10 W single-mode Er/Yb co-doped all-fiber amplifier with suppressed Yb-ASE

NASA Astrophysics Data System (ADS)

Sobon, G.; Sliwinska, D.; Abramski, K. M.; Kaczmarek, P.

2014-02-01

In this work we demonstrate a single-frequency, single-mode all-fiber master oscillator power amplifier (MOPA) source, based on erbium-ytterbium co-doped double-clad fiber emitting 10 W of continuous wave power at 1565 nm. In the power amplifier stage, the amplified spontaneous emission from Yb3+ ions (Yb-ASE) is forced to recirculate in a loop resonator in order to provide stable lasing at 1060 nm. The generated signal acts as an additional pump source for the amplifier and is reabsorbed by the Yb3+ ions in the active fiber, allowing an increase in the efficiency and boosting the output power. The feedback loop also protects the amplifier from parasitic lasing or self-pulsing at a wavelength of 1 μm. This allows one to significantly scale the output power in comparison to a conventional setup without any Yb-ASE control.

Gain and noise figure enhancement of Er+3/Yb+3 co-doped fiber/Raman hybrid amplifier

NASA Astrophysics Data System (ADS)

Mahran, O.

2016-02-01

An Er/Yb co-doped fiber/Raman hybrid amplifier (HA) is proposed and studied theoretically and analytically to improve the gain and noise figure of optical amplifiers. The calculations are performed under a uniform dopant and steady-state conditions. The initial energy transfer efficiency for Er/Yb co-doped fiber amplifier (EYDFA) is introduced, while the amplified spontaneous emission (ASE) is neglected. The glass fiber used for both Er/Yb and Raman amplifiers is phosphate. Different pump powers are used for both EYDFA and RA with 1 μW input signal power, 1 m length of Er/Yb amplifier and 25 km length of Raman amplifier (RA). The proposed model is validated for Er/Yb co-doped amplifier and Raman amplifier separately by comparing the calculating results with the experimental data. A high gain and low noise figure at 200 mW Raman pump power and 500 mW Er/Yb pump power are obtained for the proposed HA as compared with the experimental results of EYDFA, Raman amplifier and the EDFA/Raman hybrid amplifier.

Investigation of ASE and SRS effects on 1018nm short-wavelength Yb3+-doped fiber laser

NASA Astrophysics Data System (ADS)

Xie, Zhaoxin; Shi, Wei; Sheng, Quan; Fu, Shijie; Fang, Qiang; Zhang, Haiwei; Bai, Xiaolei; Shi, Guannan; Yao, Jianquan

2017-03-01

1018nm short wavelength Yb3+-doped fiber laser can be widely used for tandem-pumped fiber laser system in 1 μm regime because of its high brightness and low quantum defect (QD). In order to achieve 1018nm short wavelength Yb3+-doped fiber laser with high output power, a steady-state rate equations considering the amplified spontaneous emission (ASE) and Stimulated Raman Scattering (SRS) has been established. We theoretically analyzed the ASE and SRS effects in 1018nm short wavelength Yb3+-doped fiber laser and the simulation results show that the ASE is the main restriction rather than SRS for high power 1018nm short wavelength Yb3+-doped fiber laser, besides the high temperature of fiber is also the restriction for high output power. We use numerical solution of steady-state rate equations to discuss how to suppress ASE in 1018nm short wavelength fiber laser and how to achieve high power 1018nm short-wavelength fiber laser.

Synthesis and characterization of Nd3+: Yb3+ co-doped near infrared sensitive fluorapatite nanoparticles as a bioimaging probe

NASA Astrophysics Data System (ADS)

Karthi, S.; Kumar, G. A.; Sardar, D. K.; Santhosh, C.; Girija, E. K.

2018-03-01

Trivalent Nd and Yb co-doped rod shaped hexagonal phase fluorapatite (FAP) nanoparticles of length and width about 32 and 13 nm, respectively were prepared by hydrothermal method and investigated the ability for 980 nm emission via Nd3+ → Yb3+ energy transfer with the objective of utilizing them in biomedical imaging. Nd3+ → Yb3+ energy transfer in FAP was studied as a function of both Nd3+ and Yb3+ concentrations and found that when Yb3+ concentration was 10 mol% the FAP phase has partially turned in to YbPO4 phase. The Yb3+ emission intensity at 980 nm significantly increased up to 5 mol% Yb3+ doping and then reduced drastically for further increase in its concentration. Nd3+ →Yb3+ energy transfer rates were evaluated from the decay curves and found that a transfer rate of 71% for 2 mol% Nd3+ co-doped with 5 mol% Yb3+. The cytocompatibility test with fibroblast like cells using MTT assay revealed that the nanoparticles are compatible with the cells.

Thermoluminescence properties of Yb-Tb-doped SiO2 optical fiber subject to 6 and 10 MV photon irradiation

NASA Astrophysics Data System (ADS)

Sahini, M. H.; Wagiran, H.; Hossain, I.; Saeed, M. A.; Ali, H.

2014-08-01

This paper reports thermoluminescence characteristics of thermoluminescence dosimetry 100 chips and Yb-Tb-doped optical fibers irradiated with 6 and 10 MV photons. Thermoluminescence response of both dosimeters increases over a wide photon dose range from 0.5 to 4 Gy. Yb-Tb-doped optical fibers demonstrate useful thermoluminescence properties and represent a good candidate for thermoluminescence dosimetry application with ionizing radiation. The results of this fiber have been compared with those of commercially available standard thermoluminescence dosimetry-100 media. Commercially available Yb-Tb-doped optical fibers and said standard media are found to yield a linear relationship between dose- and thermoluminescence signal, although Yb-Tb-doped optical fibers provide only 10 % of the sensitivity of thermoluminescence dosimetry-100. With better thermoluminescence characteristics such as small size (125 μm diameter), high flexibility, easy of handling and low cost, as compared to other thermoluminescence materials, indicate that commercial Yb-Tb-doped optical fiber is a promising thermoluminescence material for variety of applications.

Characterizations of Pr-doped Yb3Al5O12 single crystals for scintillator applications

NASA Astrophysics Data System (ADS)

Yoshida, Yasuki; Shinozaki, Kenji; Igashira, Takuya; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-04-01

Yb3Al5O12 (YbAG) single crystals doped with different concentrations of Pr were synthesized by the Floating Zone (FZ) method. Then, we evaluated their basic optical and scintillation properties. All the samples showed photoluminescence (PL) with two emission bands appeared approximately 300-500 nm and 550-600 nm due to the charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. A PL decay profile of each sample was approximated by a sum of two exponential decay functions, and the obtained decay times were 1 ns and 3-4 ns. In the scintillation spectra, we observed emission peaks in the ranges from 300 to 400 nm and from 450 to 550 nm for all the samples. The origins of these emissions were attributed to charge transfer luminescence of Yb3+ and intrinsic luminescence of the garnet structure, respectively. The scintillation decay times became longer with increasing the Pr concentrations. Among the present samples, the 0.1% Pr-doped sample showed the lowest scintillation afterglow level. In addition, pulse height spectrum of 5.5 MeV α-rays was demonstrated using the Pr-doped YbAG, and we confirmed that all the samples showed a full energy deposited peak. Above all, the 0.1% Pr-doped sample showed the highest light yield with a value of 14 ph/MeV under α-rays excitation.

Color tunable emission through energy transfer from Yb3+ co-doped SrSnO3: Ho3+ perovskite nano-phosphor

NASA Astrophysics Data System (ADS)

Jain, Neha; Singh, Rajan Kr.; Sinha, Shriya; Singh, R. A.; Singh, Jai

2018-04-01

First time color tunable lighting observed from Ho3+ and Yb3+ co-doped SrSnO3 perovskite. Down-conversion and up-conversion (UC) photoluminescence emission spectra were recorded to understand the whole mechanism of energy migration between Ho3+ and Yb3+ ions. The intensity of green and red emission varies with Yb3+ doping which causes multicolour emissions from nano-phosphor. The intensity of UC red emission (654 nm) obtained from 1 at.% Ho3+ and 3 at.% Yb3+ co-doped nano-phosphor is nine times higher than from 1 at.% Ho3+ doped SrSnO3 nano-phosphor. Enhanced brightness of 654 nm in UC process belongs in biological transparency window so that it might be a promising phosphor in the bio-medical field. Moreover, for the other Yb3+ co-doped nano-phosphor, Commission Internationale de l'Éclairage chromaticity co-ordinates were found near the white region and their CCT values lie in the range 4900-5100 K indicating cool white. Decay time was measured for 545 nm emission of Ho3+ ion found in 7.652 and 8.734 µs at 355 nm excitation. The variation in lifetime was observed in ascending order with increasing Yb3+ concentration which supports PL emission spectra observation that with increasing Yb3+ concentration, rate of transition has changed. These studies reveal that Ho3+ and Yb3+ co-doped phosphor is useful for fabrication of white LEDs.

Ultralow-threshold laser and blue shift cooperative luminescence in a Yb{sup 3+} doped silica microsphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yantang, E-mail: g@fzu.edu.cn; Huang, Yu; Zhang, Peijin

2014-02-15

An experimental investigation on ultralow threshold laser and blue shift cooperative luminescence (CL) in a Yb{sup 3+} doped silica microsphere (YDSM) with continuous-wave 976 nm laser diode pumping is reported. The experimental results show that the YDSM emits laser oscillation with ultralow threshold of 2.62 μW, and the laser spectrum is modulated by the microsphere morphology characteristics. In addition, blue emission of YDSM is also observed with the increase of pump power, which is supposed to be generated by CL of excited Yb ion-pairs with the absorption of 976 nm photons and Si-O vibration phonons, and the process is explainedmore » with an energy level diagram. This property of the blue shift CL with phonons absorption in the Yb{sup 3+}doped microcavity makes it attractive for the application of laser cooling based on anti-Stokes fluorescence emission, if the Yb{sup 3+}doped microcavity made from with low phonon energy host materials.« less

Transparent layered YAG ceramics with structured Yb doping produced via tape casting

NASA Astrophysics Data System (ADS)

Hostaša, Jan; Piancastelli, Andreana; Toci, Guido; Vannini, Matteo; Biasini, Valentina

2017-03-01

The flexibility of the ceramic production process, in particular in terms of shaping and spatial control of distribution of active ions, is one of the strong points in favor of transparent ceramics. In high power lasers in particular, where thermal management is a critical issue, the finely controlled design of spatial distribution of the doping ions within the laser gain media can reduce undesired thermally induced effects and large temperature gradients, and thus enhance the efficiency and laser beam quality especially under increased thermal load. In the present work transparent structured YAG ceramics with Yb doping were produced by tape casting followed by thermal compression of assembled tapes and sintered under high vacuum. The thermal compression of variously doped tape cast layers is a very promising method because it allows a high precision and good control over dopant distribution in the sintered material. After sintering, the distribution of Yb across the layers was characterized by SEM-EDX and the thickness of Yb diffusion zones between the layers with different Yb content was measured. Optical homogeneity was assessed by means of optical transmittance mapping of the samples and by 2D scanning of laser output. The effect of structured dopant distribution on laser performance was measured in quasi-CW and CW regime with different duty factors. Slope efficiency values higher than 50% were measured both in quasi-CW and in CW lasing conditions. The results are in good agreement with previously calculated predictions, confirming the beneficial effect of structured doping on laser performances and enlightening the impact of the residual scattering losses. Compared to other processing methods, such as the pressing of granulated powders, tape casting followed by thermal compression leads to straight and narrow interfaces between layers with different composition and allows to build structures composed of extremely thin layers with defined dopant content.

Upconversion improvement in KLaF4:Yb3+/Er3+ nanoparticles by doping Al3+ ions

NASA Astrophysics Data System (ADS)

Zhou, Haifang; Wang, Xiechun; Lai, Yunfeng; Cheng, Shuying; Zheng, Qiao; Yu, Jinlin

2017-10-01

Rare-earth ion-doped upconversion (UC) materials show great potential applications in optical and optoelectronic devices due to their novel optical properties. In this work, hexagonal KLaF4:Yb3+/Er3+ nanoparticles (NPs) were successfully synthesized by a hydrothermal method, and remarkably enhanced upconversion luminescence in green and red emission bands in KLaF4:Yb3+/Er3+ NPs has been achieved by doping Al3+ ions under 980 nm excitation. Compared to the aluminum-free KLaF4:Yb3+/Er3+ NPs sample, the UC fluorescence intensities of the green and red emissions of NPs doped with 10 at.% Al3+ ions were significantly enhanced by 5.9 and 7.3 times, respectively. Longer lifetimes of the doped samples were observed for the 4S3/2 state and 4F9/2 state. The underlying reason for the UC enhancement by doping Al3+ ions was mainly ascribed to distortion of the local symmetry around Er3+ ions and adsorption reduction of organic ligands on the surface of NPs. In addition, the influence of doping Al3+ ions on the structure and morphology of the NPs samples was also discussed.

Photoluminescence properties of Mn2+/Yb3+ co-doped oxyfluoride glasses for solar cells application

NASA Astrophysics Data System (ADS)

Yan, Ying; Chen, Zeng; Jia, Xiyang; Li, Shengjun

2018-01-01

Mn2+/Yb3+ co-doped oxyfluoride glasses were facilely synthesized in the SiO2-Al2O3-Na2O-CaF2 system. Partial crystallization processed during the preparation of the glasses, by which small amounts of CaF2 nano-crystals were formed. Under ultraviolet and blue (370-500 nm) light excitation, an efficient down-conversion involving the emission of near-infrared is realized in the Mn2+/Yb3+ co-doped oxyfluoride glasses. The near-infrared emission peaks mainly at 976 nm and secondarily at 1020 nm, which is a comfortable match with the band gap of c-Si. The variation in visible and near-infrared spectra and the decay curves of Mn2+:4T1 → 6A1 emission have been investigated to verify the possible energy transfer from Mn2+ ions to Yb3+ ions. On analyzing the energy transfer processes theoretically and experimentally, we propose that quantum cutting and down-shifting processes may occur simultaneously in the samples. We suggest that the Mn2+-Yb3+ co-doped materials can provide a novel direction to realize UV-Vis to NIR down-conversion for Si solar cells.

Compositional dependence of broadband near-infrared downconversion and upconversion of Yb3+-doped multi-component glasses

NASA Astrophysics Data System (ADS)

Zhang, Liaolin; Xia, Yu; Shen, Xiao; Wei, Wei

2017-07-01

Yb3+ single-doped glasses show a strong excitation band in the 300-400 nm region, and efficiently emit photons with wavelengths of 920-1150 nm, and have potential applications in solar cells operating in an extraterrestrial situation. In this work, we systematically study the broadband near-infrared downconversion and upconversion of Yb3+-doped silicate, germanate, phosphate, tellurite and tungsten tellurite glasses. All samples show a broad excitation band in the 300-400 nm range, which is attributed to the charge transfer of the Yb3+-O2- couple. The position of the charge transfer band (CTB) shifts from 300 nm to longer wavelengths around 350 nm when the length of the R-O(Si, P, Ge, Te) increases. The longer R-O gives rise to a smaller central void for Yb3+, thus resulting in a small proportion of Yb3+ ions, thus leading to the blue-shift of the CTB. A smaller proportion of Yb3+ in silicate glasses causes in the strongest upconversion emission at 500 nm.

CW and tunable performances of Yb3+:LuAG transparent ceramics with different doping concentrations

NASA Astrophysics Data System (ADS)

Ma, Chaoyang; Zhu, Jiangfeng; Liu, Kai; Wen, Zicheng; Ma, Ran; Long, Jiaqi; Yuan, Xuanyi; Cao, Yongge

2017-07-01

We report the CW laser operation and wavelength tunability of 10 at%, 15 at% and 20 at% Yb3+-doping LuAG ceramics pumped at 970 nm. The absorption saturation effects were taken into account herein. For 10 at% Yb3+-doping sample, the maximum slop efficiency and output power was 60.7% and 1.8 W, respectively. Furthermore, the slop efficiencies of 52.3% (15 at%) and 46.5% (20 at%) were reported. What's more, the maximum optical-to-optical efficiency for our samples was determined to be 40.1%, 36.8%, and 33.1% at the incident pump power of 4 W, respectively. The round-trip cavity loss of the laser system based on our Yb3+:LuAG ceramics were evaluated. The tuning curve of a 20 at% Yb3+:LuAG ceramic extended from 1018 nm up to 1062 nm, and that of 10 at% and 15 at% samples became much more broader, making Yb3+:LuAG ceramics possible candidates for ultrashort pulse generation.

Investigation of Tm3+/Yb3+ co-doped germanate-tellurite glasses for efficient 2 µm mid-infrared laser materials

NASA Astrophysics Data System (ADS)

Dou, Aoju; Shen, Lingling; Wang, Ning; Cai, Yangjian; Cai, Muzhi; Guo, Yanyan; Huang, Feifei; Tian, Ying; Xu, Shiqing; Zhang, Junjie

2018-05-01

The Tm3+/Yb3+ co-doped germanate-tellurite glasses with good thermal properties were prepared. Based on the absorption spectra and the Judd-Ofelt theory, the J-O intensity parameters (Ω t ), radiative transition probability (276.78 s- 1), fluorescence lifetime (3.89 ms), absorption and emission cross sections ({σ e} = 1.35 × 10- 20 cm2) were calculated. The 2 µm mid-infrared emission resulting from the 3F4→3H6 transition of Tm3+ sensitized by Yb3+ was observed pumped by 980 nm LD. Besides, the energy transfer mechanism between Yb3+ and Tm3+ was thoroughly discussed. The measured 2 µm emission lifetime of Tm3+/Yb3+ co-doped glass can reach as high as 2.38 ms. The above results showed that Tm3+/Yb3+ co-doping glass could be expected to be a promising material to achieve high efficient 2 µm lasing with a 980 nm LD pumping.

All-fiber Yb-doped fiber laser passively mode-locking by monolayer MoS2 saturable absorber

NASA Astrophysics Data System (ADS)

Zhang, Yue; Zhu, Jianqi; Li, Pingxue; Wang, Xiaoxiao; Yu, Hua; Xiao, Kun; Li, Chunyong; Zhang, Guangyu

2018-04-01

We report on an all-fiber passively mode-locked ytterbium-doped (Yb-doped) fiber laser with monolayer molybdenum disulfide (ML-MoS2) saturable absorber (SA) by three-temperature zone chemical vapor deposition (CVD) method. The modulation depth, saturation fluence, and non-saturable loss of this ML-MoS2 are measured to be 3.6%, 204.8 μJ/cm2 and 6.3%, respectively. Based on this ML-MoS2SA, a passively mode-locked Yb-doped fiber laser has been achieved at 979 nm with pulse duration of 13 ps and repetition rate of 16.51 MHz. A mode-locked fiber laser at 1037 nm is also realized with a pulse duration of 475 ps and repetition rate of 26.5 MHz. To the best of our knowledge, this is the first report that the ML-MoS2 SA is used in an all-fiber Yb-doped mode-locked fiber laser at 980 nm. Our work further points the excellent saturable absorption ability of ML-MoS2 in ultrafast photonic applications.

Co-operative energy transfer in Yb3+-Er3+ co-doped SrGdxOy upconverting phosphor

NASA Astrophysics Data System (ADS)

Kumar, Ashwini; Pathak, Trilok K.; Dhoble, S. J.; . Terblans, J. J.; Swart, H. C.

2018-04-01

Upconversion nanoparticles (UCNPs) have shown considerable interest in many fields; however, low upconversion efficiency of UCNPs is still the most severe limitation of their applications. Yb3+ and Er3+ co-doped SrGd4O7/Gd2O3(SGO) upconversion (UC) phosphors were synthesized by a modified co-precipitation process. The UC properties were investigated by direct excitation with a 980 nm laser. It was observed that the as prepared materials showed relatively strong green emission, while upon the incorporation of the Er3+ ion, there was an increase in the upconversion luminescence intensity for the red component. The effect of different doping concentration of Er3+on the emission spectra and X-ray diffraction patterns of the UC materials have also been studied. The luminescence lifetimes and Commission Internationale de L'Eclairage coordinates for these as prepared samples were determined to understand the energy transfer (ET) mechanisms occurring between Yb3+ and Er3+ in the SGO host matrix. The UC luminescence intensity as a function of laser pump power was monitored and it was confirmed that the UC process in SGO:Yb3+/Er3+is a two-photon absorption process. The findings reported here are expected to provide a better approach for understanding of the ET mechanisms in the oxide based Yb3+/Er3+ co-doped UC phosphors. This study might be helpful in precisely defined applications where optical transitions are essential criterion and this can be easily achieved by smart tuning of the emission properties of Yb3+/Er3+ co-doped UC phosphors.

65-fs Yb-doped all-fiber laser using tapered fiber for nonlinearity and dispersion management.

PubMed

Yang, Peilong; Teng, Hao; Fang, Shaobo; Hu, Zhongqi; Chang, Guoqing; Wang, Junli; Wei, Zhiyi

2018-04-15

We implement an ultrafast Yb-doped all-fiber laser which incorporates tapered single-mode fibers for managing nonlinearity and dispersion. The tapered fiber placed in the oscillator cavity aims to broaden the optical spectrum of the intracavity pulse. At the oscillator output, we use another tapered fiber to perform pulse compression. The resulting 66.1-MHz Yb-doped all-fiber oscillator self-starts and generates 0.4-nJ, 65-fs pulses, which can serve as a compact and robust seed source for subsequent high-power, high-energy amplifiers.

