried out to predict the J–O intensity parameters (Ωt), radiative lifetime τrad and fluorescence branching ratio β. The emission cross-section of the 4I13/2 → 4I15/2 transition of Er3+ ion was calculated by Füchtbauer–Ladenburg (F-L) method. The gain cross-section, estimated as a function of the population inversion ratio, allowed us to evaluate a potential laser performance of In/Er/Yb:LiNbO3 crystal at 1.54 μm emission. The fluorescence lifetimes of the 4I13/2 → 4I15/2 transition in In/Er/Yb:LiNbO3 crystals were measured.Graphical abstractHighlights► Zr/Er/Yb:LiNbO3 crystals were grown by Czochralski technique. ► The strongest 1.54 μm emission is observed for In (2 mol%)-doped Er/Yb:LiNbO3. ► Judd–Ofelt parameters based on UV–vis–infrared absorption spectra are discussed. ► Absorption/emission cross-section and fluorescence lifetimes are reported. ► Gain cross-section spectra in the eye-safe regime of 1450–1650 nm are studied.

The effect of In3+ ion on the optical characteristics of Er3+ in Er/Yb:LiNbO3 crystal

Co-reporter:Yannan Qian, Rui Wang, Lili Xing, Yanling Xu, Chunhui Yang, Xinrong Liu

Optical Materials 2012 Volume 34(Issue 5) pp:884-888

Publication Date(Web):March 2012

DOI:10.1016/j.optmat.2011.11.028

The effect of In3+ ion on the optical characteristics of Er3+ ion in Er/Yb:LiNbO3 crystal under 980 nm excitation has been investigated. The Er and Yb contents in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES). A significant enhancement of 1.54 μm emission was observed for Er/Yb:LiNbO3 crystal doped with 1 mol% In2O3. The studies on the UV–vis absorption and the OH− absorption spectra indicate that the threshold concentration of In3+ ion decreases with the Er/Yb doping in Er/Yb/In:LiNbO3 crystal. The 1 mol% In2O3 doping results in the reduction of absorption cross section in the UV–vis region, meaning the formation of Er3+ cluster sites. The enhancement of 1.54 μm emission is attributed to the larger probabilities of the cross relaxation processes 4S3/2 + 4I15/2 → 4I9/2 + 4I13/2 (Er), 4S3/2 + 4I15/2 → 4I13/2 + 4I9/2 (Er) and 4I9/2 + 4I15/2 → 4I13/2 + 4I13/2 (Er) induced by Er3+ cluster sites.Graphical abstractHighlights► In3+ threshold concentration decreases in Er/Yb/In:LiNbO3 crystal. ► The Er and Yb contents in the crystals are measured by ICP-AES. ► An enhancement of 1.54 μm emission is observed for In/Er/Yb:LiNbO3 crystal. ► Er3+ cluster sites are formed in Er/Yb:LiNbO3 with 2 mol% In3+ ions.

Dopant occupancy and optical properties of Er3+ in Er/Zn-codoped lithium niobate crystal

Co-reporter:Yannan Qian, Rui Wang, Lili Xing, Yanling Xu, Chunhui Yang

Optics Communications 2012 Volume 285(13–14) pp:2986-2989

Publication Date(Web):15 June 2012

DOI:10.1016/j.optcom.2012.02.066

The effect of Zn2+ ion on the dopant occupancy and optical characteristic of Er3+ ion in Er/Zn-codoped LiNbO3 crystal is reported. The intense 1.54 μm and relatively weak green upconversion emissions are observed for Er (1 mol%)/Zn (6 mol%):LiNbO3 crystal. The OH− absorption and the time-resolved spectra show that the Zn2+ codoping decreases the threshold concentration of Er3+ ion in Er/Zn-codoped LiNbO3 crystal. The experimental results here imply that the potential application of Er3+-doped LiNbO3 crystal can be designed and optimized on the basis of the theoretical investigations.Highlights► The intense 1.54 μm emission is observed for Er (1 mol%)/Zn (6 mol%):LiNbO3 crystal. ► The Zn codoping decreases the threshold concentration of Er3+ ion in Zn/Er:LiNbO3. ► The Zn codoping leads to the redistribution of the Er3+ ions. ► The experimental results are consistent with the theoretical investigations.