Er{sup 3+}/Yb{sup 3+}co-doped bismuth molybdate nanosheets upconversion photocatalyst with enhanced photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, Rajesh; Gyawali, Gobinda; Cho, Sung Hun

2014-01-15

In this paper, we report the microwave hydrothermal synthesis of Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst. Crystal structure, morphology, elemental composition, optical properties and BET surface area were analyzed in detail. Infrared to visible upconversion luminescence at 532 nm and 546 nm of the co-doped samples was investigated under excitation at 980 nm. The results revealed that the co-doping of Er{sup 3+}/Yb{sup 3+} into Bi{sub 2}MoO{sub 6} exhibited enhanced photocatalytic activity for the decomposition of rhodamine B under simulated solar light irradiation. Enhanced photocatalytic activity can be attributed to the energy transfer between Er{sup 3+}/Yb{sup 3+} andmore » Bi{sub 2}MoO{sub 6} via infrared to visible upconversion from Er{sup 3+}/Yb{sup 3+} ion and higher surface area of the Bi{sub 2}MoO{sub 6} nanosheets. Therefore, this synthetic approach may exhibit a better alternative to fabricate upconversion photocatalyst for integral solar light absorption. - Graphical abstract: Schematic illustration of the upconversion photocatalysis. Display Omitted - Highlights: • Er{sup 3+}/Yb{sup 3+} co-doped Bi{sub 2}MoO{sub 6} upconversion photocatalyst is successfully synthesized. • We obtained the nanosheets having high surface area. • Upconversion of IR to visible light was confirmed. • Upconversion phenomena can be utilized for effective photocatalysis.« less

Up-conversion luminescence properties and energy transfer of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Jing; Mei, Lefu, E-mail: mlf@cugb.edu.cn; Deng, Junru

2015-11-15

Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} 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 BaLa{sub 2}ZnO{sub 5} among different co-doping concentrations. The structure of BaLa{sub 2}ZnO{sub 5}: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 Tm{sup 3+}/Yb{sup 3+}, indicating that Tm{sup 3+}/Yb{sup 3+} have successfully replaced La{sup 3+}. Under excitation at 980 nm, Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} phosphorsmore » present bright blue emission near 478 nm generated by the {sup 1}G{sub 4}→{sup 3}H{sub 6} transition and weak red emissions around 653 nm and 692 nm generated by the {sup 1}G{sub 4}→{sup 3}F{sub 4} and {sup 3}F{sub 3}→{sup 3}H{sub 6} transitions of Tm{sup 3+}, respectively. The UC luminescence properties of BaLa{sub 2}ZnO{sub 5} phosphors co-doped with different Tm{sup 3+}/Yb{sup 3+} concentrations were investigated, and the related UC mechanisms of Tm{sup 3+}/Yb{sup 3+} co-doped BaLa{sub 2}ZnO{sub 5} depending on pump power were studied in detail. - Graphical abstract: Up-conversion luminescence of BaLa{sub 2}ZnO{sub 5}:Tm{sup 3+}/Yb{sup 3+} and its crystal structure and up-conversion mechanisms. - Highlights: • Up-conversion phosphors BaLa{sub 2}ZnO{sub 5} co-doped with Tm{sup 3+}/Yb{sup 3+} were synthesized by high temperature solid-state reaction method. • The crystal structure of BaLa{sub 2}ZnO{sub 5} and the changes of cell parameters and volume of BaLa{sub 2}ZnO{sub 5} after doping Tm{sup 3+} and Yb{sup 3+} have been discussed. • Up-conversion luminescence properties and energy transfer between Tm{sup 3+} and Yb{sup 3+} in BaLa{sub 2}ZnO{sub 5} have been discussed in detail.« less

Yb-doped Gd2O2CO3: Structure, microstructure, thermal and magnetic behaviour

NASA Astrophysics Data System (ADS)

Artini, Cristina; Locardi, Federico; Pani, Marcella; Nelli, Ilaria; Caglieris, Federico; Masini, Roberto; Plaisier, Jasper Rikkert; Costa, Giorgio Andrea

2017-04-01

Structural and microstructural features, as well as thermal and magnetic properties of Yb-doped Gd2O2CO3, were investigated with the aim to clarify the location and the oxidation state of Yb within the structure, and its role in driving the extent of the (Gd1-xYbx)2O2CO3 solid solution. Yb is found in the 3+ oxidation state and it enters the structure only at the rare earth atomic site; the solubility limit results to be located in the close vicinity of x=0.25, and thermal analyses reveal a linear decrease of the decomposition temperature with increasing the Yb amount, in agreement with literature data. The structural analysis allows to exclude long-range clusterization of Yb and Gd, since both rare earths randomly distribute over the 4f atomic position, but relying on the results of the microstructural analysis, the presence of compositional inhomogenities at the local scale cannot be excluded. Not all the structural forms are documented for the pure rare earth dioxycarbonates [1]; in particular, while form I exists for each lanthanide ion, form II is stable only for the largest ones (from La to Dy); moreover, even if II-Ho2O2CO3 (rHo3+ CN8=1.015 Å [6]) is not reported to be stable, the existence of II-Y2O2CO3 (rY3+ CN8=1.019 Å [6]) has been claimed [7]. Based on the described evidence, the stability of hexagonal Yb-doped Gd2O2CO3 is not expected along the whole compositional range. As a general remark, not all the rare earth mixed dioxycarbonates exist: (Ce, Gd)2O2CO3, for instance, could not be obtained at any composition [8]; moreover, all the structural forms can be observed only in some mixed systems, such as for example (Gd, Nd)2O2CO3, by varying temperature and tuning the composition [9]. Rare earth dioxycarbonates are studied mainly for their CO2 sensing properties [10,11], and for their emission when properly doped with a luminescent lanthanide ion [12-17]. Recently, a study of this research group [18] revealed in Gd2O2CO3:4% Yb a phenomenon of

Yb3+/Ho3+ Co-Doped Apatite Upconversion Nanoparticles to Distinguish Implanted Material from Bone Tissue.

PubMed

Li, Xiyu; Chen, Haifeng

2016-10-07

The exploration of bone reconstruction with time requires the combination of a biological method and a chemical technique. Lanthanide Yb 3+ and Ho 3+ co-doped fluorapatite (FA:Yb 3+ /Ho 3+ ) and hydroxyapatite (HA:Yb 3+ /Ho 3+ ) particles with varying dopant concentrations were prepared by hydrothermal synthesis and thermal activation. Controllable green and red upconversion emissions were generated under 980 nm near-infrared excitation; the FA:Yb 3+ /Ho 3+ particles resulted in superior green luminescence, while HA:Yb 3+ /Ho 3+ dominated in red emission. The difference in the green and red emission behavior was dependent on the lattice structure and composition. Two possible lattice models were proposed for Yb 3+ /Ho 3+ co-doped HA and FA along the hydroxyl channel and fluorine channel of the apatite crystal structure. We first reported the use of the upconversion apatite particles to clearly distinguish implanted material from bone tissue on stained histological sections of harvested in vivo samples. The superposition of the tissue image and material image is a creative method to show the material-tissue distribution and interrelation. The upconversion apatite particles and image superposition method provide a novel strategy for long-term discriminable fluorescence tracking of implanted material or scaffold during bone regeneration.

Intervalence charge transfer luminescence: Interplay between anomalous and 5d − 4f emissions in Yb-doped fluorite-type crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barandiarán, Zoila, E-mail: zoila.barandiaran@uam.es; Seijo, Luis; Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, Universidad Autónoma de Madrid, 28049 Madrid

2014-12-21

In this paper, we report the existence of intervalence charge transfer (IVCT) luminescence in Yb-doped fluorite-type crystals associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. By means of embedded cluster, wave function theory ab initio calculations, we show that the widely studied, very broad band, anomalous emission of Yb{sup 2+}-doped CaF{sub 2} and SrF{sub 2}, usually associated with impurity-trapped excitons, is, rather, an IVCT luminescence associated with Yb{sup 2+}–Yb{sup 3+} mixed valence pairs. The IVCT luminescence is very efficiently excited by a two-photon upconversion mechanism where each photon provokes the same strong 4f{sup 14}–1A{sub 1g}→ 4f{sup 13}({sup 2}F{sub 7/2})5de{sub g}–1T{submore » 1u} absorption in the Yb{sup 2+} part of the pair: the first one, from the pair ground state; the second one, from an excited state of the pair whose Yb{sup 3+} moiety is in the higher 4f{sup 13}({sup 2}F{sub 5/2}) multiplet. The Yb{sup 2+}–Yb{sup 3+} → Yb{sup 3+}–Yb{sup 2+} IVCT emission consists of an Yb{sup 2+} 5de{sub g} → Yb{sup 3+} 4f{sub 7/2} charge transfer accompanied by a 4f{sub 7/2} → 4f{sub 5/2} deexcitation within the Yb{sup 2+} 4f{sup 13} subshell: [{sup 2}F{sub 5/2}5de{sub g},{sup 2}F{sub 7/2}] → [{sup 2}F{sub 7/2},4f{sup 14}]. The IVCT vertical transition leaves the oxidized and reduced moieties of the pair after electron transfer very far from their equilibrium structures; this explains the unexpectedly large band width of the emission band and its low peak energy, because the large reorganization energies are subtracted from the normal emission. The IVCT energy diagrams resulting from the quantum mechanical calculations explain the different luminescent properties of Yb-doped CaF{sub 2}, SrF{sub 2}, BaF{sub 2}, and SrCl{sub 2}: the presence of IVCT luminescence in Yb-doped CaF{sub 2} and SrF{sub 2}; its coexistence with regular 5d-4f emission in SrF{sub 2}; its absence in BaF{sub 2} and SrCl{sub 2}; the

Luminescence properties of Y2O3:Bi3+, Yb3+ co-doped phosphor for application in solar cells

NASA Astrophysics Data System (ADS)

Lee, E.; Kroon, R. E.; Terblans, J. J.; Swart, H. C.

2018-04-01

Bismuth (Bi3+) and ytterbium (Yb3+) co-doped yttrium oxide (Y2O3) phosphor powder was successfully synthesised using the co-precipitation technique. The X-ray diffraction (XRD) patterns confirmed that a single phase cubic structure with a Ia-3 space group was formed. The visible emission confirmed the two symmetry sites, C2 and S6, found in the Y2O3 host material and revealed that Bi3+ ions preferred the S6 site as seen the stronger emission intensity. The near-infrared (NIR) emission of Yb3+ increased significantly by the presence of the Bi3+ ions when compared to the singly doped Y2O3:Yb3+ phosphor with the same Yb3+ concentration. An increase in the NIR emission intensity was also observed by simply increasing the Yb3+ concentration in the Y2O3:Bi3+, Yb3+ phosphor material where the intensity increased up to x = 5.0 mol% of Yb3+ before decreasing due to concentration quenching.

Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate

NASA Astrophysics Data System (ADS)

Sawala, N. S.; Bajaj, N. S.; Omanwar, S. K.

2016-05-01

The materials Sr3-x(VO4)2:xYb were successfully synthesized by co-precipitation method varying the concentration of Yb3+ ions from 0 to 0.06 mol. It was characterize by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Yb3+ ion doped tristrontium vanadate (Sr3(VO4)2) phosphors that can convert a photon of UV region (349 nm) into photons of NIR region (978, 996 and 1026 nm). Hence this phosphor could be used as a quantum cutting (QC) luminescent convertor in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss due to spectral mismatch of the solar cells. The theoretical value of quantum efficiency (QE) was calculated from steady time decay measurement and the maximum efficiency approached up to 144.43%. The Sr(3-x) (VO4)2:xYb can be potentiality used for betterment of photovoltaic (PV) technology.

Single transverse mode laser in a center-sunken and cladding-trenched Yb-doped fiber.

PubMed

Liu, Yehui; Zhang, Fangfang; Zhao, Nan; Lin, Xianfeng; Liao, Lei; Wang, Yibo; Peng, Jinggang; Li, Haiqing; Yang, LuYun; Dai, NengLi; Li, Jinyan

2018-02-05

We report a novel center-sunken and cladding-trenched Yb-doped fiber, which was fabricated by a modified chemical vapor deposition process with a solution-doping technique. The simulation results showed that the fiber with a core diameter of 40 µm and a numerical aperture of 0.043 has a 1217 µm 2 effective mode area at 1080 nm. It is also disclosed that the leakage loss can be reduced lower than 0.01 dB/m for the LP 01 mode, while over 80 dB/m for the LP 11 mode by optimizing the bending radius as 14 cm. A 456 W laser output was observed in a MOPA structure. The laser slope efficiency was measured to be 79% and the M 2 was less than 1.1, which confirmed the single mode operation of the large mode area center-sunken cladding-trenched Yb-doped fiber.

Controlling the 1 μm spontaneous emission in Er/Yb co-doped fiber amplifiers.

PubMed

Sobon, Grzegorz; Kaczmarek, Pawel; Antonczak, Arkadiusz; Sotor, Jaroslaw; Abramski, Krzysztof M

2011-09-26

In this paper we present our experimental studies on controlling the amplified spontaneous emission (ASE) from Yb(3+) ions in Er/Yb co-doped fiber amplifiers. We propose a new method of controlling the Yb-ASE by stimulating a laser emission at 1064 nm in the amplifier, by providing a positive 1 μm signal feedback loop. The results are discussed and compared to a conventional amplifier setup without 1 μm ASE control and to an amplifier with auxiliary 1064 nm seeding. We have shown, that applying a 1064 nm signal loop in an Er/Yb amplifier can increase the output power at 1550 nm and provide stable operation without parasitic lasing at 1 μm. © 2011 Optical Society of America

Study of energy transfer and spectral downshifting in Ce, RE (RE = Nd and Yb) co-doped lanthanum phosphate

NASA Astrophysics Data System (ADS)

Sawala, N. S.; Omanwar, S. K.

2017-03-01

The phosphors LaPO4 (Lanthanum phosphate) doped with Ce(III)/Ce3+ and co-doped with Ce3+-Nd3+ and Ce3+-Yb3+ were effectively synthesized by conventional solid state reaction method. The prepared samples were characterized by powder X-ray diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infrared (NIR) and ultraviolet visible (UV-VIS) region. Additionally the luminescence time decay curves of samples were investigated to confirm energy transfer (ET) process. The Ce3+-Nd3+ ion co-doped LaPO4 phosphors can convert a photon of UV region (278 nm) into photons of NIR region (1058 nm). While Ce3+-Yb3+ ion doped LaPO4 phosphors convert photons of UV region (278 nm) into photons of NIR region (979 nm). The Ce3+ ion acts like sensitizer and Nd3+/Yb3+ ions act as activators. Both kinds of emissions are suitable for improving spectral response of solar cells.

High-efficiency, deep-junction, epitaxial InP solar cells on (100) and (111)B InP substrates

NASA Technical Reports Server (NTRS)

Venkatasubramanian, R.; Timmons, M. L.; Hutchby, J. A.; Walters, Robert J.; Summers, Geoffrey P.

1994-01-01

We report on the development and performance of deep-junction (approximately 0.25 micron), graded-emitter-doped, n(sup +)-p InP solar cells grown by metallorganic chemical vapor deposition (MOCVD). A novel, diffusion-transport process for obtaining lightly-doped p-type base regions of the solar cell is described. The I-V data and external quantum-efficiency response of these cells are presented. The best active-area AMO efficiency for these deep-junction cells on (100)-oriented InP substrates is 16.8 percent, with a J(sub SC) of 31.8 mA/sq cm, a V(sub OC) of 0.843 V, and a fill-factor of 0.85. By comparison, the best cell efficiency on the (111)B-oriented InP substrates was 15.0 percent. These efficiency values for deep-junction cells are encouraging and compare favorably with performance of thin-emitter (0.03 micron) epitaxial cells as well as that of deep-emitter diffused cells. The cell performance and breakdown voltage characteristics of a batch of 20 cells on each of the orientations are presented, indicating the superior breakdown voltage properties and other characteristics of InP cells on the (111)B orientation. Spectral response, dark I-V data, and photoluminescence (PL) measurements on the InP cells are presented with an analysis on the variation in J(sub SC) and V(sub OC) of the cells. It is observed, under open-circuit conditions, that lower-V(sub OC) cells exhibit higher band-edge PL intensity for both the (100) and (111)B orientations. This anomalous behavior suggests that radiative recombination in the heavily-doped n(sup +)-InP emitter may be detrimental to achieving higher V(sub OC) in n(sup +)-p InP solar cells.

White phosphor using Yb3+-sensitized Er3+-and Tm3+-doped sol-gel derived lead-fluorosilicate transparent glass ceramic excited at 980 nm

NASA Astrophysics Data System (ADS)

Tavares, M. C. P.; da Costa, E. B.; Bueno, L. A.; Gouveia-Neto, A. S.

2018-01-01

Generation of primary colors and white light through frequency upconversion using sol-gel derived 80SiO2:20PbF2 vitroceramic phosphors doped with Er3+, Er3+/Yb3+, Tm3+/Yb3+, and Er3+/Tm3+/Yb3+ excited at 980 nm is demonstrated. For Er3+ and Er3+/Yb3+ doped samples emissions were obtained in the blue (410 nm), green (530, and 550 nm) and red (670 nm) regions, corresponding to the 2H9/2 → 4I15/2,2H11/2 → 4I15/2, 4S3/2 → 4I152 and 4F9/2 → 4I15/2 transitions of Er3+, respectively. The codoping with Yb3+ ions altered the spectral profile of most of the emissions compared to the single doped samples, resulting in changes in the emitted color, in addition to a significant increase in the emission intensity. In Tm3+/Yb3+ co-doped samples visible emissions in the blue (480 nm), and red (650 nm), corresponding to transitions 1G4 → 3H6 and 1G4 → 3F4 of Tm3+, respectively, were obtained. The emission intensity around 480 nm overcome the red emission, and luminescence showed a predominantly blue tone. White light with CIE-1931 coordinates (0.36; 0.34) was produced by homogeneously mixing up powders of heat treated at 400 °C co-doped samples 5.0Er3+/5.0Yb3+ and 0.5Tm3+/2.5Yb3+ in the mass ratio of 13%, and 87%, respectively. The measured emission spectrum for a sample resulting from the mixture showed a profile with very good agreement with the spectrum found from the superimposition of the spectra of the co-doped samples.

Fluorosilicate and fluorophosphate superfluorescent multicore optical fibers co-doped with Nd3+/Yb3+

NASA Astrophysics Data System (ADS)

Kochanowicz, M.; Zmojda, J.; Dorosz, D.

2014-06-01

In the paper spectroscopic properties of two fluorosilicate and fluorophosphate glass systems co-doped with Nd3+/Yb3+ ions are investigated. As a result of optical excitation at the wavelength of 808 nm strong and wide emission in the 1 μm region corresponding to the superposition of optical transitions 4F3/2 → 4I11/2 (Nd3+) and 2F5/2 → 2F7/2 (Yb3+) can be observed. The optimization of Nd3+ → Yb3+ energy transfer in both glasses allows to manufacture multicore optical fibers with narrowing and red-shifting of amplified spontaneous emission (ASE) at 1.1 μm.

Spectroscopic and crystal-field analysis of new Yb-doped laser materials

NASA Astrophysics Data System (ADS)

Haumesser, Paul-Henri; Gaumé, Romain; Viana, Bruno; Antic-Fidancev, Elisabeth; Vivien, Daniel

2001-06-01

Crystal-field effects are very important as far as laser performances of Yb-doped materials are concerned. In order to simplify the interpretation of low-temperature spectra, two tools derived from a careful examination of crystal-field interaction are presented. Both approaches are successfully applied in the case of new Yb-doped materials, namely Ca3Y2(BO3)4 (CYB), Ca3Gd2(BO3)4 (CaGB), Sr3Y(BO3)3 (SrYBO), Ba3Lu(BO3)3 (BLuB), Y2SiO5 (YSO), Ca2Al2SiO7 (CAS) and SrY4(SiO4)3O (SYS). The 2F7/2 splitting is particularly large in these materials and favourable to a quasi-three-level laser operating scheme. Calculations performed using the point charge electrostatic model for these compounds and using a consistent set of effective atomic charges confirm the experimental results. This should permit to use this model in a predictive approach.

Pump-induced phase aberrations in Yb3+-doped materials(Conference Presentation)

NASA Astrophysics Data System (ADS)

Keppler, Sebastian; Tamer, Issa; Hornung, Marco; Körner, Jörg; Liebetrau, Hartmut; Hein, Joachim; Kaluza, Malte C.

2017-05-01

Optical pumping of laser materials is an effective way to create a population inversion necessary for laser operation. However, a fraction of the pump energy is always transfered as heat into the laser material, which is mainly caused by the quantum defect. For Yb3+-doped materials, the small energy difference between the pump level and the laser level and the pumping with narrowband high-power laser diodes result in a quantum defect of approx. 9%, which is significantly lower compared to other dopants e.g. Ti3+ (33%) or Nd3+ (24%). Due to the low heat introduction, high optical-to-optical efficiency and high repetition rate laser systems based on diode-pumping are well-suited for a number of applications. Here, however, laser beam quality is of crucial importance. Phase distortions and beam profile modulations can lead to optical damages as well as a significant reduction of the focal spot intensity. Pump-induced phase aberrations are the main cause for phase distortions of the amplified laser beam. The heat transferred to the material causes a change of the refractive index (dn/dT), thermal expansion and stress within the laser material, eventually leading to spatial phase aberrations (also called `thermal lens'). However, the spatially dependent distribution of the population inversion itself also leads to spatial phase aberrations. Since electron excitation directly leads to a change in the charge distribution of the laser active ions, the dynamic response of the material to external fields changes. These electronic phase aberrations (also called `population lens') are described by a change in the polarizability of the material. Due to the low quantum defect of Yb3+-doped materials, this effect becomes more important. We show the first comprehensive spatio-temporal characterization of the pump-induced phase aberration including both effects. A high-resolution interference measurement was carried out with time steps of 50µs for times during the pump period and

Growth, improved thermal stability and spectral properties of Yb3+-ions doped high temperature phase α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions

NASA Astrophysics Data System (ADS)

Pan, Shangke; Zhang, Jianyu; Pan, Jianguo

2018-02-01

To investigate the cause of the thermal instability of Yb3+-ions doped Ba3Gd(BO3)3 crystal grown from Czochralski technique, the low temperature phase β-Ba3Gd(BO3)3 powder was synthesized at the temperature of 800 °C. To inhibit the phase transition of high temperature phase Yb:α-Ba3Gd(BO3)3 during the crystal growth process, co-doping ions Sr2+, Ca2+ and La3+ ions were introduced in Yb:α-Ba3Gd(BO3)3 crystal. The melting point increased and the thermal stability of Yb:α-Ba3Gd(BO3)3 crystal was improved by co-doping ions. The absorption peaks of co-doped crystals centered at 976 nm with FWHM of 11, 11 and 12 nm and the absorption cross sections were 3.40 × 10-21 cm2, 4.00 × 10-21 cm2 and 2.66 × 10-21 cm2, respectively. The emission cross sections at 1040 nm were 2.19 × 10-21 cm2, 2.53 × 10-21 cm2 and 1.93 × 10-21 cm2, respectively. The fluorescence times of co-doped by Sr2+, Ca2+ and La3+ ions were shorter than that of Yb:α-Ba3Gd(BO3)3 crystal. So Yb:α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions will be more suitable for LD-pumping laser.

Concentration dependence and self-similarity of photodarkening losses induced in Yb-doped fibers by comparable excitation.

PubMed

Taccheo, Stefano; Gebavi, Hrvoje; Monteville, Achille; Le Goffic, Olivier; Landais, David; Mechin, David; Tregoat, Denis; Cadier, Benoit; Robin, Thierry; Milanese, Daniel; Durrant, Tim

2011-09-26

We report on an extensive investigation of photodarkening in Yb-doped silica fibers. A set of similar fibers, covering a large Yb concentration range, was made so as to compare the photodarkening induced losses. Careful measurements were made to ensure equal and uniform inversion for all the tested fibers. The results show that, with the specific set-up, the stretching parameter obtained through fitting has a very limited variation. This gives more meaning to the fitting parameters. Results tend to indicate a square law dependence of the concentration of excited ions on the final saturated loss. We also demonstrate self-similarity of loss evolution when experimental curves are simply normalized to fitting parameters. This evidence of self-similarity also supports the possibility of introducing a preliminary figure of merit for Yb-doped fiber. This will allow the impact of photodarkening on laser/amplifier devices to be evaluated. © 2011 Optical Society of America

Enhanced frequency upconversion study in Er3+/Yb3+ doped/codoped TWTi glasses

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar

2018-04-01

Er3+/Yb3+ doped/codoped TeO2-WO3-TiO2 (TWTi) glasses have been prepared by using the melt-quenching technique. The upconversion (UC) emission spectra of the developed glasses have been recorded upon 980 nm laser excitation. Three intense UC emission bands have been observed within the green and red region centered at ˜532 nm, ˜553 nm and ˜669 nm corresponding to the 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions respectively in the singly Er3+ doped glass. On introducing Yb3+ ions in the singly Er3+ doped glass, an enhancement of about ˜ 12 times and ˜50 times in the green and red bands respectively have been observed even at low pump power ˜ 364 mW followed by two photon absorption process. Colour tunability from yellowish green to pure green colour region has been observed on varying the pump power. The prepared glass can be used to produce NIR to green upconverter and colour tunable display devices.

Structure-Dependent Spectroscopic Properties of Yb3+-Doped Phosphosilicate Glasses Modified by SiO₂.

PubMed

Wang, Ling; Zeng, Huidan; Yang, Bin; Ye, Feng; Chen, Jianding; Chen, Guorong; Smith, Andew T; Sun, Luyi

2017-02-28

Yb 3+ -doped phosphate glasses containing different amounts of SiO₂ were successfully synthesized by the conventional melt-quenching method. The influence mechanism of SiO₂ on the structural and spectroscopic properties was investigated systematically using the micro-Raman technique. It was worth noting that the glass with 26.7 mol % SiO₂ possessed the longest fluorescence lifetime (1.51 ms), the highest gain coefficient (1.10 ms·pm²), the maximum Stark splitting manifold of ²F 7/2 level (781 cm -1 ), and the largest scalar crystal-field N J and Yb 3+ asymmetry degree. Micro-Raman spectra revealed that introducing SiO₂ promoted the formation of P=O linkages, but broke the P=O linkages when the SiO₂ content was greater than 26.7 mol %. Based on the previous 29 Si MAS NMR experimental results, these findings further demonstrated that the formation of [SiO₆] may significantly affect the formation of P=O linkages, and thus influences the spectroscopic properties of the glass. These results indicate that phosphosilicate glasses may have potential applications as a Yb 3+ -doped gain medium for solid-state lasers and optical fiber amplifiers.

Thermoelectric Performance of Yb-Doped Ba8Ni0.1Zn0.54Ga13.8Ge31.56 Type-I Clathrate Synthesized by High-Pressure Technique

NASA Astrophysics Data System (ADS)

Chen, Chen; Zhang, Long; Dong, Jianying; Xu, Bo

2017-05-01

Type I clathrates are a promising thermoelectric (TE) material for waste heat recovery applications. However, the TE figure-of-merit of type I clathrates still needs further improvement. In this study, Yb-doped Ba8- x Yb x Ni0.1Zn0.54 Ga13.8Ge31.56 (0 ≤ x ≤ 0.5) type I clathrates were synthesized using a high-pressure technique. Energy dispersive spectrometry confirmed successful Yb doping. An increased Yb doping level reduces electrical resistivity and suppresses lattice thermal conductivity while keeping the Seebeck coefficient almost unchanged. TE figure-of-merit of Ba7.7Yb0.3Ni0.1Zn0.54Ga13.8Ge31.56 type I clathrate was improved by 15% (0.91) at the highest measured temperature (900 K) compared with a Yb-free sample.

Design and characterization of Yb and Nd doped transparent ceramics for high power laser applications: recent advancements

NASA Astrophysics Data System (ADS)

Lapucci, A.; Vannini, M.; Ciofini, M.; Pirri, A.; Nikl, M.; Li, J.; Esposito, L.; Biasini, V.; Hostasa, J.; Goto, T.; Boulon, G.; Maksimov, R.; Gizzi, L.; Labate, L.; Toci, G.

2017-01-01

We report a review on our recent developments in Yttebium and Neodymium doped laser ceramics, along two main research lines. The first is the design and development of Yb:YAG ceramics with non uniform doping distribution, for the management of thermo-mechanical stresses and for the mitigation of ASE: layered structures have been produced by solid state reactive sintering, using different forming processes (spray drying and cold press of the homogenized powders, tape cast of the slurry); samples have been characterized and compared to FEM analysis. The second is the investigation of Lutetium based ceramics (such as mixed garnets LuYAG and Lu2O3); this interest is mainly motivated by the favorable thermal properties of these hosts under high doping. We recently obtained for the first time high efficiency laser emission from Yb doped LuYAG ceramics. The investigation on sesquioxides has been focused on Nddoped Lu2O3 ceramics, fabricated with the Spark Plasma Sintering method (SPS). We recently achieved the first laser emission above 1 W from Nd doped Lu2O3 ceramics fabricated by SPS.

Wavelength tunability of laser based on Yb-doped YGAG ceramics

NASA Astrophysics Data System (ADS)

Šulc, Jan; Jelínková, Helena; Jambunathan, Venkatesan; Miura, Taisuke; Endo, Akira; Lucianetti, Antonio; Mocek, TomáÅ.¡

2015-02-01

The wavelength tunability of diode pumped laser based on Yb-doped mixed garnet Y3Ga2Al3O12 (Yb:YGAG) ceramics was investigated. The tested Yb:YGAG sample (10% Yb/Y) was in the form of 2mm thick plane-parallel face-polished plate (without AR coatings). A fiber (core diameter 100 μm, NA= 0.22) coupled laser diode (LIMO, LIMO35-F100-DL980-FG-E) with emission at wavelength 969 nm, was used for longitudinal Yb:YGAG pumping. The laser diode was operating in the pulsed regime (2 ms pulse length, 10 Hz repetition rate). The duty-cycle 2% ensured a low thermal load even under the maximum diode pumping power amplitude 20W (ceramics sample was only air-cooled). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.01 - 1.09 μm, HT @ 0.97 μm) and curved (r = 150mm) output coupler with a reflectivity of ˜ 97% @ 1.01 - 1.09 μm. Wavelength tuning of the ytterbium laser was accomplished by using a birefringent filter (single 1.5mm thick quartz plate) placed inside the optical resonator at the Brewster angle between the output coupler and the laser active medium. The laser was continuously tunable over ˜ 58nm (from 1022nm to 1080 nm) and the tuning band was mostly limited by the free spectral range of used birefringent filter. The maximum output power amplitude 3W was obtained at wavelength 1046nm for absorbed pump power amplitude 10.6W. The laser slope efficiency was 34%.

Fluorescence properties of Yb3+-Er3+ co-doped phosphate glasses containing silver nanoparticles

NASA Astrophysics Data System (ADS)

Martínez Gámez, Ma A.; Vallejo H, Miguel A.; Kiryanov, A. V.; Licea-Jiménez, L.; Lucio M, J. L.; Pérez-García, S. A.

2018-04-01

Er3+-Yb3+ co-doped phosphate glasses containing silver nitrate (SN), were fabricated. Transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS) analyses were used to evidence the nucleation and presence of silver nanoparticles (SNP). The basic parameters of the glasses were inspected by means of absorption and fluorescence spectra, and fluorescence lifetimes under excitation at 916 nm (in-band of Yb3+), and at 406 nm (in-band of surface plasmon resonance given by the presence of SNP). The spectra as well as estimates for the basic parameters defining the lasing/amplifying potential of the glasses were studied as a function of SN concentration. The experimental results indicate that by increasing the SN content an enhancement of Er3+/Yb3+ fluorescence takes place.

Transparent Oxyfluoride Nano-Glass-Ceramics Doped with Pr3+ and Pr3+-Yb3+ for NIR Emission

NASA Astrophysics Data System (ADS)

Gorni, Giulio; Cosci, Alessandro; Pelli, Stefano; Pascual, Laura; Durán, Alicia; Pascual, M. J.

2016-12-01

Pr3+-Yb3+ co-doped oxyfluoride glasses and glass-ceramics (GC) containing LaF3 nanocrystals have been prepared to obtain NIR emission of Yb3+ ions upon Pr3+ excitation in the blue region of the visible spectrum. Two different compositions have been tested 0.1-0.5 Pr-Yb and 0.5-1 Pr-Yb, in addition to Pr3+ singly doped samples. The crystallization mechanism of the nano-glass-ceramics was studied by DTA revealing that it occurs from a constant number of nuclei, the crystal growth being limited by diffusion. HR-TEM demonstrated that phase separation acts as precursor for LaF3 crystallization and a detailed analysis of the chemical composition (EDXS) revealed the enrichment in RE3+ ions inside the initial phase separated droplets, from which the LaF3 crystals are formed. The RE3+ ions incorporation inside LaF3 crystals was also proved by photoluminescence measurements showing Stark splitting of the RE3+ ions energy levels in the glass-ceramic samples. Lifetimes measurements showed the existence of a better energy transfer process between Pr3+ and Yb3+ ions in the glass-ceramics compared to the as made glass, and the highest value of energy transfer efficiency is 59% and the highest theoretical quantum efficiency is 159%, obtained for glass-ceramics GC0.1-0.5 Pr-Yb treated at 620 ºC-40 h.

Phosphate-core silica-clad Er/Yb-doped optical fiber and cladding pumped laser.

PubMed

Egorova, O N; Semjonov, S L; Velmiskin, V V; Yatsenko, Yu P; Sverchkov, S E; Galagan, B I; Denker, B I; Dianov, E M

2014-04-07

We present a composite optical fiber with a Er/Yb co-doped phosphate-glass core in a silica glass cladding as well as cladding pumped laser. The fabrication process, optical properties, and lasing parameters are described. The slope efficiency under 980 nm cladding pumping reached 39% with respect to the absorbed pump power and 28% with respect to the coupled pump power. Due to high doping level of the phosphate core optimal length was several times shorter than that of silica core fibers.

Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles

NASA Astrophysics Data System (ADS)

Kshetri, Yuwaraj K.; Regmi, Chhabilal; Kim, Hak-Soo; Wohn Lee, Soo; Kim, Tae-Ho

2018-05-01

Yb3+ and Er3+ doped YVO4 (Yb3+/Er3+:YVO4) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb3+/Er3+:YVO4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2H11/2, 4S3/2 to 4I15/2 and 4F9/2 to 4I15/2 transitions of Er3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb3+. The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles.

PubMed

Kshetri, Yuwaraj K; Regmi, Chhabilal; Kim, Hak-Soo; Lee, Soo Wohn; Kim, Tae-Ho

2018-05-18

Yb 3+ and Er 3+ doped YVO 4 (Yb 3+ /Er 3+ :YVO 4 ) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb 3+ /Er 3+ :YVO 4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2 H 11/2 , 4 S 3/2 to 4 I 15/2 and 4 F 9/2 to 4 I 15/2 transitions of Er 3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb 3+ . The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

Optically active Er-Yb doped glass films prepared by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Serna, R.; Ballesteros, J. M.; Jiménez de Castro, M.; Solis, J.; Afonso, C. N.

1998-08-01

Active rare-earth Er3+-Yb3+ co-doped phosphate glass films are produced in a single step by pulsed laser deposition. The films are multimode waveguides and exhibit the highest refractive index, optical density and 1.54 μm photoluminescence intensity and lifetime when deposited at low oxygen pressure (Pox⩽4×10-5 Torr). The density of the films obtained under these conditions is higher than that of the target material as a consequence of the high kinetic energy of the species generated during ablation. Luminescent emission can be excited by optical pumping the Er3+ ions either directly or through cross-relaxation of the Yb3+. Post-deposition annealing allows us to improve the luminescence performance.

High Efficiency InP Solar Cells from Low Toxicity Tertiarybutylphosphine

NASA Technical Reports Server (NTRS)

Hoffman, Richard W., Jr.; Fatemi, Navid S.; Wilt, David M.; Jenkins, Phillip P.; Brinker, David J.; Scheiman, David A.

1994-01-01

Large scale manufacture of phosphide based semiconductor devices by organo-metallic vapor phase epitaxy (OMVPE) typically requires the use of highly toxic phosphine. Advancements in phosphine substitutes have identified tertiarybutylphosphine (TBP) as an excellent precursor for OMVPE of InP. High quality undoped and doped InP films were grown using TBP and trimethylindium. Impurity doped InP films were achieved utilizing diethylzinc and silane for p and n type respectively. 16 percent efficient solar cells under air mass zero, one sun intensity were demonstrated with Voc of 871 mV and fill factor of 82.6 percent. It was shown that TBP could replace phosphine, without adversely affecting device quality, in OMVPE deposition of InP thus significantly reducing toxic gas exposure risk.

Gain-switched laser diode seeded Yb-doped fiber amplifier delivering 11-ps pulses at repetition rates up to 40-MHz

NASA Astrophysics Data System (ADS)

Ryser, Manuel; Neff, Martin; Pilz, Soenke; Burn, Andreas; Romano, Valerio

2012-02-01

Here, we demonstrate all-fiber direct amplification of 11 picosecond pulses from a gain-switched laser diode at 1063 nm. The diode was driven at a repetition rate of 40 MHz and delivered 13 μW of fiber-coupled average output power. For the low output pulse energy of 0.33 pJ we have designed a multi-stage core pumped preamplifier based on single clad Yb-doped fibers in order to keep the contribution of undesired amplified spontaneous emission as low as possible and to minimize temporal and spectral broadening. After the preamplifier we reduced the 40 MHz repetition rate to 1 MHz using a fiber coupled pulse-picker. The final amplification was done with a cladding pumped Yb-doped large mode area fiber and a subsequent Yb-doped rod-type fiber. With our setup we achieved amplification of 72 dBs to an output pulse energy of 5.7 μJ, pulse duration of 11 ps and peak power of >0.6 MW.

2.7 μm emission properties of Er3+ doped tungsten-tellurite glass sensitized by Yb3+ ions.

PubMed

Guo, Yanyan; Ma, Yaoyao; Huang, Feifei; Peng, Yapei; Zhang, Liyan; Zhang, Junjie

2013-07-01

With a 980 nm laser diode (LD) pumped, the sensitized effect of Yb(3+) ions on 2.7 μm emission properties and energy transfer mechanism in Yb(3+)/Er(3+) co-doped tungsten-tellurite glass were investigated in present paper. Based on absorption spectra, Judd-Ofelt parameters and radiative transition probabilities were calculated and analyzed. The emission spectra were tested and the optimized concentration ratio of Yb(3+) to Er(3+) ions was found to be 3:0.5 with a largest calculated emission cross-section (6.05×10(-21) cm(2)) corresponding to Er(3+):(4)I11/2→(4)I13/2 transition. When the concentration ratio of Yb(3+) to Er(3+) ions was 4:0.5, 1.5 μm and 2.7 μm emission decreased while up-conversion increased. The decreased 1.5 μm and 2.7 μm emission were induced by the saturation of Er(3+):(4)I13/2 level. In brief, the advantageous spectroscopic characteristics indicated that Yb(3+)/Er(3+) co-doped tungsten-tellurite glass may be a promising candidate for application of 2.7 μm emission. Copyright © 2013 Elsevier B.V. All rights reserved.

Enhancement of luminescence emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor by Li{sup +} co-doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavrilović, Tamara V.; Jovanović, Dragana J., E-mail: draganaj@vinca.rs; Lojpur, Vesna M.

2014-09-15

This paper demonstrates the effects of Li{sup +} co-doping on the structure, morphology, and luminescence properties of GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor prepared using a high-temperature solid-state chemistry method. The GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} powders synthesized with the Li{sup +} co-dopant (in concentrations of 0, 5, 10, and 15 mol%) are characterized by X-ray powder diffraction, scanning electron microscopy, and photoluminescence spectroscopy. Structural analysis showed that powders co-doped with Li{sup +} have larger crystallite sizes and slightly smaller crystal lattice parameters than powders prepared without Li{sup +} ions. Photoluminescence down-conversion (345-nm excitation) and up-conversion (980-nm excitation) spectra show characteristic Er{supmore » 3+} emissions, with the most intense bands peaking at 525 nm ({sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition) and 552 nm ({sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}). The intensity of up-conversion emission from GdVO{sub 4}:Er{sup 3+}/Yb{sup 3+} is enhanced (by a factor of four) by co-doping with 5 mol% of Li{sup +} ions. The mechanisms responsible for this emission enhancement are discussed. - Graphical abstract: UC emission spectra for GdVO{sub 4}:1.5-mol% Er{sup 3+}/20-mol% Yb{sup 3+} powders co-doped with different concentrations of Li{sup +} ions, recorded under 980-nm excitation. - Highlights: • 5-mol% Li{sup +} co-doped powders have 400% enhanced up-conversion emission intensity. • 15-mol% Li{sup +} co-doping produces 40% higher emission in down-conversion. • Li{sup +} co-doped powders have larger crystallite size and smaller lattice parameters.« less

Sensitivity-enhanced Tm3+/Yb3+ co-doped YAG single crystal optical fiber thermometry based on upconversion emissions

NASA Astrophysics Data System (ADS)

Yu, Lu; Ye, Linhua; Bao, Renjie; Zhang, Xianwei; Wang, Li-Gang

2018-03-01

Optical thermometry based on Y3Al5O12 (YAG) single crystal optical fiber with end Tm3+/Yb3+ co-doped is presented. The YAG crystal fiber with end Tm3+/Yb3+ co-doped was grown by laser heated pedestal growth (LHPG) method. Under a 976 nm laser diode excitation, the upconversion (UC) emissions, originating from 3F2,3 →3H6 and 3H4 →3H6 transitions of Tm3+ ions, were investigated in the temperature range from 333 K to 733 K. Interestingly, the UC emission intensity of 3F2,3 →3H6 transition was significantly enhanced with increase of temperature, as compared with the other Tm3+/Yb3+ co-doped materials. The temperature dependence of fluorescence intensity ratio (FIR) of these two emission bands (3F2,3/3H4 →3H6) suggests that this doped YAG crystal fiber can be used as a highly sensitive optical thermal probe, which demonstrates a high absolute sensitivity with the maximum value of 0.021 K-1 at 733 K. In addition, due to the compact structure, strong mechanical strength and high thermal stability, such thermal probe may be a more promising candidate for temperature sensor with a high spatial resolution.

Understanding the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, Rajesh; Choi, Jinhyuk; Narro-García, R.

2014-08-15

In this paper we report the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals synthesized via microwave assisted sol–gel processing route. Structural, morphological and upconversion luminescence properties were investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and Upconversion Photoluminescence spectra analysis. Results revealed that the oval shaped BaMoO{sub 4} nanocrystals ranging in size from 40 to 60 nm having tetragonal scheelite crystal structure were obtained by sol–gel route. The infrared to visible upconversion luminescence has been investigated in Er{sup 3+}/Yb{sup 3+} co-doped in BaMoO{sub 4}with different Yb{supmore » 3+} concentrations. Intense green upconversion emissions around 528, 550 nm, and red emission at 657 nm corresponding to the {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, and {sup 4}F{sub 9/2} transitions, respectively to the {sup 4}I{sub 15/2} ground state were observed when excited by CW laser radiation at 980 nm. The green emissions were greatly enhanced after the addition of sensitizer (Yb{sup 3+} ions). The effect of Yb{sup 3+} on the upconversion luminescence intensity was analyzed and explained in terms of the energy transfer process based. The reported work establishes the understanding of molybdates as an alternative host material for upconversion luminescence. - Graphical abstract: Infrared to visible upconversion luminescence of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. - Highlights: • Nanocrystals were synthesized by microwave assisted sol–gel processing route. • Strong green emissions were observed in Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. • Provides an insight on Upconversion luminescence properties of oxides host materials.« less

Crystal Growth and Luminescence Properties of Yb-doped Gd3Al2Ga3O12 Infra-red Scintillator

NASA Astrophysics Data System (ADS)

Suzuki, Akira; Kurosawa, Shunsuke; Nagata, Shinji; Yamamura, Tomoo; Pejchal, Jan; Yamaji, Akihiro; Yokota, Yuui; Shirasaki, Kenji; Homma, Yoshiya; Aoki, Dai; Shikama, Tatsuo; Yoshikawa, Akira

2014-07-01

1-mol%-Yb-doped Gd3Al2Ga3O12 infra-red scintillator crystal has been studied as a novel implantable radiation monitor in radiation therapy. Powder X-ray diffraction measurement and chemical analysis with a field emission scanning microscope and wavelength dispersive spectrometer determined its garnet structure and average chemical composition of Yb0.03±0.01Gd2.99±0.07Al2.21±0.08Ga2.64±0.09O12.10±0.09. Transmittance measurements reached high values of approximately 70% in the human body transparency region between 650 to 1200 nm. Photoluminescence peaks were detected around 970 and 1030 nm under the 940 nm excitation with a Xe lamp. Infra-red scintillation emissions were clearly observed around 970 and 1030 nm due to Yb3+ 4f-4f transitions under X-ray excitation. Therefore, these results suggest that Yb-doped Gd3Al2Ga3O12 might be used as an infra-red scintillator material.

Yb-doped passively mode-locked fiber laser with Bi2Te3-deposited

NASA Astrophysics Data System (ADS)

Li, Lu; Yan, Pei-Guang; Wang, Yong-Gang; Duan, Li-Na; Sun, Hang; Si, Jin-Hai

2015-12-01

In this study we present an all-normal-dispersion Yb-doped fiber laser passively mode-locked with topological insulator (Bi2Te3) saturable absorber. The saturable absorber device is fabricated by depositing Bi2Te3 on a tapered fiber through using pulsed laser deposition (PLD) technology, which can give rise to less non-saturable losses than most of the solution processing methods. Owing to the long interaction length, Bi2Te3 is not exposed to high optical power, which allows the saturable absorber device to work in a high power regime. The modulation depth of this kind of saturable absorber is measured to be 10%. By combining the saturable absorber device with Yb-doped fiber laser, a mode-locked pulse operating at a repetition rate of 19.8 MHz is achieved. The 3-dB spectral width and pulse duration are measured to be 1.245 nm and 317 ps, respectively. Project supported by the National Natural Science Foundation of China (Grant No. 61378024) and the Natural Science Fund of Guangdong Province, China (Grant No. S2013010012235).