Blue upconversion luminescence in 12 CaO·7 Al2O3:Tm3 +/Yb3 + polycrystals

Co-reporter:Rui Wang, Liang Liu, Jinchao Sun, Yannan Qian, Yushen Zhang, Yanling Xu

Optics Communications 2012 Volume 285(Issue 6) pp:957-959

Publication Date(Web):15 March 2012

DOI:10.1016/j.optcom.2011.11.062

The effect of Yb3 + concentration on the fluorescence of 12 CaO·7 Al2O3:Tm3 +/Yb3 + polycrystals is investigated. Under the excitation of 980 nm laser, the strong blue (477 nm) emission band is observed and attributed to 1G4 → 3H6 of Tm3 +. The ratio of blue to red emission increases with the increasing of Yb3 + and remains constant at 10 mol% Yb3 +. The pump dependence and upconversion mechanisms show that the two-photon cooperative upconversion process is responsible for the enhancement of the blue upconversion emission. The Commission Internationale de l'eclairage chromaticity coordinates (x, y) illustrate that the 12 CaO·7 Al2O3:1 mol% Tm3 +/10 mol% Yb3 + can emit high-purity blue light.

The influence of Zn2+ ion on the 1.5 μm laser properties of LiNbO3 crystal heavily doped with Er3+ ion

Co-reporter:Yannan Qian, Rui Wang, Chao Xu, Wei Xu, Xiaohong Wu, Lili Xing, Yanling Xu

Optics & Laser Technology 2012 Volume 44(Issue 7) pp:2297-2301

Publication Date(Web):October 2012

DOI:10.1016/j.optlastec.2012.02.017

The spectral characteristics of 1.54 μm emission in a series of Zn/Er:LiNbO3 crystals with heavy Er content and variable Zn content were reported. The inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentration of Er3+ ion in the crystal. The absorption and emission spectra of Zn/Er:LiNbO3 crystals were measured. Based on Judd–Ofelt theory, the spectral parameters such as intensity parameters Ωt (t=2, 4 and 6), transition strengths, radiative transition probabilities, radiative lifetime and fluorescence branching ratio have been obtained in Zn/Er:LiNbO3 system. The emission cross section corresponding to 4I13/2→4I15/2 transition of Er3+ ion was obtained according to Füchtbauer–Ladenburg theory. The gain cross section of Er:LiNbO3 crystal codoped with 6 mol% Zn2+ ions were also discussed in this work.Highlights► Zn/Er:LiNbO3 crystals are grown by Czochralski technique. ► Laser performance of 1.54 μm is predicted based on Judd–Ofelt theory. ► Füchtbauer–Ladenburg is used to calculate emission cross sections at 1.54 μm. ► The gain cross section spectra of Zn/Er:LiNbO3 crystal are discussed.

Influence of Zn2+ ions concentration on the optical properties of Zn/Er:LiNbO3 crystals

Co-reporter:Yannan Qian;Lili Xing;Yanling Xu;Chunhui Yang ;Xinrong Liu

Crystal Research and Technology 2011 Volume 46( Issue 11) pp:1137-1142

Publication Date(Web):

DOI:10.1002/crat.201100254

Abstract

Congruent Er³⁺(3 mol%):LiNbO₃ crystals codoped with ZnO (X mol %, X=0, 3, 6 and 7) were grown by the Czochralski technique. The Er contents in the crystals were measured by an inductively coupled plasma atomic emission spectrometer (ICP-AES). Under 800 nm excitation, the upconversion emission spectra reveal an enhancement of the green emission with respect to the red emission when the Zn²⁺ ions are introduced into Er:LiNbO₃ crystal. The effect of Zn²⁺ ions concentration on the intensity ratio of the green to red emission has been investigated. Two cross-relaxation processes (²H_11/2 + ⁴I_13/2 ⁴I_11/2 + ⁴F_9/2 and ⁴F_7/2 + ⁴I_11/2 ⁴F_9/2 + ⁴F_9/2) are involved in populating the ⁴F_9/2 state, which bypass the green-emitting states. The OH^- absorption spectra indicate that the Zn²⁺ codoping leads to a decreased concentration of Er³⁺ cluster sites contributing to the enhancement of the green emission. The studies on UV-vis absorption spectra show that the heavily codoped with Zn²⁺ results in the reformation of the Er³⁺ cluster sites in Er:LiNbO₃. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)