Enhanced NIR downconversion luminescence by precipitating nano Ca5(PO4)3F crystals in Eu2+-Yb3+ co-doped glass

NASA Astrophysics Data System (ADS)

Li, Chen; Song, Zhiguo; Li, Yongjin; Lou, Kai; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Wang, Xue; Wang, Qi; Wan, Ronghua

2013-10-01

Eu2+-Yb3+ co-doped transparent glass-ceramic containing nano-Ca5(PO4)3F (FAP) was prepared in reducing atmosphere. XRD and TEM analysis indicated that nano-FAP about 40 nm precipitated homogeneously in glass matrix after heat treatment. Confirmed by spectroscopy measurements, the crystal-like absorption and emission of Eu2+ indicated the partition of Eu2+ into FAP nanocrystals in glass ceramic. NIR emission due to the transition 2F→2F of Yb3+ ions (about 980-1100 nm) was observed from glasses under ultraviolet excitation, ascribed to downconversion from Eu2+ to Yb3+, which can be enhanced by precipitating nano-FAP crystals. The results indicated that Eu2+-Yb3+ co-doped glass-ceramic embedding with nano-FAP is a promising candidate as downconversion materials for enhancing conversion efficiency of solar cells.

Different polarization dynamic states in a vector Yb-doped fiber laser.

PubMed

Li, Xingliang; Zhang, Shumin; Han, Huiyun; Han, Mengmeng; Zhang, Huaxing; Zhao, Luming; Wen, Fang; Yang, Zhenjun

2015-04-20

Different polarization dynamic states in an unidirectional, vector, Yb-doped fiber ring laser have been observed. A rich variety of dynamic states, including group velocity locked polarization domains and their splitting into regularly distributed multiple domains, polarization locked square pulses and their harmonic mode locking counterparts, and dissipative soliton resonances have all been observed with different operating parameters. We have also shown experimentally details of the conditions under which polarization-domain-wall dark pulses and bright square pulses form.

Broadband near-infrared downconversion luminescence in Yb3+-doped BaZn2(BO3)2

NASA Astrophysics Data System (ADS)

Yu, Hua; Deng, Degang; Su, Weitao; Li, Chenxia; Xu, Shiqing

2018-06-01

BaZn2(BO3)2 self-activated phosphors were prepared by the conventional high temperature solid-state method. The PL spectra of BaZn2(BO3)2 powders prepared under reductive and air atmosphere consist of a weak ultraviolet emission band (∼410 nm) and a broad emission band which were centered at ∼ 500 and 545 nm, respectively. According to the spectral analysis and EPR results, the green and yellow emissions may arise from the transitions of photo-generated electron close to the conduction band to the deeply trapped hole in single ionized oxygen vacancy (V+ o) centers and single negatively charged interstitial oxygen ion (O- i), respectively. An efficient broadband near-infrared (NIR) quantum cutting was demonstrated in Yb3+ doped BaZn2(BO3)2 phosphor. Upon excitation with an ultraviolet photon at 375 nm, the emissions of two NIR photons at 983 nm from Yb3+ ions were achieved. The dependences of the visible and NIR emissions, the decay lifetime, the energy transfer efficiency, and the quantum efficiency on the Yb3+ doping content were investigated in detail. The results indicated that the maximum energy transfer and the corresponding downconversion quantum efficiency could reach between 68.5% and 168.5%.

Structure-Dependent Spectroscopic Properties of Yb3+-Doped Phosphosilicate Glasses Modified by SiO2

PubMed Central

Wang, Ling; Zeng, Huidan; Yang, Bin; Ye, Feng; Chen, Jianding; Chen, Guorong; Smith, Andew T.; Sun, Luyi

2017-01-01

Yb3+-doped phosphate glasses containing different amounts of SiO2 were successfully synthesized by the conventional melt-quenching method. The influence mechanism of SiO2 on the structural and spectroscopic properties was investigated systematically using the micro-Raman technique. It was worth noting that the glass with 26.7 mol % SiO2 possessed the longest fluorescence lifetime (1.51 ms), the highest gain coefficient (1.10 ms·pm2), the maximum Stark splitting manifold of 2F7/2 level (781 cm−1), and the largest scalar crystal-field NJ and Yb3+ asymmetry degree. Micro-Raman spectra revealed that introducing SiO2 promoted the formation of P=O linkages, but broke the P=O linkages when the SiO2 content was greater than 26.7 mol %. Based on the previous 29Si MAS NMR experimental results, these findings further demonstrated that the formation of [SiO6] may significantly affect the formation of P=O linkages, and thus influences the spectroscopic properties of the glass. These results indicate that phosphosilicate glasses may have potential applications as a Yb3+-doped gain medium for solid-state lasers and optical fiber amplifiers. PMID:28772601

Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

PubMed

Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

2013-11-21

NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times.

Tm3+/Yb3+ co-doped tellurite glass with silver nanoparticles for 1.85 μm band laser material

NASA Astrophysics Data System (ADS)

Huang, Bo; Zhou, Yaxun; Cheng, Pan; Zhou, Zizhong; Li, Jun; Jin, Wei

2016-10-01

Tm3+/Yb3+ co-doped tellurite glasses with different silver nanoparticles (Ag NPs) concentrations were prepared using the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, transmission electron microscopy (TEM) images, differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. Under the excitation of 980 nm laser diode (LD), the 1.85 μm band fluorescence emission of Tm3+ ions enhances significantly in the presence of Ag NPs with average diameter of ∼8 nm and local surface Plasmon resonance (LSPR) band of ∼590 nm, which is mainly attributed to the increased local electric field induced by Ag NPs at the proximity of doped rare-earth ions on the basis of energy transfer from Yb3+ to Tm3+ ions. An improvement by about 110% of fluorescence intensity is observed in the Tm3+/Yb3+ co-doped tellurite glass containing 0.5 mol% amount of AgNO3 while the prepared glass samples possess good thermal stability and amorphous structural nature. Meanwhile, the Judd-Ofelt intensity parameters Ωt (t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were determined based on the Judd-Ofelt theory to reveal the enhanced effects of Ag NPs on the 1.85 μm band spectroscopic properties, and the energy transfer micro-parameters and phonon contribution ratios were calculated based on the non-resonant energy transfer theory to elucidate the energy transfer mechanism between Yb3+ and Tm3+ ions. The present results indicate that the prepared Tm3+/Yb3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising lasing media applied for 1.85 μm band solid-state lasers and amplifiers.

Monolithic all-fiber repetition-rate tunable gain-switched single-frequency Yb-doped fiber laser.

PubMed

Hou, Yubin; Zhang, Qian; Qi, Shuxian; Feng, Xian; Wang, Pu

2016-12-12

We report a monolithic gain-switched single-frequency Yb-doped fiber laser with widely tunable repetition rate. The single-frequency laser operation is realized by using an Yb-doped distributed Bragg reflection (DBR) fiber cavity, which is pumped by a commercial-available laser diode (LD) at 974 nm. The LD is electronically modulated by the driving current and the diode output contains both continuous wave (CW) and pulsed components. The CW component is set just below the threshold of the single-frequency fiber laser for reducing the requirement of the pump pulse energy. Above the threshold, the gain-switched oscillation is trigged by the pulsed component of the diode. Single-frequency pulsed laser output is achieved at 1.063 μm with a pulse duration of ~150 ns and a linewidth of 14 MHz. The repetition rate of the laser output can be tuned between 10 kHz and 400 kHz by tuning the electronic trigger signal. This kind of lasers shows potential for the applications in the area of coherent LIDAR etc.

Cr3+-Doped Yb3Ga5O12 Nanophosphor: Synthesis, Optical, EPR, Studies

NASA Astrophysics Data System (ADS)

Singh, Vijay; Sivaramaiah, G.; Rao, J. L.; Singh, N.; Pathak, M. S.; Jirimali, H. D.; Singh, Pramod K.; Srivastava, Anoop K.; Dhoble, S. J.; Mohapatra, M.

2016-08-01

Gallium garnets of lanthanides are multifunctional materials especially known for their complicated structure and magnetic properties. In addition, with a suitable transition metal dopant ion, these matrices have been proved to be excellent materials for lasers. In particular, gallium garnet of ytterbium (Yb3Ga5O12) is known to possess excellent properties with regards to these applications. In this connection, Yb3Ga5O12 doped with Cr3+ nanophosphors were synthesized by a solution combustion route. The synthesized material was characterized by powder x-ray diffraction and scanning electron microscopy for phase purity and homogenous morphology. In order to ascertain the oxidation state of the doped ion, diffuse reflectance (DRF), photoluminescence (PL) and electron paramagnetic resonance (EPR) experiments were performed on the sample. The DRF and PL data suggested the stabilisation of the trivalent Cr ion in the matrix. The EPR spectra exhibited two resonance signals with effective g values at g ≈ 7.6 and 4. The EPR data corroborated the DRF and PL results, suggesting the stabilisation of Cr3+ in the matrix at octahedral-type geometries.

Origin of near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+)co-doped fluorotellurite glasses under different excitations.

PubMed

Huang, Feifei; Liu, Xueqiang; Ma, Yaoyao; Kang, Shuai; Hu, Lili; Chen, Danping

2015-02-04

We report the near to middle infrared luminescence and energy transfer process of Er(3+)/Yb(3+) co-doped fluorotellurite glasses under 980, 1550 and 800 nm excitations, respectively. Using a 980 nm laser diode pump, enhanced 1.5 and 2.7 μm emissions from Er(3+):I13/2→(4)I15/2 and I11/2→(4)I13/2 transitions are observed, in which Yb(3+) ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb(3+) can also be used as an acceptor and intensive upconversion luminescence of around 1000 nm is achieved from Er(3+):I11/2→(4)I15/2 and Yb(3+): F5/2→(4)F7/2 transitions using 1550 nm excitation. In addition, the luminescence properties and variation trendency by 800 nm excitation is similar to that using 1550 nm excitation. The optimum Er(3+) and Yb(3+) ion ratio is 1:1.5 and excess Yb(3+) ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er(3+)/Yb(3+) co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells.

Yb:YAG disc for high energy laser systems

NASA Astrophysics Data System (ADS)

Nejezchleb, Karel; Kubát, Jan; Å ulc, Jan; Jelínková, Helena

2017-02-01

Large Yb:YAG crystals were grown using of new improved technology enabling to produce YAG crystals without central growth defect. The crystals diameter reached 115-120mm and their central part was used for manufacturing of discs with the diameter larger than 55 mm. Both sides of this discs were polished and coated. Doping concentration of Yb3+ ions in Yb:YAG crystals was measured using of X-ray fluorescence spectrometry. Absorption coefficient of Yb:YAG was measured for different doping concentration of Yb3+ ions. Fluorescence decay time of Yb:YAG was measured at temperatures of 300K and 80 K. We found the fluorescence decay time of the values of 0.95-1 ms at both temperatures stable and independent on the Yb3+ doping concentration in the range of 1-10 at.% Yb/Y demonstrating high chemical purity of grown crystals. Optical homogeneity as measured using of Fizeau double pass interferometer at 633nm resulted with PV values lower than 0.15 λ on clear aperture of 35 mm. Polished surfaces were ideally parallel with the wedge lower than 2 arcsec. Uniformity of laser properties of Yb:YAG was verified by scanning of the disc as active media in plan-convex pulsed laser resonator pumped by semiconductor diode (wavelength 969 nm, pumping beam diameter 100 μm). It was confirmed, that newly developed technology allows to manufacture very large high quality Yb:YAG discs suitable for high power lasers and amplifiers.

Enhanced infrared-to-visible up-conversion emission and temperature sensitivity in (Er3+,Yb3+, and W6+) tri-doped Bi4Ti3O12 ferroelectric oxide

NASA Astrophysics Data System (ADS)

Bokolia, Renuka; Mondal, Manisha; Rai, V. K.; Sreenivas, K.

2017-02-01

Strong up conversion (UC) luminescence at 527, 550, and 662 nm is compared under an excitation of 980 nm in single doped (Er3+), co-doped (Er3+/Yb3+), and (Er3+/Yb3+/W6+) tri-doped bismuth titanate (Bi4Ti3O12). For the co-doped system, the frequency (UC) emission intensity due to Er3+ ions is enhanced significantly in the green bands due to the efficient energy transfer from Yb3+ to Er3+ ions. Further increase in the emission intensity is seen with non-luminescent W6+ ions in the tri-doped system due to the modification in the local crystal field around the Er3+ ions, and is evidenced through a gradual change in the crystal structure of the host lattice with increasing W6+ content. The observed changes in the fluorescence lifetime and the associated energy transfer mechanisms are discussed. A progressive reduction of the lifetime of the 4S3/2 levels of Er3+ ions from 72 to 58.7 μs with the introduction of Yb3+ and W6+ dopant increases the transition probability and enhances the UC emission intensity. The efficiency of the energy transfer process ( η ) in the co-doped and tri-doped systems is found to be 9.4% and 18.6%, respectively, in comparison to the single doped system. Temperature sensing based on the fluorescence intensity ratio (FR) technique shows high sensitivity (0.0123 K-1) in the high temperature range (293 to 523 K) for an optimum content of Er3+, Yb3+, and W6+ with x = 0.03, y = 0.18, and z = 0.06 at. % in the tri-doped Bi4-x-yErxYbyTi3-zWzO12 ferroelectric composition, and is found useful for potential applications in optical thermometry.

Electroluminescent Yb2O3:Er and Yb2Si2O7:Er nanolaminate films fabricated by atomic layer deposition on silicon

NASA Astrophysics Data System (ADS)

Ouyang, Zhongtao; Yang, Yang; Sun, Jiaming

2018-06-01

Atomic layer doped Yb2O3:Er and Yb2Si2O7:Er nanolaminate films are fabricated on silicon by atomic layer deposition, and ∼1530 nm electroluminescence (EL) is obtained from the metal-oxide-semiconductor light-emitting devices (MOSLEDs) based on these films. The Yb2O3 films transfer to Yb2Si2O7 phase after annealing above 1000 °C. Intense photoluminescence from Yb2Si2O7 film confirms high efficiency and energy transfer under optical excitation, but the limited electron conduction restricts the EL performance. EL from the Yb2O3:Er MOSLED outperforms, presenting an external quantum efficiency up to 8.5% and the power efficiency of 1 × 10-3. The EL is derived to result from the impact excitation of Er3+ ions by hot electrons, which stem from Fowler-Nordheim tunneling mechanism under sufficient bias voltage. The critical distance for the cross relaxation of doped Er3+ ions in nanolaminate Yb2O3 matrix is experimentally determined to be ∼3 nm. Such devices manifest the technological potential of Er-doped Yb-oxides for applications in silicon-based optoelectronics.

Two-wavelength, passive self-injection-controlled operation of diode-pumped cw Yb-doped crystal lasers.

PubMed

Louyer, Yann; Wallerand, Jean-Pierre; Himbert, Marc; Deneva, Margarita; Nenchev, Marin

2003-09-20

We demonstrate and investigate a peculiar mode of cw Yb3+-doped crystal laser operation when two emissions, at two independently tunable wavelengths, are simultaneously produced. Both emissions are generated from a single pumped volume and take place in either a single beam or spatially separated beams. The laser employs original two-channel cavities that use a passive self-injection-locking (PSIL) control to reduce intracavity loss. The advantages of the application of the PSIL technique and some limitations are shown. The conditions for two-wavelength multimode operation of the cw quasi-three-level diode-pumped Yb3+ lasers and the peculiarity of such an operation are carried out both theoretically and experimentally. The results reported are based on the example of a Yb3+:GGG laser but similar results are also obtained with a Yb3+:YAG laser. The laser operates in the 1023-1033-nm (1030-1040-nm) range with a total output power of 0.4 W. A two-wavelength, single longitudinal mode generation is also obtained.

A global design of high power Nd 3+-Yb 3+ co-doped fiber lasers

NASA Astrophysics Data System (ADS)

Fan, Zhang; Chuncan, Wang; Tigang, Ning

2008-09-01

A global optimization method - niche hybrid genetic algorithm (NHGA) based on fitness sharing and elite replacement is applied to optimize Nd3+-Yb3+ co-doped fiber lasers (NYDFLs) for obtaining maximum signal output power. With a objective function and different pumping powers, five critical parameters (the fiber length, L; the proportion of pump power for pumping Nd3+, η; Nd3+ and Yb3+ concentrations, NNd and NYb and output mirror reflectivity, Rout) of the given NYDFLs are optimized by solving the rate and power propagation equations. Results show that dividing equally the input pump power among 808 nm (Nd3+) and 940 nm (Yb3+) is not an optimal choice and the pump power of Nd3+ ions should be kept around 10-13.78% of the total pump power. Three optimal schemes are obtained by NHGA and the highest slope efficiency of the laser is able to reach 80.1%.

Broadband ∼3 μm mid-infrared emission in Dy3+/Yb3+ co-doped germanate glasses

NASA Astrophysics Data System (ADS)

Shen, Lingling; Wang, Ning; Dou, Aoju; Cai, Yangjian; Tian, Ying; Huang, Feifei; Xu, Shiqing; Zhang, Junjie

2018-01-01

The Dy3+/Yb3+ co-doped germanate glasses with good thermal stability have been prepared by the conventional melt quenching method. The J-O intensity parameters and radiative properties such as spontaneous transition probilities (Arad), fluorescence branching ratios (β) and radiative lifetimes (τrad) were investigated according to the absorption spectrum based on Judd-Ofelt theory. An intense emission around ∼3 μm with the FWHM reaching to 322 nm was obtained in present glasses excited by 980 nm LD. The high spontaneous transition probability (63.94 s-1), large emission cross section (6.0 × 10-21 cm2) and superior gain performance corresponding to the Dy3+: 6H13/2 → 6H15/2 transition were obtained. Moreover, the energy transfer mechanism was analyzed qualitatively, and it was found that the energy transfer from Yb3+: 2F5/2 to Dy3+: 6H5/2 level could be quite efficient. Hence, the results indicated that the prepared Dy3+/Yb3+ co-doped germanate glass could be a potential candidate for ∼3 μm mid-infrared solid state lasers.

Enhanced monolayer MoS2/InP heterostructure solar cells by graphene quantum dots

NASA Astrophysics Data System (ADS)

Wang, Peng; Lin, Shisheng; Ding, Guqiao; Li, Xiaoqiang; Wu, Zhiqian; Zhang, Shengjiao; Xu, Zhijuan; Xu, Sen; Lu, Yanghua; Xu, Wenli; Zheng, Zheyang

2016-04-01

We demonstrate significantly improved photovoltaic response of monolayer molybdenum disulfide (MoS2)/indium phosphide (InP) van der Waals heterostructure induced by graphene quantum dots (GQDs). Raman and photoluminescence measurements indicate that effective charge transfer takes place between GQDs and MoS2, which results in n-type doping of MoS2. The doping effect increases the barrier height at the MoS2/InP heterojunction, thus the averaged power conversion efficiency of MoS2/InP solar cells is improved from 2.1% to 4.1%. The light induced doping by GQD provides a feasible way for developing more efficient MoS2 based heterostructure solar cells.

Upconversion properties of Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses.

PubMed

Su, Fangning; Deng, Zaide

2006-01-01

The Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence of luminescence intensity on the ratio of Yb3+/Er3+ was studied, and the relationship between green upconversion luminescence intensity and Er3+ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses either when the Yb3+/Er3+ ratio is 25/1 and Er3+ concentration is 0.1 mol%, or when the Yb3+/Er3+ ratio is 10/1 and Er3+ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers.

Yb- and Er-doped fiber laser Q-switched with an optically uniform, broadband WS2 saturable absorber

PubMed Central

Zhang, M.; Hu, Guohua; Hu, Guoqing; Howe, R. C. T.; Chen, L.; Zheng, Z.; Hasan, T.

2015-01-01

We demonstrate a ytterbium (Yb) and an erbium (Er)-doped fiber laser Q-switched by a solution processed, optically uniform, few-layer tungsten disulfide saturable absorber (WS2-SA). Nonlinear optical absorption of the WS2-SA in the sub-bandgap region, attributed to the edge-induced states, is characterized by 3.1% and 4.9% modulation depths with 1.38 and 3.83 MW/cm2 saturation intensities at 1030 and 1558 nm, respectively. By integrating the optically uniform WS2-SA in the Yb- and Er-doped laser cavities, we obtain self-starting Q-switched pulses with microsecond duration and kilohertz repetition rates at 1030 and 1558 nm. Our work demonstrates broadband sub-bandgap saturable absorption of a single, solution processed WS2-SA, providing new potential efficacy for WS2 in ultrafast photonic applications. PMID:26657601

Enhanced Power Conversion Efficiency of Perovskite Solar Cells with an Up-Conversion Material of Er3+-Yb3+-Li+ Tri-doped TiO2

NASA Astrophysics Data System (ADS)

Zhang, Zhenlong; Qin, Jianqiang; Shi, Wenjia; Liu, Yanyan; Zhang, Yan; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2018-05-01

In this paper, Er3+-Yb3+-Li+ tri-doped TiO2 (UC-TiO2) was prepared by an addition of Li+ to Er3+-Yb3+ co-doped TiO2. The UC-TiO2 presented an enhanced up-conversion emission compared with Er3+-Yb3+ co-doped TiO2. The UC-TiO2 was applied to the perovskite solar cells. The power conversion efficiency (PCE) of the solar cells without UC-TiO2 was 14.0%, while the PCE of the solar cells with UC-TiO2 was increased to 16.5%, which presented an increase of 19%. The results suggested that UC-TiO2 is an effective up-conversion material. And this study provided a route to expand the spectral absorption of perovskite solar cells from visible light to near-infrared using up-conversion materials.

Enhanced Power Conversion Efficiency of Perovskite Solar Cells with an Up-Conversion Material of Er3+-Yb3+-Li+ Tri-doped TiO2.

PubMed

Zhang, Zhenlong; Qin, Jianqiang; Shi, Wenjia; Liu, Yanyan; Zhang, Yan; Liu, Yuefeng; Gao, Huiping; Mao, Yanli

2018-05-11

In this paper, Er 3+ -Yb 3+ -Li + tri-doped TiO 2 (UC-TiO 2 ) was prepared by an addition of Li + to Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 presented an enhanced up-conversion emission compared with Er 3+ -Yb 3+ co-doped TiO 2 . The UC-TiO 2 was applied to the perovskite solar cells. The power conversion efficiency (PCE) of the solar cells without UC-TiO 2 was 14.0%, while the PCE of the solar cells with UC-TiO 2 was increased to 16.5%, which presented an increase of 19%. The results suggested that UC-TiO 2 is an effective up-conversion material. And this study provided a route to expand the spectral absorption of perovskite solar cells from visible light to near-infrared using up-conversion materials.

Intense green and red upconversion emission of Er3+,Yb3+ co-doped CaZrO3 obtained by a solution combustion reaction

NASA Astrophysics Data System (ADS)

Singh, Vijay; Kumar Rai, Vineet; Haase, Markus

2012-09-01

CaZrO3 phosphors co-doped with Er3+ and Yb3+ ions have been prepared by the urea combustion route. The formation of the orthorhombic phase of CaZrO3 was confirmed by powder x-ray diffraction. The absorption in the 280-1800 nm region and excitation spectrum corresponding to the emission at 545 nm for CaZrO3:Er3+/CaZrO3:Er3+,Yb3+ phosphors have been recorded. Upon excitation at 978 nm, the material displays strong energy transfer upconversion emission in the green and red spectral regions. The upconversion emission of the CaZrO3:Er3+,Yb3+ co-doped material shows an increased red-to-green ratio, indicating cross relaxation between Er3+ ions.

Origin of near to middle infrared luminescence and energy transfer process of Er3+/Yb3+co-doped fluorotellurite glasses under different excitations

PubMed Central

Huang, Feifei; Liu, Xueqiang; Ma, Yaoyao; Kang, Shuai; Hu, Lili; Chen, Danping

2015-01-01

We report the near to middle infrared luminescence and energy transfer process of Er3+/Yb3+ co-doped fluorotellurite glasses under 980, 1550 and 800 nm excitations, respectively. Using a 980 nm laser diode pump, enhanced 1.5 and 2.7 μm emissions from Er3+:I13/2→4I15/2 and I11/2→4I13/2 transitions are observed, in which Yb3+ ions can increase pumping efficiency and be used as energy transfer donors. Meanwhile, Yb3+ can also be used as an acceptor and intensive upconversion luminescence of around 1000 nm is achieved from Er3+:I11/2→4I15/2 and Yb3+: F5/2→4F7/2 transitions using 1550 nm excitation. In addition, the luminescence properties and variation trendency by 800 nm excitation is similar to that using 1550 nm excitation. The optimum Er3+ and Yb3+ ion ratio is 1:1.5 and excess Yb3+ ions decrease energy transfer efficiency under the two pumpings. These results indicate that Er3+/Yb3+ co-doped fluorotellurite glasses are potential middle- infrared laser materials and may be used to increase the efficiency of the silicon solar cells. PMID:25648651

Unit cell parameters of wurtzite InP nanowires determined by x-ray diffraction.

PubMed

Kriegner, D; Wintersberger, E; Kawaguchi, K; Wallentin, J; Borgström, M T; Stangl, J

2011-10-21

High resolution x-ray diffraction is used to study the structural properties of the wurtzite polytype of InP nanowires. Wurtzite InP nanowires are grown by metal-organic vapor phase epitaxy using S-doping. From the evaluation of the Bragg peak position we determine the lattice parameters of the wurtzite InP nanowires. The unit cell dimensions are found to differ from the ones expected from geometric conversion of the cubic bulk InP lattice constant. The atomic distances along the c direction are increased whereas the atomic spacing in the a direction is reduced in comparison to the corresponding distances in the zinc-blende phase. Using core/shell nanowires with a thin core and thick nominally intrinsic shells we are able to determine the lattice parameters of wurtzite InP with a negligible influence of the S-doping due to the much larger volume in the shell. The determined material properties will enable the ab initio calculation of electronic and optical properties of wurtzite InP nanowires.

MW peak power Er/Yb-doped fiber femtosecond laser amplifier at 1.5 µm center wavelength

NASA Astrophysics Data System (ADS)

Han, Seongheum; Jang, Heesuk; Kim, Seungman; Kim, Young-Jin; Kim, Seung-Woo

2017-08-01

An erbium (Er)/ytterbium (Yb) co-doped double-clad fiber is configured to amplify single-mode pulses with a high average power of 10 W at a 1.5 µm center wavelength. The pulse duration at the exit of the Er/Yb fiber amplifier is measured to be ~440 fs after grating-based compression. The whole single-mode operation of the amplifier system permits the M 2-value of the output beam quality to be evaluated better than 1.05. By tuning the repetition rate from 100 MHz down to 600 kHz, the pulse peak power is scaled up to 19.1 MW to be the highest ever reported using an Er/Yb single-mode fiber. The proposed amplifier system is well suited for strong-power applications such as free-space LIDAR, non-thermal machining and medical surgery.

All-optical switching application based on optical nonlinearity of Yb(3+) doped aluminosilicate glass fiber with a long-period fiber gratings pair.

PubMed

Kim, Yune; Kim, Nam; Chung, Youngjoo; Paek, Un-Chul; Han, Won-Taek

2004-02-23

We propose a new fiber-type all-optical switching device based on the optical nonlinearity of Yb(3+) doped fiber and a long-period fiber gratings(LPG) pair. The all-optical ON-OFF switching with the continuous wave laser signal at ~1556nm in the LPG pair including the 25.5cm long Yb(3+) doped fiber was demonstrated up to ~200Hz upon pumping with the modulated square wave pulses at 976nm, where a full optical switching with the ~18dB extinction ratio was obtained at the launched pump power of ~35mW.

Several hundred kHz repetition rate nanosecond pulses amplification in Er-Yb co-doped fiber amplifier

NASA Astrophysics Data System (ADS)

Yang, Weiqiang; Yin, Ke; Zhang, Bin; Xue, Guanghui; Hou, Jing

2014-07-01

We have experimentally investigated several hundred kHz repetition rate 1,550-nm nanosecond pulses amplification in Er-Yb co-doped fiber amplifier (EYDFA). The experimental setup has three stage fiber amplifiers. At the output of the second stage EYDFA, Yb3+ ions induced amplified spontaneous emission (Yb-ASE) is not observed owing to the low pump power. In the third stage EYDFA, a simultaneously seeded 1,064-nm continuous-wave laser is used to control Yb-ASE. Without any additional 1,064-nm signal, significantly backward Yb-ASE which caused loss-induced heat accumulation at the input port of the pump combiner can be observed. The monitored temperature at the input port of the pump combiner rapidly grows from 30 to 80 °C when the pump power is turned from 20 to 32 W. When a 196-mW forward 1,064-nm laser is added, the monitored backward Yb-ASE power is significantly declined, and the monitored temperature is kept below 35 °C. But, the additional signal caused a large power fraction at 1,064 nm in the output laser. In our experiment at the maximum pump power of 48.5 W, the total output power is 20 W with ~6.4-W 1,550-nm pulsed laser and ~13-W 1,064-nm continuous-wave laser.

Synthesis of Er(III)/Yb(III)-doped BiF3 upconversion nanoparticles for use in optical thermometry.

PubMed

Du, Peng; Yu, Jae Su

2018-03-23

The authors describe an ethylene glycol assisted precipitation method for synthesis of Er(III)/Yb(III)-doped BiF 3 nanoparticles (NPs) at room temperature. Under 980-nm light irradiation, the NPs emit upconversion (UC) emission of Er(III) ions as a result of a two-photon absorption process. The temperature-dependent green emissions (peaking at 525 and 545 nm) are used to establish an unambiguous relationship between the ratio of fluorescence intensities and temperature. The NPs have a maximum sensitivity of 6.5 × 10 -3  K -1 at 619 K and can be applied over the 291-691 K temperature range. The results indicate that these NPs are a promising candidate for optical thermometry. Graphical abstract Schematic of the room-temperature preparation of Er(III)/Yb(III)-doped BiF 3 nanoparticles with strongly temperature-dependent upconversion emission.

A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

NASA Astrophysics Data System (ADS)

Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

2016-02-01

The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle

Ultraviolet and near-infrared luminescence of LaBO3:Ce3+,Yb3+

NASA Astrophysics Data System (ADS)

Wei, Heng-Wei; Shao, Li-Ming; Jiao, Huan; Jing, Xi-Ping

2018-01-01

Ce3+ or Yb3+ singly doped LaBO3 and Ce3+-Yb3+ co-doped LaBO3 were prepared by conventional solid state reactions at 1100 °C and their photoluminescence (PL) properties were investigated. The emission spectrum of LaBO3:Ce3+,Yb3+ contains both the Ce3+ ultraviolet (UV) emissions (355 nm and 380 nm) and the Yb3+ near infrared (NIR) emission (975 nm) when excited by the UV light at 270 nm. By using the data of the Ce3+ decay curves and the PL intensities of both Ce3+ and Yb3+, the energy transfer efficiency (η) from Ce3+ to Yb3+, the actual energy transfer efficiency (AE) and the quantum efficiency (Q) of the Yb3+ emission were calculated. In the Ce3+-Yb3+ co-doped LaBO3, Ce3+ can transfer its absorbed energy to Yb3+ efficiently (η can be over 60%), and Yb3+ shows the Q value over 50% when it accepts the energy from Ce3+, which results in the low AE value ∼30%. The energy transfer process from Ce3+ to Yb3+ may be understood by the charge transfer mechanism: Ce3+ + Yb3+ ↔ Ce4+ + Yb2+. Particularly the Ce3+-Yb3+ co-doped LaBO3 phosphor gives the emissions mainly in the UV range and the NIR range with a portion of visible emissions in eye-insensitive range. This unique property may be suitable for applications in anti-counterfeiting techniques and public security affairs.

Aptamer biosensor for Salmonella typhimurium detection based on luminescence energy transfer from Mn2 +-doped NaYF4:Yb, Tm upconverting nanoparticles to gold nanorods

NASA Astrophysics Data System (ADS)

Cheng, Keyi; Zhang, Jianguo; Zhang, Liping; Wang, Lun; Chen, Hongqi

2017-01-01

A highly sensitive luminescent bioassay for the detection of Salmonella typhimurium was fabricated using Mn2 +-doped NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) as the donor and gold nanorods (Au NRs) as the acceptor and utilizing an energy transfer (LET) system. Mn2 +-doped NaYF4:Yb,Tm UCNPs with a strong emission peak at 807 nm were obtained by changing the doped ion ratio. Carboxyl-terminated Mn2 +-doped NaYF4:Yb,Tm UCNPs were coupled with S. typhimurium aptamers, which were employed to capture and concentrate S. typhimurium. The electrostatic interactions shorten the distance between the negatively charged donor and the positively charged acceptor, which results in luminescence quenching. The added S. typhimurium leads to the restoration of luminescence due to the formation of UCNPs-aptamers-S. typhimurium, which repels the UCNPs-aptamers from the Au NRs. The LET system does not occur because of the nonexistence of the luminescence emission band of Mn2 +-doped NaYF4:Yb,Tm UCNPs, which had large spectral overlap with the absorption band of Au NRs. Under optimal conditions, the linear range of detecting S. typhimurium was 12 to 5 × 105 cfu/mL (R = 0.99). The limit of detection for S. typhimurium was as low as 11 cfu/mL in an aqueous buffer. The measurement of S. typhimurium in milk samples was satisfied in accordance with the plate-counting method, suggesting that the proposed method was of practical value in the application of food security.

Up-conversion white light of Tm 3+/Er 3+/Yb 3+ tri-doped CaF 2 phosphors

NASA Astrophysics Data System (ADS)

Cao, Chunyan; Qin, Weiping; Zhang, Jisen; Wang, Yan; Wang, Guofeng; Wei, Guodong; Zhu, Peifen; Wang, Lili; Jin, Longzhen

2008-03-01

Tm3+/Er3+/Yb3+ tri-doped CaF2 phosphors were synthesized using a hydrothermal method. The phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and up-conversion (UC) emission spectra. After annealing, the phosphors emitted white light under a 980 nm continuous wave diode laser (CW LD 2 W) excitation. As the excitation power density changed in the range of 20-260 W/cm2, the chromaticity coordinates of the UC light of the phosphor Ca0.885Tm0.005Er0.01Yb0.1F2 fell well in the white region of the 1931 CIE diagram. For the proportion of red, green and blue (RGB) in white light is strict, key factors for achieving UC white light, such as host materials, rare earth ions doping concentrations, annealing temperatures, as well as the excitation power densities, were investigated and discussed.

Effect of C6+ Ion Irradiation on structural and electrical properties of Yb and Eu doped Bi1.5 Zn0.92 Nb1.5 O6.92 pyrochlores

NASA Astrophysics Data System (ADS)

Yumak, Mehmet; Mergen, Ayhan; Qureshi, Anjum; Singh, N. L.

2015-03-01

Pyrochlore general formula of A2B2X7 where A and B are cations and X is an anion Pyrochlore compounds exhibit semiconductor, metallic or ionic conduction properties, depending on the doping, compositions/ substituting variety of cations and oxygen partial pressure. Ion beam irradiation can induce the structural disordering by mixing the cation and anion sublattices, therefore we aim to inevestigate effects of irradiation in pyrochlore compounds. In this study, Eu and Yb-doped Bi1.5Zn0.92Nb1.5O6.92 (Eu-BZN, Yb-BZN) Doping effect and single phase formation of Eu-BZN, Yb-BZN was characterized by X-ray diffraction technique (XRD). Radiation-induced effect of 85 MeV C6+ ions on Eu-BZN, Yb-BZN was studied by XRD, scanning electron microscopy (SEM) and temperature dependent dielectric measurements at different fluences. XRD results revealed that the ion beam-induced structural amorphization processes in Eu-BZN and Yb-BZN structures. Our results suggested that the ion beam irradiation induced the significant change in the temprature depndent dielectric properties of Eu-BZN and Yb-BZN pyrochlores due to the increased oxygen vacancies as a result of cation and anion disordering. Department of Metallurgical and Materials Eng., Marmara University, Istanbul-81040, Turkey.

Study of upconversion fluorescence property of novel Er3+/Yb3+ co-doped tellurite glasses.

PubMed

Xu, Tie-Feng; Li, Guang-Po; Nie, Qiu-Hua; Shen, Xiang

2006-06-01

Er3+/Yb3+ co-doped TeO2-B2O3-Nb2O5-ZnO (TBN) glasses were prepared. The absorption spectra and upconversion luminescence spectra of TBN glasses were measured and analyzed. The upconversion emission bands centered at 530, 546 and 658 nm were observed under the excitation at 975 nm, corresponding to the transitions of 2H11/2-->4I15/2, 4S3/2-->4I15/2 and 4F9/2-->4I15/2 respectively. The ratio of red emission to green emission increases with an increasing of Yb3+ ions concentration. According to the quadratic dependence on excitation power, the possible upconversion mechanisms and processes were discussed.

Investigations on the effects of the Stark splitting on the fluorescence behaviors in Yb3+-doped silicate, tellurite, germanate, and phosphate glasses

NASA Astrophysics Data System (ADS)

Zhang, Liaolin; Xia, Yu; Shen, Xiao; Yang, Runlan; Wei, Wei

2018-01-01

In this work, we systematically studied the spectroscopic characteristics of Yb3+ doped germanate, phosphate, silicate, and tellurite glasses. The emission peak beyond 976 nm showed irregular shift from 1001 nm to 1023 nm when Yb3+ in different glass matrices. It was associated with the Stark splitting of 2F7/2 and the emission intensities ratio between the transition from the lowest Stark splitting energy level of 2F5/2 to the Stark splitting energy levels of 2F7/2, e to b and that of e to d. Larger Stark splitting of 2F7/2 results in the red-shift of the near infrared emission band at room temperature and larger ratio results in the blue-shift of emission band. The fluorescence lifetimes of Yb3+ doped germanate, phosphate, silicate, and tellurite glasses were measured to be 0.94, 0.82, 1.51, and 0.66 ms, respectively. The fluorescence lifetime was associated with the reabsorption of Yb3+, which larger absorption cross section at the emission band results in larger reabsorption, then leads to the shorter near infrared fluorescence lifetime.

kW-level commercial Yb-doped aluminophosphosilicate ternary laser fiber

NASA Astrophysics Data System (ADS)

Sun, Shihao; Zhan, Huan; Li, Yuwei; Liu, Shuang; Jiang, Jiali; Peng, Kun; Wang, Yuying; Ni, Li; Wang, Xiaolong; Jiang, Lei; Yu, Juan; Liu, Gang; Lu, Pengfei; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

2018-03-01

Based on a master oscillator power amplifier configuration, laser performance of commercial Nufern-20/400-8M Ybdoped aluminophosphosilicate ternary laser fiber was investigated. Pumped by 976 nm laser diodes, 982 W laser output power was obtained with a slope efficiency of 84.9%. Spectrum of output was centered at 1066.56nm with 3dB bandwidth less than 0.32 nm, and the nonlinearity suppression ratio was more than 39dB. Beam quality of Mx2 and M2y were 1.55 and 1.75 at 982 W, respectively. The laser performance indicated that Nufern-20/400-8M Yb-doped aluminophosphosilicate ternary laser fiber is highly competitive for industry fiber laser use.

Influence of nanopowders sedimentation on characteristics of Yb-doped Y2O3 transparent ceramics

NASA Astrophysics Data System (ADS)

Aleksandrov, E. O.; Shitov, V. A.; Maksimov, R. N.; Basyrova, L. R.

2017-09-01

In this work we report on the effects induced by different conditions of nanopowders sedimentation on the microstructure features and optical properties of ytterbium-doped yttrium oxide (Yb:Y2O3) transparent ceramics sintered at 1780 °C for 20 h under a vacuum. The nanopowder of (Yb0.005Y0.995)2O3 co-doped with 5 at % ZrO2 was synthesized by laser ablation and used as the starting material for the fabrication of ceramics. The obtained nanoparticles were annealed at 1100 °C for 3 h in air in order to transform a metastable monoclinic phase into a main cubic phase. After sedimentation for 24 h in isopropyl alcohol the useful suspension was dried using a rotary evaporator operating at different temperatures and pressures. The use of lower evaporation temperature (37 °C) and higher vacuum level (10 mbar) lead to complete removal of organic species from the nanopowder and promote homogeneous densification of the powder compact. Under optimal treatment conditions the optical transmittance and the average content of the scattering centers were measured to be 77 % at a wavelength of 1080 nm and 0.25 ppm, respectively.

Cooperative and non-cooperative sensitization upconversion in lanthanide-doped LiYbF4 nanoparticles.

PubMed

Zou, Qilin; Huang, Ping; Zheng, Wei; You, Wenwu; Li, Renfu; Tu, Datao; Xu, Jin; Chen, Xueyuan

2017-05-18

Lanthanide (Ln 3+ )-doped upconversion nanoparticles (UCNPs) have attracted tremendous interest owing to their potential bioapplications. However, the intrinsic photophysics responsible for upconversion (UC) especially the cooperative sensitization UC (CSU) in colloidal Ln 3+ -doped UCNPs has remained untouched so far. Herein, we report a unique strategy for the synthesis of high-quality LiYbF 4 :Ln 3+ core-only and core/shell UCNPs with tunable particle sizes and shell thicknesses. Energy transfer UC from Er 3+ , Ho 3+ and Tm 3+ and CSU from Tb 3+ were comprehensively surveyed under 980 nm excitation. Through surface passivation, we achieved efficient non-cooperative sensitization UC with absolute UC quantum yields (QYs) of 3.36%, 0.69% and 0.81% for Er 3+ , Ho 3+ and Tm 3+ , respectively. Particularly, we for the first time quantitatively determined the CSU efficiency for Tb 3+ with an absolute QY of 0.0085% under excitation at a power density of 70 W cm -2 . By means of temperature-dependent steady-state and transient UC spectroscopy, we unraveled the dominant mechanisms of phonon-assisted cooperative energy transfer (T > 100 K) and sequential dimer ground-state absorption/excited-state absorption (T < 100 K) for the CSU process in LiYbF 4 :Tb 3+ UCNPs.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

PubMed Central

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-01-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 → 2I15/2 and 4S3/2 → 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K−1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

NASA Astrophysics Data System (ADS)

Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

2014-02-01

Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 --> 2I15/2 and 4S3/2 --> 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K-1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method.

PubMed

Gavrilović, Tamara V; Jovanović, Dragana J; Lojpur, Vesna; Dramićanin, Miroslav D

2014-02-27

Synthesis of Eu(3+)- and Er(3+)/Yb(3+)-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu(3+)-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er(3+)/Yb(3+)-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from (2)H11/2 → (2)I15/2 and (4)S3/2 → (4)I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K(-1), which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers.

Emission intensity of the λ = 1.54 μm line in ZnO films grown by magnetron sputtering, diffusion doped with Ce, Yb, Er

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mezdrogina, M. M., E-mail: margeret.m@mail.ioffe.ru; Eremenko, M. V.; Smirnov, A. N.

2015-08-15

The effect of the Er{sup 3+}-ion excitation type on the photoluminescence spectra of crystalline ZnO(ZnO〈Ce, Yb, Er〉) films is determined in the cases of resonant (λ = 532 nm, Er{sup 3+}-ion transition from {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} levels to {sup 4}I{sub 15/2}) and non-resonant (λ = 325 nm, in the region near the ZnO band-edge emission) excitation. It is shown that resonant excitation gives rise to lines with various emission intensities, characteristic of the Er{sup 3+}-ion intracenter 4f transition with λ = 1535 nm when doping crystalline ZnO films with three rare-earth ions (REIs, Ce, Yb, Er) ormore » with two impurities (Ce, Er) or (Er, Yb), independently of the measurement temperature (T = 83 and 300 K). The doping of crystalline ZnO films with rare-earth impurities (Ce, Yb, Er) leads to the efficient transfer of energy to REIs, a consequence of which is the intense emission of an Er{sup 3+} ion in the IR spectral region at λ{sub max} = 1535 nm. The kick-out diffusion mechanism is used upon the sequential introduction of impurities into semiconductor matrices and during the postgrowth annealing of the ZnO films under study. The crystalline ZnO films doped with Ce, Yb, Er also exhibit intense emission in the visible spectral region at room temperature, which makes them promising materials for optoelectronics.« less

Effect of silica surface coating on the luminescence lifetime and upconversion temperature sensing properties of semiconductor zinc oxide doped with gallium(III) and sensitized with rare earth ions Yb(III) and Tm(III).

PubMed

Li, Yuemei; Li, Yongmei; Wang, Rui; Zheng, Wei

2018-02-26

Optical sensing of temperature by measurement of the ratio of the intensities of the 700 nm emission and the 800 nm emission of Ga(III)-doped ZnO (GZO) nanoparticles (NPs) and of GZO NPs coated with a silica shell are demonstrated at 980 nm excitation. It is found that the relative sensitivity of SiO 2 @Yb/Tm/GZO is 6.2% K -1 at a temperature of 693 K. This is ~3.4 times higher than that of Yb/Tm/GZO NPs. Obviously, the SiO 2 shell structure decreases the rate of the nonradiative decay. The decay time of the 800 nm emission of the Yb/Tm/GZO NPs (15 mol% Ga; 7 mol% Yb; 0.5 mol% Tm) displays a biexponential decay with a dominant decay time of 148 μs and a second decay time of ~412 μs. The lifetime of the Yb/Tm/GZO NPs at 293 K, and of the SiO 2 @Yb/Tm/GZO NPs are ~412 μs. Both the Yb/Tm/GZO and SiO 2 @Yb/Tm/GZO can be used up to 693 K. These results indicate that the SiO 2 shell on the Yb/Tm/GZO is beneficial in terms of sensitivity and resolution. Graphical abstract The enhancement the decay time and thermal sensitivity in the SiO 2 @Yb/Tm/GZO shell@core structure have been studied compared to the Ga(III)-doped Yb/Tm-doped ZnO (Yb/Tm/GZO). The SiO 2 @Yb/Tm/GZO have good thermal accuracy up to 693 °C.

Upconversion luminescence in Er3+ doped and Er3+/Yb3+ codoped zirconia and hafnia nanocrystals excited at 980 nm

NASA Astrophysics Data System (ADS)

Gómez, Luis A.; Menezes, Leonardo de S.; de Araújo, Cid B.; Gonçalves, Rogeria R.; Ribeiro, Sidney J. L.; Messaddeq, Younes

2010-06-01

Frequency upconversion (UC) luminescence in nanocrystalline zirconia (ZrO2) and hafnia (HfO2) doped with Er3+ and Yb3+ was studied under continuous-wave excitation at 980 nm. Samples of ZrO2:Er3+, ZrO2:Er3+/Yb3+, and HfO2:Er3+/Yb3+ were prepared by the sol-gel technique and characterized using x-ray diffraction and electron microscopy. A study of the infrared-to-green and infrared-to-red UC processes was performed including the analysis of the spectral and the temporal behavior. The mechanisms contributing to the UC luminescence were identified as excited state absorption and energy transfer among rare-earth ions.

White up-conversion emission in Ho3+/Tm3+/Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals

NASA Astrophysics Data System (ADS)

Li, Chenxia; Xu, Shiqing; Ye, Rengguang; Deng, Degang; Hua, Youjie; Zhao, Shilong; Zhuang, Songlin

2011-04-01

Ho3+/Tm3+/Yb3+ tri-doped glass ceramics with white light emitting have been developed and demonstrated. Pumped by 980 nm laser diode (LD), intensive red, green and blue up-conversions (UC) were obtained. The green emission is assigned to Ho3+ ion and the blue emission is assigned to Tm3+ ion, whereas the red emission is the combination contribution of the Ho3+ and Tm3+ ions. The RGB intensities could be adjusted by tuning the rare-earth ion concentration and pump power intensity. Thus, multicolor of the luminescence, including perfect white light with CIE-X=0.329 and CIE-Y=0.342 in the 1931 CIE chromaticity diagram can be obtained in 0.15 Ho3+/0.2Tm3+/3Yb3+ tri-doped glass ceramics embedding BaF2 nanocrystals pumped by a single infrared laser diode source of 980 nm at 500 mW. The up-conversion luminescence mechanism of Yb3+ sensitize Ho3+ and Tm3+ ions and the energy transfer from Ho3+ to Tm3+ in oxy-fluoride silicate glass ceramics were analyzed.

Optical properties of Mg2+, Yb3+, and Ho3+ tri-doped LiNbO3 crystals

NASA Astrophysics Data System (ADS)

Dai, Li; Liu, Chun-Rui; Tan, Chao; Yan, Zhe-Hua; Xu, Yu-Heng

2017-04-01

A series of LiNbO3 crystals tri-doped with Mg{}2+, Yb{}3+, and Ho{}3+ are grown by the conventional Czochraski technique. The concentrations of Mg{}2+, Yb{}3+, and Ho{}3+ ions in Mg:Yb:Ho:LiNbO3 crystals are measured by using an inductively coupled plasma atomic emission spectrometry. The x-ray diffraction is proposed to determine the lattice constant and analyze the internal structure of the crystal. The light-induced scattering of Mg:Yb:Ho:LiNbO3 crystal is quantitatively described via the threshold effect of incident exposure energy flux. The exposure energy ({E}{{r}}) is calculated to discuss the optical damage resistance ability. The exposure energy of Mg(7 mol):Yb:Ho:LiNbO3 crystal is 709.17 J/cm2, approximately 425 times higher than that of the Mg(1 mol):Yb:Ho:LiNbO3 crystal in magnitude. The blue, red, and very intense green bands of Mg:Yb:Ho:LiNbO3 crystal are observed under the 980-nm laser excitation to evaluate the up-conversion emission properties. The dependence of the emission intensity on pumping power indicates that the up-conversion emission is a two-photon process. The up-conversion emission mechanism is discussed in detail. This study indicates that Mg:Yb:Ho:LiNbO3 crystal can be applied to the fabrication of new multifunctional photoluminescence devices. Project supported by the National Natural Science Foundation of China (Grant No. 51301055), the Youth Science Fund of Heilongjiang Province, China (Grant No. QC2015061), the Special Funds of Harbin Innovation Talents in Science and Technology Research, China (Grant No. 2015RQQXJ045 ), and the Science Funds for the Young Innovative Talents of Harbin University of Science and Technology, China (Grant No. 201501).

Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

NASA Astrophysics Data System (ADS)

Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

2016-01-01

We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 → 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ → Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 ± 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 μm with a maximum slope efficiency η = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 μm. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 μm is also demonstrated.

Blue upconversion in Yb3+/Tm3+ co-doped silica fiber based on glass phase-separation technology

NASA Astrophysics Data System (ADS)

Yang, Yu; Chu, Yingbo; Chen, Zhangru; Xing, Yingbin; Hu, Xionwei; Li, Haiqing; Peng, Jinggang; Dai, Nengli; Li, Jinyan; Yang, Luyun

2018-02-01

Yb3+/Tm3+ co-doped silica fiber was prepared successfully by glass phase-separation technology. The measured refractive index profile indicated that the active fiber core had an excellent uniformity. The highest emission intensity was obtained in a sample with a Yb3+ concentration of 0.3 mol/L and a Tm3+ concentration of 0.1 mol/L. Under the excitation at 976 nm, intense blue upconversion emission of Tm3+ at 474 nm was observed due to energy transfer from Yb3+ to Tm3+. A three-photon process was responsible for the blue emission. Due to re-absorption resulted from the Tm3+:3H6→1G4 transition, the blue emission peak was red-shifted. It is suggested that the fiber preparation technology based on glass phase-separation technology can be a potential candidate for preparing active fibers with large core or complex fiber structure.

Tuning the electronic hybridization in the heavy fermion cage compound YbFe2Zn20 with Cd doping

NASA Astrophysics Data System (ADS)

Cabrera-Baez, M.; Ribeiro, R. A.; Avila, M. A.

2016-09-01

The tuning of the electronic properties of heavy fermion compounds by chemical substitution provides excellent opportunities for further understanding the physics of hybridized ions in crystal lattices. Here we present an investigation on the effects of Cd doping in flux-grown single crystals of the complex intermetallic cage compound YbFe2Zn20, which has been described as a heavy fermion with a Sommerfeld coefficient of 535 mJ mol-1 · K-2. The substitution of Cd for Zn disturbs the system by expanding the unit cell and, in this case, the size of the Zn cages that surround the Yb and Fe. With an increasing amount of Cd, the hybridization between the Yb 4f electrons and the conduction electrons is weakened, as shown by a decrease in the Sommerfeld coefficient, which should be accompanied by a valence shift of the Yb3+ due to the negative chemical pressure effect. This scenario is also supported by the low temperature DC magnetic susceptibility, which is gradually suppressed and shows an increment of the Kondo temperature, based on a shift to higher temperatures of the characteristic broad susceptibility peak. Furthermore, the DC resistivity decreases with the isoelectronic substitution of Cd for Zn, contrary to expectations in an increasingly disordered system, and implying that the valence shift is not related to charge carrier doping. The combined results demonstrate the excellent complementarity between positive physical pressure and negative chemical pressure, and point to a rich playground for exploring the physics and chemistry of strongly correlated electron systems in the general family of Zn20 compounds, despite their structural complexity.

Mode-Selective Amplification in a Large Mode Area Yb-Doped Fiber Using a Photonic Lantern

DTIC Science & Technology

2016-05-15

in a few mode, double- clad Yb-doped large mode area (LMA) fiber, utilizing an all-fiber photonic lantern. Amplification to multi-watt output power is...that could enable dynamic spatial mode control in high power fiber lasers . © 2016 Optical Society of America OCIS codes: (060.2320) Fiber optics...amplifiers and oscillators; (060.2340) Fiber optics components. http://dx.doi.org/10.1364/OL.41.002157 The impressive growth experienced by fiber lasers and

Effect of cryogenic temperature on spectroscopic and laser properties of Er, Yb-doped potassium-lanthanum phosphate glass

NASA Astrophysics Data System (ADS)

Švejkar, Richard; Šulc, Jan; Němec, Michal; Jelínková, Helena; Nitsch, Karel; Cihlář, Antonín.; Král, Robert; Nejezchleb, Karel; Nikl, Martin

2017-05-01

Glass matrix doped with rare-earth ions is a promising laser active medium for high power laser systems. Due to amorphous structure of glasses the absorption and emission spectra lines are broader in comparison with crystalline materials thus pumping radiation can be absorbed efficiently, moreover much broader gain bandwidth is suitable for generation of ultra-short pulses. Another advantage of the glass matrix is the possibility to fabricate large volume ingots and simultaneously preservation of sufficient optical quality. The lower thermal conductivity of glasses can be compensated by geometry of the active medium for instance shaped into fibres or discs. We present temperature dependence of spectroscopic and laser properties of newly developed Er, Yb - doped potassium-lanthanum phosphate glass, which is appropriate for generation of radiation at 1.53 μm. The sample of Er,Yb:KLaP glassy mixture was cut into disc shape with dimensions of 2.5 mm (thickness) and 5 mm (diameter) and its faces were polished plan-parallelly without being anti-reflection coated. The temperature dependence of the transmission and emission spectra Er,Yb:KLaP together with the fluorescence decay time were measured the temperature range from 80 to 400 K. The fluorescence lifetime of manifold 4I13/2 (upper laser level) prolonged and the intensity of up-conversion radiation decreased with decreasing temperature. The longitudinal excitation of Er,Yb:KLaP was carried out by a fibre-coupled laser diode (pulse duration 2 ms, repetition rate 10 Hz, pump wavelength 969 nm). Laser resonator was hemispherical, with flat pumping mirror (HR @ 1.5 μm) and spherical output coupler (R = 98 % @ 1.5 - 1.6 μm). The Er,Yb:KLaP glass laser properties were investigated in the temperature range 80 - 300 K. The highest slope efficiency with respect to absorbed pumped power was 6.1 % at 80 K. The maximum output of peak amplitude power was 0.71 W at 80 K, i.e. 1.2 times higher than at 300 K. Tunability of laser

Cooperative upconversion luminescence in Tb{sup 3+}:Yb{sup 3+} co-doped Y{sub 2}SiO{sub 5} powders prepared by combustion synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br; Vieira, Simone A.; Guimarães, Renato B.

2014-03-15

Frequency upconversion (UC) luminescence via cooperative energy transfer (CET) process between pairs of Yb{sup 3+} and Tb{sup 3+} ions was investigated in Tb{sup 3+}:Yb{sup 3+}:Y{sub 2}SiO{sub 5} crystalline ceramic powders prepared by combustion synthesis. Surface morphology and structure of the powders were investigated by scanning electronic microscopy and X-ray powder diffraction. Photoluminescence experiments were performed in Tb{sup 3+}-singly doped samples using ultraviolet light (λ=255 nm) and in Tb{sup 3+}:Yb{sup 3+} co-doped samples using a near-infrared (NIR) diode laser (λ=975 nm). Upon excitation with the NIR diode laser, UC luminescence with an intense emission band centered at ∼549 nm, corresponding tomore » the 4f intraband {sup 5}D{sub 4}→{sup 7}F{sub 5} transition of Tb{sup 3+}, along with less intense emission bands at ∼490, ∼590 and ∼620 nm, corresponding to other {sup 5}D{sub 4}→{sup 7}F{sub J} transitions, was detected. The CET rate was estimated by analyzing the dynamics of UC luminescence with rate equations model of the electronic populations. -- Graphical Abstract: Left: Cooperative upconversion luminescence spectra of three powder samples prepared by combustion synthesis. Right: The SEM image of the powder showing that it consists of agglomerated flake-like shaped particles of various sizes. Full scale bar is 20 μm. Highlights: • Yttrium orthosilicate (Y{sub 2}SiO{sub 5}) powders were prepared by combustion synthesis. • Cooperative upconversion is observed for the first time in Tb{sup 3+}–Yb{sup 3+} doped Y{sub 2}SiO{sub 5}. • Energy transfer and back-transfer rates between Tb{sup 3+} and Yb{sup 3+} pairs were estimated.« less

Systems and methods for advanced ultra-high-performance InP solar cells

DOEpatents

Wanlass, Mark

2017-03-07

Systems and Methods for Advanced Ultra-High-Performance InP Solar Cells are provided. In one embodiment, an InP photovoltaic device comprises: a p-n junction absorber layer comprising at least one InP layer; a front surface confinement layer; and a back surface confinement layer; wherein either the front surface confinement layer or the back surface confinement layer forms part of a High-Low (HL) doping architecture; and wherein either the front surface confinement layer or the back surface confinement layer forms part of a heterointerface system architecture.

Study of surface passivation as a function of InP closed-ampoule solar cell fabrication processing variables

NASA Technical Reports Server (NTRS)

Faur, Mircea; Faur, Maria; Jenkins, Phillip; Goradia, Manju; Goradia, Chandra; Bailey, Sheila; Weinberg, Irving; Jayne, Douglas

1990-01-01

The effects of various surface preparation procedures, including chemical treatment and anodic or chemical oxidation, closed-ampoule diffusion conditions, and post-diffusion surface preparation and annealing conditions, on the passivating properties of InP have been investigated in order to optimize the fabrication procedures of n(+)p InP solar cells made by closed-ampoule diffusion of sulfur into p-type InP. The InP substrates used were p-type Cd-doped to a level of 1.7 x 10 to the 16th/cu cm, Zn-doped to levels of 2.2 x 10 to the 16th and 1.2 x 10 to the 18th/cu cm, and n-type S-doped to 4.4 x 10 to the 18th/cu cm. The passivating properties have been evaluated from photoluminescence (PL) and conductance-voltage (G-V) data. Good agreement was found between the level of surface passivation and the composition of different surface layers as revealed by X-ray photoelectron spectroscopy (XPS) analysis.

Identification of parasitic losses in Yb:YLF and prospects for optical refrigeration down to 80K.

PubMed

Melgaard, Seth; Seletskiy, Denis; Polyak, Victor; Asmerom, Yemane; Sheik-Bahae, Mansoor

2014-04-07

Systematic study of Yb doping concentration in the Yb:YLF cryocoolers by means of optical and mass spectroscopies has identified iron ions as the main source of the background absorption. Parasitic absorption was observed to decrease with Yb doping, resulting in optical cooling of a 10% Yb:YLF sample to 114K ± 1K, with room temperature cooling power of 750 mW and calculated minimum achievable temperature of 93 K.

1-MHz high power femtosecond Yb-doped fiber chirped-pulse amplifier

NASA Astrophysics Data System (ADS)

Hu, Zhong-Qi; Yang, Pei-Long; Teng, Hao; Zhu, Jiang-Feng; Wei, Zhi-Yi

2018-01-01

A practical femtosecond polarization-maintaining Yb-doped fiber amplifier enabling 153 fs transform-limited pulse duration with 32 μJ pulse energy at 1 MHz repetition rate corresponding to a peak power of 0.21 GW is demonstrated. The laser system based on chirped-pulse amplification (CPA) technique is seeded by a dispersion managed, nonlinear polarization evolution (NPE) mode-locked oscillator with spectrum bandwidth of 31 nm at 1040 nm and amplified by three fiber pre-amplifying stages and a rod type fiber main amplifying stage. The laser works with beam quality of M2 of 1.3 and power stability of 0.63% (root mean square, RMS) over 24 hours will be stable sources for industrial micromachining, medical therapy and scientific research.

Nd³⁺-Yb³⁺ doped powder for near-infrared optical temperature sensing.

PubMed

Rakov, Nikifor; Maciel, Glauco S

2014-07-01

Er³⁺ doped powders are generally used for fluorescence-based temperature sensing application when near-infrared lasers are the excitation sources of choice. The fluorescence of Er³⁺ is produced by nonlinear (upconversion) processes, which generate strong internal heat. Lowering the excitation power causes drastic reduction of the fluorescence signal, and as a consequence the sensor applicability of Er³⁺ doped powders becomes compromised. Here we propose the use of the downconverted fluorescence of Yb³⁺ produced by efficient energy transfer from Nd³⁺ as an alternative temperature sensing system. Our results are presented for yttrium silicate powders prepared by combustion synthesis.

Mode instability in a Yb-doped stretched core fiber

NASA Astrophysics Data System (ADS)

Xia, N.; Yoo, S.

2017-02-01

In this work we present the theoretical study of transverse mode instability (TMI) in ytterbium (Yb)-doped rectangular core fibers with different core aspect ratios using the fast Fourier transform (FFT) beam propagation method (BPM). As expected, the rectangular core fiber with larger aspect ratio (AR.) offers more efficient heat dissipation than a circular core fiber. However, it is found that the rectangular core fiber does not benefit from the better heat dissipation to suppress the TMI when compared to the circular core counterpart. The temperature building in the rectangular core fiber decreases by up to 24.6% with a 10:1 aspect ratio core, while threshold pump power drops by up to 38.3% when compared with a circular core fiber with the same core area. Our study reveals that a smaller effective refractive index difference between modes and a weaker gain saturation effect compensate the thermal advantage from more efficient heat dissipation.

Upconversion luminescence of Er3+/Yb3+ doped Sr5(PO4)3OH phosphor powders

NASA Astrophysics Data System (ADS)

Mokoena, P. P.; Swart, H. C.; Ntwaeaborwa, O. M.

2018-04-01

Sr5(PO4)3OH co-doped with Er3+and Yb3+ powder phosphors were synthesized by urea combustion method. The crystal structure was analyzed using X-ray diffraction (XRD). Particle morphology was analyzed using a Jeol JSM 7800F thermal field emission scanning electron microscope (FE-SEM) and the chemical composition analysis was carried out using an Oxford Instruments AzTEC energy dispersive spectrometer (EDS) attached to the FE-SEM. Upconversion emission was measured by using a FLS980 Spectrometer equipped with a 980 nm NIR laser as the excitation source, and a photomultiplier (PMT) detector. The XRD data of the Sr5(PO4)3OH powder exhibited characteristic diffraction patterns of the hexagonal structure referenced in the standard JCPDS card number 00-033-1348. The sharp peaks revealed the formation of crystalline Sr5(PO4)3OH. The powders were made up of hexagonal nanospheres. The enhanced red emission due to the 4F9/2 → 4I15/2 transitions of Er3+ was observed and was attributed to up conversion (UC) energy transfer from Yb3+. The upconversion energy transfer mechanism from Yb3+ to Er3+ is discussed.

Biocompatible Er, Yb co-doped fluoroapatite upconversion nanoparticles for imaging applications

NASA Astrophysics Data System (ADS)

Anjana, R.; K. M., Kurias; M. K., Jayaraj

2017-08-01

Upconversion luminescence, visible emission on infra red (IR) excitation was achieved in a biocompatible material, fluoroapatite. Fluoroapatite crystals are well known biomaterials, which is a component of tooth enamel. Also it can be considered as an excellent host material for lanthanide doping since the ionic radii of lanthanide is similar to that of calcium ion(Ca2+) hence successful incorporation of dopants within the lattice is possible. Erbium (Er), Ytterbium (Yb) co-doped fluorapatite (FAp) nanoparticles were prepared by precipitation method. The particles show intense visible emission when excited with 980 nm laser. Since upconversion luminescence is a multiphoton process the excitation power dependence on emission will give number of photons involved in the emission of single photon. Excitation power dependence studies show that two photons are involved in the emission of single photons. The value of slope was different for different emission peak because of the difference in intermediate energy level involved. The crystal structure and morphology of the particle were determined using X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM). These particles with surface functionalisation can be used for live cell imaging.

Synthetic and spectroscopic studies of vanadate glaserites I: Upconversion studies of doubly co-doped (Er, Tm, or Ho):Yb:K{sub 3}Y(VO{sub 4}){sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kimani, Martin M., E-mail: kimani@g.clemson.edu; Chen, Hongyu, E-mail: hongyuc@g.clemson.edu; McMillen, Colin D., E-mail: cmcmill@g.clemson.edu

2015-03-15

The synthesis and upconversion properties of trigonal glaserite-type K{sub 3}Y(VO{sub 4}){sub 2} co-doped with Er{sup 3+}/Yb{sup 3+}, Ho{sup 3+}/Yb{sup 3+}, or Tm{sup 3+}/Yb{sup 3+} were studied. Powder samples were synthesized by solid state reactions at 1000 °C for 48 h, while well-formed hexagonal single crystals of the same were grown hydrothermally using 10 M K{sub 2}CO{sub 3} at 560–650 °C. Infrared-to-visible upconversion by Er{sup 3+}/Yb{sup 3+}, Ho{sup 3+}/Yb{sup 3+}, or Tm{sup 3+}/Yb{sup 3+} codoped-K{sub 3}Y(VO{sub 4}){sub 2} glaserite powder and single crystals was observed, and the upconversion spectral properties were studied as a function of different Er{sup 3+}, Tm{sup 3+},more » Ho{sup 3+}, and Yb{sup 3+} ion concentrations. The process is observed under 980 nm laser diode excitation and leads to strong green (552 nm) and red (659 nm) emission for Er{sup 3+}/Yb{sup 3+}, green (549 nm) and red (664 nm) emission for Ho{sup 3+}/Yb{sup 3+}, and blue (475 nm) and red (647 nm) emission for Tm{sup 3+}/Yb{sup 3+}. The main mechanism that allows for up-conversion is attributed the energy transfer among Yb{sup 3+} and the various Er{sup 3+}/Ho{sup 3+}/Tm{sup 3+} ions in excited states. These results illustrate the large potential of co-doped alkali double vanadates for photonic applications involving optoelectronics devices. - Graphical abstract: Synthesis and upconversion in vanadate glaserites. - Highlights: • K{sub 3}Y(VO{sub 4}){sub 2} codoped with Er, Tm, or Ho:Yb were synthesized via solid-state and hydrothermal routes. • Upconversion properties are investigated. • The codoped compounds revealed efficient infrared-to-visible upconversion. • The presented compounds are potential host for solid state lighting.« less

Forward to cryogenic temperature: laser cooling of Yb: LuLiF crystal

NASA Astrophysics Data System (ADS)

Zhong, Biao; Luo, Hao; Lei, Yongqing; Shi, Yanling; Yin, Jianping

2017-06-01

The high quality Yb-doped fluoride crystals have broad prospects for optical refrigeration. We have laser cooled the Yb:LuLiF crystal to a temperature below the limit of current thermoelectric coolers ( 180 K). The 5% Yb:LuLiF crystal sample has a geometry of 2 mm×2 mm×5 mm and was supported by two fibers of 200 μm in diameter. They were placed in a 2×10-4 Pa vacuum chamber with an environment temperature of 294.5 K. The 1019 nm CW laser of power 38.7 W was adopted to irradiate the sample. The temperature of the sample was measured utilizing the DLT methods. After 20 minutes of laser irradiation, the 5% Yb:LuLiF crystal sample was cooled down to 182.4 K. By further optimizing experimental conditions and increasing the doped Yb concentration, the Yb:LuLiF crystal might be optically cooled below the cryogenic temperature of 123K in the near future.

Up-conversion green emission of Yb3+/Er3+ ions doped YVO4 nanocrystals obtained via modified Pechini's method

NASA Astrophysics Data System (ADS)

Szczeszak, Agata; Runowski, Marcin; Wiglusz, Rafal J.; Grzyb, Tomasz; Lis, Stefan

2017-12-01

A series of lanthanide doped yttrium vanadates were prepared by Pechini's method (sol-gel process). The as-prepared precursors, in the presence of citric acid, were calcined in the temperature range of 600-900 °C. The obtained products were composed of small nanoparticles, in the size range of 20-50 nm, depending on the annealing temperature, exhibiting a bright green up-conversion emission, under NIR laser irradiation, and emission lifetimes in the range of 4.7-18.3 μs. Their structural, morphological and spectroscopic properties were investigated in detail by XRD, HR-TEM including FFT analysis, EDX and spectroscopic techniques (emission, power dependence and emission kinetics). The luminescence quenching phenomenon, manifested in a decrease of up-conversion intensity and shortening of emission lifetime, was observed with increasing of the Yb3+ ion concentration and decreasing the particle size. The optimal concentration of the Yb3+ ions was found to be 15 mol% (YVO4: Yb3+ 15 mol%, Er3+ 2 mol%).

Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupke, William F.; Payne, Stephen A.; Chase, Lloyd L.

An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupke, W.F.; Payne, S.A.; Chase, L.L.

An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca{sub 5}(PO{sub 4}){sub 3}F) or Yb:FAP, or ytterbium doped crystals structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

Formation Mechanism, Structural, and Upconversion Properties of Alkaline Rare-Earth Fluoride Nanocrystals Doped With Yb3+/Er3+ Ions.

PubMed

Grzyb, Tomasz; Przybylska, Dominika

2018-06-04

Ultrasmall (9-30 nm) Yb 3+ /Er 3+ -doped, upconverting alkaline rare-earth fluorides that are promising for future applications were synthesized by the microwave-assisted hydrothermal method. The formation mechanism was proposed, indicating the influence of the stability of metal ions complexes with ethylenediaminetetraacetic acid on the composition of the product and tendency to form M 2 REF 7 (M 0.67 RE 0.33 F 2.33 ) cubic compounds in the M-RE-F systems. Their physicochemical properties (structure, morphology, and spectroscopic properties) are compared and discussed. The obtained nanoparticles exhibited emission of light in the visible spectra under excitation by 976 nm laser radiation. Excitation and emission spectra, luminescence decays, laser energy dependencies, and upconversion quantum yields were measured to determine the spectroscopic properties of prepared materials. The Yb 3+ /Er 3+ pair of ions used as dopants was responsible for an intense yellowish-green emission. The upconversion quantum yields determined for the first time for M 2 REF 7 -based materials were 0.0192 ± 0.001% and 0.0176 ± 0.001% for Sr 2 LuF 7 :Yb 3+ ,Er 3+ and Ba 2 LuF 7 :Yb 3+ ,Er 3+ respectively, the two best emitting samples. These results indicated the prepared materials are good and promising alternatives for the most studied NaYF 4 :Yb 3+ ,Er 3+ nanoparticles.

Quadratic general rotary unitized design for doping concentrations and up-conversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Jiashi, E-mail: sunjs@dlmu.edu.cn; Shi, Linlin; Li, Shuwei

Highlights: • NaLa(MoO4)2: Er3+/Yb3+ phosphor is synthesized by solid state method. • QGRUD is first applied to the codoping concentration option. • Optimized phosphor presents more stable UC emissions than the commercial phosphor. - Abstract: It is still a great challenge that designing proper codoping concentrations of rare earth ions for achieving intensest expected emission from the studied phosphor. In this work, the quadratic general rotary unitized design (QGRUD) was introduced into the codoping concentration option of NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor for upconversion (UC) applications, and the optimum doping concentrations of Er{sup 3+} and Yb{sup 3+} formore » achieving maximum UC luminescence intensity, which is close to commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor, were obtained. The two-photon process was assigned to the green UC emissions in the optimized NaLa(MoO{sub 4}){sub 2}: Er{sup 3+}/Yb{sup 3+} phosphor. It was also demonstrated that the optimized phosphor presented more stable upconversion emissions than the commercial NaYF{sub 4}:Er{sup 3+}/Yb{sup 3+} phosphor.« less

Sol-Gel Derived Active Material for Yb Thin-Disk Lasers

PubMed Central

Almeida, Rui M.; Ribeiro, Tiago

2017-01-01

A ytterbium doped active material for thin-disk laser was developed based on aluminosilicate and phosphosilicate glass matrices containing up to 30 mol% YbO1.5. Thick films and bulk samples were prepared by sol-gel processing. The structural nature of the base material was assessed by X-ray diffraction and Raman spectroscopy and the film morphology was evidenced by scanning electron microscopy. The photoluminescence (PL) properties of different compositions, including emission spectra and lifetimes, were also studied. Er3+ was used as an internal reference to compare the intensities of the Yb3+ PL peaks at ~ 1020 nm. The Yb3+ PL lifetimes were found to vary between 1.0 and 0.5 ms when the Yb concentration increased from 3 to 30 mol%. Based on a figure of merit, the best active material selected was the aluminosilicate glass composition 71 SiO2-14 AlO1.5-15 YbO1.5 (in mol%). An active disk, ~ 36 μm thick, consisting of a Bragg mirror, an aluminosilicate layer doped with 15 mol% Yb and an anti-reflective coating, was fabricated. PMID:28869488

Optical properties of Sulfur doped InP single crystals

NASA Astrophysics Data System (ADS)

El-Nahass, M. M.; Youssef, S. B.; Ali, H. A. M.

2014-05-01

Optical properties of InP:S single crystals were investigated using spectrophotometric measurements in the spectral range of 200-2500 nm. The absorption coefficient and refractive index were calculated. It was found that InP:S crystals exhibit allowed and forbidden direct transitions with energy gaps of 1.578 and 1.528 eV, respectively. Analysis of the refractive index in the normal dispersion region was discussed in terms of the single oscillator model. Some optical dispersion parameters namely: the dispersion energy (Ed), single oscillator energy (Eo), high frequency dielectric constant (ɛ∞), and lattice dielectric constant (ɛL) were determined. The volume and the surface energy loss functions (VELF & SELF) were estimated. Also, the real and imaginary parts of the complex conductivity were calculated.

Ultralow-threshold Yb(3+):SiO(2) glass laser fabricated by the solgel process.

PubMed

Ostby, Eric P; Yang, Lan; Vahala, Kerry J

2007-09-15

A Yb-doped silica microcavity laser on a silicon chip is fabricated from a solgel thin film. The high-Q micro-toroid cavity, which has a finesse of 10,000, is evanescently coupled to an optical fiber taper. We report a threshold of 1.8 microW absorbed power that is, to the best of our knowledge, the lowest published threshold to date for any Yb-doped laser. The effect of Yb(3+) concentration on laser threshold is experimentally quantified.

Heavily Yb-doped phosphate large-mode area all-solid photonic crystal fiber operating at 990 nm

NASA Astrophysics Data System (ADS)

Wang, Longfei; He, Dongbing; Feng, Suya; Yu, Chunlei; Hu, Lili; Qiu, Jianrong; Chen, Danping

2015-07-01

We demonstrate, for the first time to our knowledge, a 16 wt.% Yb-doped phosphate large-mode area all-solid photonic crystal fiber (AS-PCF) laser operating at 990 nm. By carefully tailoring the absorption and emission properties of the active glass and designing the structure of AS-PCF, the excitation of the 990 nm laser and the depression of the laser above 1 µm can be easily realized even without any wavelength-selective optics. The single-mode behavior of PCF with a 35 µm doped core, the largest core diameter of approximately 1 µm in phosphate fiber, is theoretically investigated by finite-difference time-domain method and experimentally confirmed.

Growth and Spectral Assessment of Yb3+-Doped KBaGd(MoO4)3 Crystal: A Candidate for Ultrashort Pulse and Tunable Lasers

PubMed Central

Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Wang, Guofu

2013-01-01

In order to explore new more powerful ultrashort pulse laser and tunable laser for diode-pumping, this paper reports the growth and spectral assessment of Yb3+-doped KBaGd(MoO4)3 crystal. An Yb3+:KBaGd(MoO4)3 crystal with dimensions of 50×40×9 mm3 was grown by the TSSG method from the K2Mo2O7 flux. The investigated spectral properties indicated that Yb3+:KBaGd(MoO4)3 crystal exhibits broad absorption and emission bands, except the large emission and gain cross-sections. This feature of the broad absorption and emission bands is not only suitable for the diode pumping, but also for the production of ultrashort pulses and tunability. Therefore, Yb3+:KBaGd(MoO4)3 crystal can be regarded as a candidate for the ultrashort pulse and tunable lasers. PMID:23349892

Growth and spectral assessment of Yb(3+)-doped KBaGd(MoO4)3 crystal: a candidate for ultrashort pulse and tunable lasers.

PubMed

Yu, Yi; Huang, Yisheng; Zhang, Lizhen; Lin, Zhoubin; Wang, Guofu

2013-01-01

In order to explore new more powerful ultrashort pulse laser and tunable laser for diode-pumping, this paper reports the growth and spectral assessment of Yb(3+)-doped KBaGd(MoO(4))(3) crystal. An Yb(3+):KBaGd(MoO(4))(3) crystal with dimensions of 50×40×9 mm(3) was grown by the TSSG method from the K(2)Mo(2)O(7) flux. The investigated spectral properties indicated that Yb(3+):KBaGd(MoO(4))(3) crystal exhibits broad absorption and emission bands, except the large emission and gain cross-sections. This feature of the broad absorption and emission bands is not only suitable for the diode pumping, but also for the production of ultrashort pulses and tunability. Therefore, Yb(3+):KBaGd(MoO(4))(3) crystal can be regarded as a candidate for the ultrashort pulse and tunable lasers.

Better Ohmic Contacts For InP Semiconductor Devices

NASA Technical Reports Server (NTRS)

Weizer, Victor G.; Fatemi, Navid S.

1995-01-01

Four design modifications enable fabrication of improved ohmic contacts on InP-based semiconductor devices. First modification consists of insertion of layer of gold phosphide between n-doped InP and metal or other overlayer of contact material. Second, includes first modification plus use of particular metal overlayer to achieve very low contact resistivities. Third, also involves deposition of Au(2)P(3) interlayer; in addition, refractory metal (W or Ta) deposited to form contact overlayer. In fourth, contact layer of Auln alloy deposited directly on InP. Improved contacts exhibit low electrical resistances and fabricated without exposing devices to destructive predeposition or postdeposition treatments.

Cladding pumped Yb-doped HOM power amplifier with high gain

NASA Astrophysics Data System (ADS)

Abedin, Kazi S.; Ahmad, Raja; DeSantolo, Anthony M.; Nicholson, Jeffrey W.; Westbrook, Paul S.; Headley, Clifford; DiGiovanni, David J.

2018-02-01

Higher-order mode (HOM) fibers have been engineered to allow propagation of linearly polarized symmetric modes LP0,N in a robust way. Compared with the fundamental mode LP(0,1), HOMs exhibits an effective area that can be larger by over two order magnitude, and thus propagating light in these modes could greatly suppress the effect of nonlinear effects. HOM fibers could also be doped with rare earth ions in order to amplify light propagating in these modes, which offers the enormous potential for generating high-intensity pulses. Excitation of HOM gain fiber using cladding pumping with multimode pump source is attractive for ytterbium based amplifiers, because of the availability of low-cost multimode pump diodes in the 975nm wavelength range. One problem associated with cladding pumping which leads to excitation of the large doped core (over 100 μm diameter) is that it could result in a large amount of amplifiedspontaneous- emission (ASE) noise, particularly when the input signal is weak. Optimization of amplifier design is critical in order to suppress ASE and achieve high gain and pump-to-signal conversion efficiency. We conducted numerical modeling of a cladding pumped HOM-amplifier, which revealed that this problem could be mitigated by using a relatively long gain-fiber that allowed reabsorption of the forward propagating ASE resulting in a further amplification of the signal. We demonstrate efficient amplification of a LP0,10 mode with an effective area 3140μm2 in an Yb-doped HOM amplifier cladding pumped at 975nm. We have successfully obtained a 20.2dB gain for 0.95 W 1064 nm input seed signal to more than 105W.

Yb3+ sensitized Tm3+ upconversion in tellurite lead oxide glass.

PubMed

Mohanty, Deepak Kumar; Rai, Vineet Kumar; Dwivedi, Y

2012-04-01

Triply ionized thulium/thulium--ytterbium doped/codoped TeO2-Pb3O4 (TPO) glasses have been fabricated by classical quenching method. The upconversion emission spectra in the Tm3+/Tm3+-Yb3+ doped/codoped glasses upon excitation with a diode laser lasing at ∼980 nm has been studied. Effect of the addition of the Yb3+ on the upconversion emission intensity in the visible and near infrared regions of the Tm3+ doped in TPO glass has been studied and the processes involved explored. Copyright © 2011 Elsevier B.V. All rights reserved.

Spectral and laser properties of Er3+/Yb3+/Ce3+ tri-doped Ca3NbGa3Si2O14 crystal at 1.55 µm

NASA Astrophysics Data System (ADS)

Gong, Guoliang; Chen, Yujin; Lin, Yanfu; Huang, Jianhua; Gong, Xinghong; Luo, Zundu; Huang, Yidong

2018-04-01

An Er3+/Yb3+/Ce3+ tri-doped Ca3NbGa3Si2O14 (CNGS) crystal was grown by the Czochralski method. Spectral properties of the crystal, including the polarized absorption and fluorescence spectra, the fluorescence decay, as well as the energy transfer efficiency from Yb3+ to Er3+ were investigated in detail. End-pumped by a 976 nm diode laser, a 1556 nm continuous-wave laser with a maximum output power of 202 mW and a slope efficiency of 11.4% was achieved in the Er,Yb,Ce:CNGS crystal. The results indicate the Er,Yb,Ce:CNGS crystal is a promising 1.55 µm laser gain medium.

Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krupke, W.F.; Payne, S.A.; Chase, L.L.

An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

DOEpatents

Krupke, W.F.; Payne, S.A.; Chase, L.L.; Smith, L.K.

1994-01-18

An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises ytterbium doped apatite (Yb:Ca[sub 5](PO[sub 4])[sub 3]F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode. 9 figures.

Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting in Tb and Yb co-doped glass containing Ag nanoparticles

NASA Astrophysics Data System (ADS)

Pan, Z.; Sekar, G.; Akrobetu, R.; Mu, R.; Morgan, S. H.

2011-10-01

Tb, Yb, and Ag co-doped glass nano-composites were synthesized in a lithium-lanthanum-aluminosilicate glass matrix (LLAS) by a melt-quench technique. Ag nanoparticles (NPs) were formed in the glass matrix and confirmed by optical absorption and transmission electron microscopy (TEM). Plasmon enhanced luminescence was observed. Cooperative infrared to visible upconversion and visible to near-infrared quantum cutting were studied for samples with different thermal annealing times. Because the Yb3+ emission at 940 - 1020 nm is matched well with the band gap of crystalline Si, the quantum cutting effect may have its potential application in silicon-based solar cells.

Spectroscopic and laser cooling results on Yb3+-doped BaY2F8 single crystal

NASA Astrophysics Data System (ADS)

Bigotta, Stefano; Parisi, Daniela; Bonelli, Lucia; Toncelli, Alessandra; Tonelli, Mauro; Di Lieto, Alberto

2006-07-01

Anti-Stokes cooling has been observed in an Yb3+-doped BaY2F8 single crystal. Single crystals have been grown by the Czochralski technique. The absorption spectra and the emission properties have been measured at room temperature and at 10K. The energy positions of the Stark sublevels of the ground and the excited state manifolds have been determined and separated from the vibronic substructure. The intrinsic decay time of the F5/22 level has been measured taking care of avoiding the effect of multiple reabsorption processes. The theoretical and experimental cooling efficiencies of Yb:BaY2F8 are evaluated and compared with respect to those of the most frequently investigated materials for laser cooling. A temperature drop of almost 4K was measured by pumping the crystal with 3W of laser radiation at ˜1025nm in single pass configuration with a cooling efficiency of ˜3%.

Effect of Yb doping on the refractive index and thermo-optic coefficient of YVO₄ single crystals.

PubMed

Soharab, M; Bhaumik, Indranil; Bhatt, R; Saxena, A; Karnal, A K; Gupta, P K

2017-02-20

Single crystals of YVO₄ with different doping concentrations of Yb (1.5, 3.0, 8.0, and 15.0 at. %) and with good crystalline quality (FWHM ∼43-55 arc sec of rocking curve) were grown by the optical floating zone technique. Refractive index measurements were carried out at four wavelengths as a function of temperature. The measurements show that as the doping concentration of Yb is increased, the refractive index varies marginally for n_e whereas there is a significant change in the value of n_o. The thermo-optic coefficient (dn/dT) was found to be positive with a value ∼10^-5/°C, which is 1 order higher than that for the undoped YVO₄ crystal. The thermo-optic coefficient is higher for n_e compared to that of n_o. Also, a set of relations describing the wavelength dependence of the thermo-optic coefficient were established that are useful for calculating the thermo-optic coefficient at any temperature in the range 30°C-150°C and at any wavelength in the range 532-1551 nm.

Structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor, synthesized using the solid-state reaction method, and its luminescence behavior.

PubMed

Tamrakar, Raunak Kumar; Bisen, D P; Brahme, Nameeta

2016-02-01

We report the synthesis and structural characterization of Er(3+),Yb(3+)-doped Gd2O3 phosphor. The sample was prepared using the conventional solid-state reaction method, which is the most suitable method for large-scale production. The prepared phosphor sample was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermoluminescence (TL), photoluminescence (PL) and CIE techniques. For PL studies, the excitation and emission spectra of Gd2O3 phosphor doped with Er(3+) and Yb(3+) were recorded. The excitation spectrum was recorded at a wavelength of 551 nm and showed an intense peak at 276 nm. The emission spectrum was recorded at 276 nm excitation and showed peaks in all blue, green and red regions, which indicate that the prepared phosphor may act as a single host for white light-emitting diode (WLED) applications, as verified by International de I'Eclairage (CIE) techniques. From the XRD data, the calculated average crystallite size of Er(3+) and Yb(3+) -doped Gd2O3 phosphor is ~ 38 nm. A TL study was carried out for the phosphor using UV irradiation. The TL glow curve was recorded for UV, beta and gamma irradiations, and the kinetic parameters were also calculated. In addition, the trap parameters of the prepared phosphor were also studied using computerized glow curve deconvolution (CGCD). Copyright © 2015 John Wiley & Sons, Ltd.

Luminescence of Yb3+ ions in silica-based glasses synthesized by SPCVD

NASA Astrophysics Data System (ADS)

Savel'ev, E. A.; Krivovichev, A. V.; Yapaskurt, V. O.; Golant, K. M.

2017-02-01

The spectra and decay kinetics of Yb3+ single-ion and cooperative luminescence in silica-based optical slab waveguides are investigated. The slab waveguides with a high content of Yb and various amounts of P and Al additives to the light-guiding core glass were fabricated on the basis of fused and unfused glassy layers synthesized via surface-plasma chemical vapor deposition (SPCVD). Luminescence was pumped by laser diodes at ∼904 nm and ∼967 nm wavelengths and recorded in the 450-1175 nm spectral band. For the pure silica host doped with Yb, only the influence of cluster sizes on the luminescence decay kinetics is determined. It is found that the profusion of deposited glass with increased Al content favors separation by geometry of the Yb3+ and Tm3+ ions; the latter are present in the glass as an uncontrollable contamination. Evidence was found that at least two different types of Yb clusters were formed in P doped silica as a result of profusion.

InP tunnel junction for InGaAs/InP tandem solar cells

NASA Technical Reports Server (NTRS)

Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

1995-01-01

Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

Color-tunable up-conversion emission from Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+} tri-doped T-AgGd(W,Mo){sub 2}O{sub 8} phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jijian; Liu, Ni; Xu, Ling, E-mail: xuling@snnu.edu.cn

Graphical abstract: The doping ions tune the UC luminescence of the T- AgGd(W,Mo){sub 2}O{sub 8}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+} material. - Highlights: • AgGd(W,Mo){sub 2}O{sub 8}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+} phosphors show color-tunable blue, green, and red UC emissions. • The samples’ UC emission color can be switched with the concentrations of doped ions. • The blue, green and red UC mechanisms are interpreted reasonably as three- and two- photon process. - Abstract: Tetragonal Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+} tri-doped AgGd(W,Mo){sub 2}O{sub 8} phosphors were prepared by the high-temperature solid-state method. When the phosphors were excited at 980 nm, the UC emission ofmore » blue at 475 nm, green at 525 and 550 nm, and red at 656 nm were corresponding to the {sup 1}G{sub 4} → {sup 3}H{sub 6} transition of Tm{sup 3+} ions, the {sup 2}H{sub 11/2},{sup 4}S{sub 3/2} → {sup 4}I{sub 15/2} transitions of Er{sup 3+} ions, and the {sup 4}F{sub 9/2} → {sup 4}I{sub 15/2} transition of Er{sup 3+} ions, respectively. The blue UC emissions originate from a three-photon mechanism, while the green and red ones of Er{sup 3+} from two-photon process. The UC emission color of the Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+} tri-doped AgGdW{sub 2}O{sub 8} samples switched from green to white, and then to red depending on the concentrations of Er{sup 3+} and Tm{sup 3+}. After doping with Mo(VI), tetragonal AgGdW{sub 2}O{sub 8} was transformed into tetragonal AgGdMo{sub 2}O{sub 8}, resulting in a slightly enhanced UC luminescence intensity with the favor of the red emission of Er{sup 3+} ion.« less

Influence of Yb{sub 2}O{sub 3} on electrical and microstructural characteristics of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Kai; State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054; Luo, Yun

2015-09-15

Graphical abstract: Some Yb atoms entered in the lattice of CCTO substituted the Ca sites, the rest of Yb atoms concentrated at grain boundaries decreased the grain size. The dielectric constant was decreased by Yb doping. The dielectric loss of the CCTO could be greatly reduced at low frequency. - Highlights: • Yb atoms may take the place of Ca sites and concentrate at grain boundaries. • Tiny second phase corresponding to Yb may decrease the grain size. • Decrease of the grain size leads to the decrease of dielectric constant. • Yb doping could decrease the dielectric loss ofmore » CCTO. - Abstract: This paper focuses on the remarkable effects of Yb{sub 2}O{sub 3} doping on the microstructure and dielectric characteristics of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO). Samples were prepared by the solid phase reaction method and sintered in air at 1030 °C for 12 h. X-ray diffraction and X-ray photoelectron spectroscopy studies confirm that the primary phase is CCTO. Some Yb{sup 3+} ions may substitute into the Ca site at the center or zenith sites of the CCTO lattice hexahedron, while the rest of the Yb atoms may concentrate at grain boundaries. The grain size of Yb{sub 2}O{sub 3}-doped CCTO ceramics were examined by scanning electron microscopy and demonstrate sharp grain size reduction with Yb{sub 2}O{sub 3} doping. From dielectric property measurements, the Yb{sub 2}O{sub 3} doping reduces the dielectric constant of CCTO, and the dielectric loss is also reduced.« less

Comparative analysis of luminescent properties of germanate glass and double-clad optical fibers co-doped with Yb3+/Ho3+ ions

NASA Astrophysics Data System (ADS)

Pietrzycki, Marcin; Kochanowicz, Marcin; Romańczuk, Patryk; Żmojda, Jacek; Miluski, Piotr; Ragiń, Tomasz; Jeleń, Piotr; Sitarz, Maciej; Dorosz, Dominik

2016-09-01

The 2 μm and visible emission of low phonon (805 cm-1) germanate glasses and double - clad optical fiber co-doped with 0.7Yb2O3/(0.07-0.7)Ho2O3 ions have been investigated. Luminescence at 2 μm corresponding to Ho3+: 5I7 → 5I8 as well as upconversion luminescence in the visible spectral range corresponding to the Ho3+: 5S2(5F4)→5I8 (545 nm), and Ho3+: 5F5→5I8 (655 nm) transition, respectively were obtained. The optimization of the acceptor content and donor-acceptor ratio were conducted with the purpose of maximizing the luminescence intensity. The highest luminescence intensity in both spectral range was obtained in glass co-doped with 0.7Yb2O3/0.15 Ho2O3. Despite relatively small effective absorption coefficient of the optical fiber comparative analysis of luminescent properties of fabricated glasses (further core) and double - clad optical fiber showed significant contribution of reabsorption process of emitted ASE signal.

Research on up- and down-conversion emissions of Er3+/Yb3+ co-doped phosphate glass ceramic

NASA Astrophysics Data System (ADS)

Ming, Chengguo; Song, Feng; An, Liqun; Ren, Xiaobin; Yuan, Yize; Cao, Yang; Wang, Gangzhi

2012-12-01

By high-temperature melting method and thermal treatment technology, Er3+/Yb3+ co-doped phosphate glass and glass ceramic samples were prepared. The luminescence spectra of the glass and glass ceramic samples were studied under 975 nm excitation. In visible and near-infrared bands, the emission intensity of the glass ceramic is stronger than that of the glass. The glass ceramic can comprehensively improve the luminous characters of the precursor glass. The phosphate glass ceramic will be valuable luminescence materials.

Single n+-i-n+ InP nanowires for highly sensitive terahertz detection.

PubMed

Peng, Kun; Parkinson, Patrick; Gao, Qian; Boland, Jessica L; Li, Ziyuan; Wang, Fan; Mokkapati, Sudha; Fu, Lan; Johnston, Michael B; Tan, Hark Hoe; Jagadish, Chennupati

2017-03-24

Developing single-nanowire terahertz (THz) electronics and employing them as sub-wavelength components for highly-integrated THz time-domain spectroscopy (THz-TDS) applications is a promising approach to achieve future low-cost, highly integrable and high-resolution THz tools, which are desirable in many areas spanning from security, industry, environmental monitoring and medical diagnostics to fundamental science. In this work, we present the design and growth of n + -i-n + InP nanowires. The axial doping profile of the n + -i-n + InP nanowires has been calibrated and characterized using combined optical and electrical approaches to achieve nanowire devices with low contact resistances, on which the highly-sensitive InP single-nanowire photoconductive THz detectors have been demonstrated. While the n + -i-n + InP nanowire detector has a only pA-level response current, it has a 2.5 times improved signal-to-noise ratio compared with the undoped InP nanowire detector and is comparable to traditional bulk THz detectors. This performance indicates a promising path to nanowire-based THz electronics for future commercial applications.

Multicolor up conversion emission and color tunability in Yb 3+/Tm 3+/Ho 3+ triply doped heavy metal oxide glasses

NASA Astrophysics Data System (ADS)

Ledemi, Yannick; Manzani, Danilo; Ribeiro, Sidney J. L.; Messaddeq, Younes

2011-10-01

Multicolor and white light emissions have been achieved in Yb 3+, Tm 3+ and Ho 3+ triply doped heavy metal oxide glasses upon laser excitation at 980 nm. The red (660 nm), green (547 nm) and blue (478 nm) up conversion emissions of the rare earth (RE) ions triply doped TeO 2-GeO 2-Bi 2O 3-K 2O glass (TGBK) have been investigated as a function of the RE concentration and excitation power of the 980 nm laser diode. The most appropriate combination of RE in the TGBK glass host (1.6 wt% Yb 2O 3, 0.6 wt% Tm 2O 3 and 0.1 wt% Ho 2O 3) has been determined with the purpose to tune the primary colors (RGB) respective emissions and generate white light emission by varying the pump power. The involved infrared to visible up conversion mechanisms mainly consist in a three-photon blue up conversion of Tm 3+ ions and a two-photon green and red up conversions of Ho 3+ ions. The resulting multicolor emissions have been described according to the CIE-1931 standards.

A temperature sensor based on the enhanced upconversion luminescence of Li+ doped NaLuF4:Yb3+,Tm3+/Er3+ nano/microcrystals.

PubMed

Qiang, Qinping; Du, Shanshan; Ma, Xinlong; Chen, Wenbo; Zhang, Gangyi; Wang, Yuhua

2018-05-09

In this paper, fluorescent and optical temperature sensing bi-functional Li+-doping NaLuF4:Ln (Ln = Yb3+, Tm3+/Er3+) nanocrystals were synthesized via a simple hydrothermal method using oleic acid as a capping ligand. The crystal phase, size, upconversion (UC) properties, and optical temperature sensing characteristics of the crystals can be easily modified by Li+ doping. The results reveal that additional Li+ can promote the transformation from the hexagonal phase to the cubic phase and reduce the size of the nanocrystals. In addition, NaLuF4:Ln (Ln = Yb3+, Tm3+, Li+) nanocrystals present efficient near infrared (NIR) emission, which is beneficial for in vivo biomedical applications due to the increased penetration depth and low radiation damage of NIR light in bio-tissues. More importantly, under 980 nm excitation, the temperature dependent UCL from the 2H11/2 and 4S3/2 levels of Er3+ ions in NaLuF4:Yb3+,Er3+,Li+ microcrystals was investigated systematically. The fluorescence intensity ratios (FIR) of the pairs of thermally coupled levels were studied as a function of temperature in the range of 298-523 K. The maximum sensor sensitivities were found to be about 0.0039 K-1 (523 K) by exploiting the UC emissions from the 2H11/2 and 4S3/2 levels. This suggests that the Li+-doped upconversion luminescence (UCL) materials are promising prototypes for application as multi-mode probes for use in bio-separation and optical thermometers.

Yb-doped large mode area tapered fiber with depressed cladding and dopant confinement

NASA Astrophysics Data System (ADS)

Roy, V.; Paré, C.; Labranche, B.; Laperle, P.; Desbiens, L.; Boivin, M.; Taillon, Y.

2017-02-01

A polarization-maintaining Yb-doped large mode area fiber with depressed-index inner cladding layer and confinement of rare-earth dopants has been drawn as a long tapered fiber. The larger end features a core/clad diameter of 56/400 μm and core NA 0.07, thus leading to an effective mode area over 1000 μm2. The fiber was tested up to 100 W average power, with near diffraction-limited output as the beam quality M2 was measured < 1.2. As effective single-mode guidance is enforced in the first section due to enhanced bending loss, subsequent adiabatic transition of the mode field in the taper section preserves single-mode amplification towards the larger end of the fiber.

X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF2:Yb but Not in SrF2:Yb.

PubMed

Hughes-Currie, Rosa B; Ivanovskikh, Konstantin V; Wells, Jon-Paul R; Reid, Michael F; Gordon, Robert A; Seijo, Luis; Barandiarán, Zoila

2017-03-16

Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d-f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators. We report high-resolution X-ray-excited optical (IR to UV) luminescence spectra of CaF 2 :Yb and SrF 2 :Yb samples excited at 8949 eV and 80 K. Ionizing radiation excites the known anomalous emission of ytterbium in the CaF 2 host but not in the SrF 2 host. Wave function-based ab initio calculations of host-to-dopant electron transfer and Yb 2+ /Yb 3+ intervalence charge transfer explain the difference. The model also explains the lack of anomalous emission in Yb-doped SrF 2 excited by VUV radiation.

Universal heat conduction in Ce 1-xYb xCoIn 5: Evidence for robust nodal d-wave superconducting gap

DOE PAGES

Xu, Y.; Petrovic, C.; Dong, J. K.; ...

2016-02-01

In the heavy-fermion superconductor Ce 1-xYb xCoIn 5, Yb doping was reported to cause a possible change from nodal d-wave superconductivity to a fully gapped d-wave molecular superfluid of composite pairs near x ≈ 0.07 (nominal value x nom = 0.2). Here we present systematic thermal conductivity measurements on Ce 1-xYb xCoIn 5 (x = 0.013, 0.084, and 0.163) single crystals. The observed finite residual linear term κ 0/T is insensitive to Yb doping, verifying the universal heat conduction of the nodal d-wave superconducting gap in Ce 1-xYb xCoIn 5. Similar universal heat conduction is also observed in the CeCo(Inmore » 1–yCd y) 5 system. Furthermore, these results reveal a robust nodal d-wave gap in CeCoIn 5 upon Yb or Cd doping.« less

Role of ytterbium-erbium co-doped gadolinium molybdate (Gd₂(MoO₄)₃:Yb/Er) nanophosphors in solar cells.

PubMed

Jin, Xiao; Li, Haiyang; Li, Dongyu; Zhang, Qin; Li, Feng; Sun, Weifu; Chen, Zihan; Li, Qinghua

2016-09-05

Insufficient harvest of solar light energy is one of the obstacles for current photovoltaic devices to achieve high performance. Especially, conventional organic/inorganic hybrid solar cells (HSCs) based on PTB7 as p-type semiconductor can only utilize 400-800 nm solar spectrum. One effective strategy to overcome this obstacle is the introduction of up-conversion nanophosphors (NPs), in the virtue of utilizing the near infrared region (NIR) of solar radiation. Up-conversion can convert low-energy photons to high-energy ones through multi-photon processes, by which the solar spectrum is tailored to well match the absorptive domain of the absorber. Herein we incorporate erbium-ytterbium co-doped gadolinium molybdate (Gd₂(MoO₄)₃, GMO), denoted as GMO:Yb/Er, into TiO₂ acceptor film in HSCs to enhance the light harvest. Here Er³⁺ acts as activator while Yb-MoO₄ ^2- is the joint sensitizer. Facts proved that the GMO:Yb/Er single crystal NPs are capable of turning NIR photons to visible photons that can be easily captured by PTB7. Studies on time-resolved photoluminescence demonstrate that electron transfer rate at the interface increases sharply from 0.65 to 1.42 × 10⁹ s^-1. As a result, the photoelectric conversion efficiency of the GMO:Yb/Er doped TiO₂/PTB7 HSCs reach 3.67%, which is increased by around 25% compared to their neat PTB7/TiO₂ counterparts (2.94%). This work may open a hopeful way to take the advantage of those conversional rare-earth ion doped oxides that function in tailoring solar light spectrum for optoelectronic applications.

Ultra-large core birefringent Yb-doped tapered double clad fiber for high power amplifiers.

PubMed

Fedotov, Andrey; Noronen, Teppo; Gumenyuk, Regina; Ustimchik, Vasiliy; Chamorovskii, Yuri; Golant, Konstantin; Odnoblyudov, Maxim; Rissanen, Joona; Niemi, Tapio; Filippov, Valery

2018-03-19

We present a birefringent Yb-doped tapered double-clad fiber with a record core diameter of 96 µm. An impressive gain of over 38 dB was demonstrated for linearly polarized CW and pulsed sources at a wavelength of 1040 nm. For the CW regime the output power was70 W. For a mode-locked fiber laser a pulse energy of 28 µJ with 292 kW peak power was reached at an average output power of 28 W for a 1 MHz repetition rate. The tapered double-clad fiber has a high value of polarization extinction ratio at 30 dB and is capable of delivering the linearly polarized diffraction-limited beam (M 2 = 1.09).

Strong emission in Yb3+/Er3+ co-doped phosphate glass ceramics

NASA Astrophysics Data System (ADS)

Liu, Yanling; Song, Feng; Jia, Guozhi; Zhang, Yanbang; Tang, Yi

Yb3+/Er3+ co-doped phosphate glass and glass ceramics were prepared by high-temperature melting method. The X-ray diffraction, transmission electron micrographs, up-conversion and infrared emissions, photothermal conversion properties of the samples have been measured. The results showed the annealing time had a great impact on the microstructure and luminous performance of the phosphate glass. At the beginning of annealing, the metaphosphate crystals were firstly dissolved out. The metaphosphate crystals gradually turned into the orthophosphate with the increasing of annealing time. The emission intensity of the sample was obviously improved after the precursor glass was annealed. The up-conversion and infrared emissions of the sample annealed at 600 °C for 24 h, reached the maximum intensity. Compared with the photothermal properties of glass, the lower photothermal conversion efficiency of the glass ceramics testified the strong emission.

A novel optical fibre doped with the nano-material as InP

NASA Astrophysics Data System (ADS)

Chen, Xi; Lee, Ly Guat; Zhang, Ru

2007-11-01

As the key of these optical devices which are widely used in the communication system, high nonlinear optical fibre will play an important role in the future optical fibre communication. With recent growth of nano-technology, researchers are hoping to obtain some kinds of optical fibre by combining the optical fibre with the nanotechnology. According to this current situation, the optical fibre doped with nano-material as InP (indium phosphide) is manufactured by using the MCVD (modified chemical vapor deposition) technology after our comprehensive consideration of many relative factors. Proved by experiments, this novel optical fibre has an excellent waveguide characteristic. After a consideration of the model of this novel optical fibre, its propagation constant β has been simulated by using the FEM (finite element method), and the graphs of presentation of magnetic field of the core are also obtained. In accordance with the results, the effective refractive index n eff = 1.401 has be calculated. Both the calculated result and the simulated graphs are matching well with the test, and this result is a step-stone bridge for future research of nonlinear parameter on this novel optical fiber.

Evaluation of TeO2 content on the optical and spectroscopic properties of Yb3+-doped calcium borotellurite glasses.

PubMed

Lima, A M O; Gomes, J F; Hegeto, F L; Medina, A N; Steimacher, A; Barboza, M J

2018-03-15

This paper reports the synthesis and the characterization of Yb 3+ -doped calcium borotellurite (CaBTeX) glasses with composition 10CaF 2 -(29.5-0.4x)CaO-(60-0.6x)B 2 O 3 -xTeO 2 -0.5Yb 2 O 3 (x=10, 16, 22, 31 and 54mol%). The results of XRD confirm the amorphous character of all the samples. The density, molar volume, refractive index and electronic polarizability values show an increase with TeO 2 content. Otherwise, the optical band gap energy shows a decrease with the increase of TeO 2 content. The replacement of CaO and B 2 O 3 by TeO 2 changes the glass structure, which decreases the excited Yb 3+ /cm 3 and, consequently, the luminescence intensity. The temperature dependence of luminescence was studied for all the samples up to 420K. The fluorescence lifetime does not change significantly due to TeO 2 addition. In addition, absorption and emission cross section were calculated and present high values as compared to other tellurite and phosphate glasses. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of TeO2 content on the optical and spectroscopic properties of Yb3 +-doped calcium borotellurite glasses

NASA Astrophysics Data System (ADS)

Lima, A. M. O.; Gomes, J. F.; Hegeto, F. L.; Medina, A. N.; Steimacher, A.; Barboza, M. J.

2018-03-01

This paper reports the synthesis and the characterization of Yb3 +-doped calcium borotellurite (CaBTeX) glasses with composition 10CaF2-(29.5 - 0.4x)CaO-(60 - 0.6x)B2O3-xTeO2-0.5Yb2O3 (x = 10, 16, 22, 31 and 54 mol%). The results of XRD confirm the amorphous character of all the samples. The density, molar volume, refractive index and electronic polarizability values show an increase with TeO2 content. Otherwise, the optical band gap energy shows a decrease with the increase of TeO2 content. The replacement of CaO and B2O3 by TeO2 changes the glass structure, which decreases the excited Yb3 +/cm3 and, consequently, the luminescence intensity. The temperature dependence of luminescence was studied for all the samples up to 420 K. The fluorescence lifetime does not change significantly due to TeO2 addition. In addition, absorption and emission cross section were calculated and present high values as compared to other tellurite and phosphate glasses.

The upconversion luminescence and magnetism in Yb3+/Ho3+ co-doped LaF3 nanocrystals for potential bimodal imaging

NASA Astrophysics Data System (ADS)

Syamchand, Sasidharanpillai S.; George, Sony

2016-12-01

Biocompatible upconversion nanoparticles with multifunctional properties can serve as potential nanoprobes for multimodal imaging. Herein, we report an upconversion nanocrystal based on lanthanum fluoride which is developed to address the imaging modalities, upconversion luminescence imaging and magnetic resonance imaging (MRI). Lanthanide ions (Yb3+ and Ho3+) doped LaF3 nanocrystals (LaF3 Yb3+/Ho3+) are fabricated through a rapid microwave-assisted synthesis. The hexagonal phase LaF3 nanocrystals exhibit nearly spherical morphology with average diameter of 9.8 nm. The inductively coupled plasma mass spectrometry (ICP-MS) analysis estimated the doping concentration of Yb3+ and Ho3+ as 3.99 and 0.41%, respectively. The nanocrystals show upconversion luminescence when irradiated with near-infrared (NIR) photons of wavelength 980 nm. The emission spectrum consists of bands centred at 542, 645 and 658 nm. The stronger green emission at 542 nm and the weak red emissions at 645 and 658 nm are assigned to 5S2 → 5I8 and 5F5 → 5I8 transitions of Ho3+, respectively. The pump power dependence of luminescence intensity confirmed the two-photon upconversion process. The nanocrystals exhibit paramagnetism due to the presence of lanthanide ion dopant Ho3+ and the magnetization is 19.81 emu/g at room temperature. The nanocrystals exhibit a longitudinal relaxivity ( r 1) of 0.12 s-1 mM-1 and transverse relaxivity ( r 2) of 28.18 s-1 mM-1, which makes the system suitable for developing T2 MRI contrast agents based on holmium. The LaF3 Yb3+/Ho3+ nanocrystals are surface modified by PEGylation to improve biocompatibility and enhance further functionalisation. The PEGylated nanocrystals are found to be non-toxic up to 50 μg/mL for 48 h of incubation, which is confirmed by the MTT assay as well as morphological studies in HeLa cells. The upconversion luminescence and magnetism together with biocompatibility enables the adaptability of the present system as a nanoprobe for potential

Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core-shell nanoparticles for biomedical imaging

NASA Astrophysics Data System (ADS)

Kamińska, Izabela; Elbaum, Danek; Sikora, Bożena; Kowalik, Przemysław; Mikulski, Jakub; Felcyn, Zofia; Samol, Piotr; Wojciechowski, Tomasz; Minikayev, Roman; Paszkowicz, Wojciech; Zaleszczyk, Wojciech; Szewczyk, Maciej; Konopka, Anna; Gruzeł, Grzegorz; Pawlyta, Mirosława; Donten, Mikołaj; Ciszak, Kamil; Zajdel, Karolina; Frontczak-Baniewicz, Małgorzata; Stępień, Piotr; Łapiński, Mariusz; Wilczyński, Grzegorz; Fronc, Krzysztof

2018-01-01

Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core-shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core-shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+-{{{{MoO}}}4}2- (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core-shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.

Efficient Nd3+→Yb3+ energy transfer processes in high phonon energy phosphate glasses for 1.0 μm Yb3+ laser

NASA Astrophysics Data System (ADS)

Rivera-López, F.; Babu, P.; Basavapoornima, Ch.; Jayasankar, C. K.; Lavín, V.

2011-06-01

Efficient Nd3+→Yb3+ resonant and phonon-assisted energy transfer processes have been observed in phosphate glasses and have been studied using steady-state and time-resolved optical spectroscopies. Results indicate that the energy transfer occurs via nonradiative electric dipole-dipole processes and is enhanced with the concentration of Yb3+ acceptor ions, having an efficiency higher than 75% for the glass doped with 1 mol% of Nd2O3 and 4 mol% of Yb2O3. The luminescence decay curves show a nonexponential character and the energy transfer microscopic parameter calculated with the Inokuti-Hirayama model gives a value of 240 × 10-40 cm6 s-1, being one of the highest reported in the literature for Nd3+-Yb3+ co-doped matrices. From the steady-state experimental absorption and emission cross-sections, a general expression for estimating the microscopic energy transfer parameter is proposed based upon the theoretical methods developed by Miyakawa and Dexter and Tarelho et al. This expression takes into account all the resonant mechanisms involved in an energy transfer processes together with other phonon-assisted nonvanishing overlaps. The value of the Nd3+→Yb3+ energy transfer microscopic parameter has been calculated to be 200 × 10-40 cm6 s-1, which is in good agreement with that obtained from the Inokuti-Hirayama fitting. These results show the importance of the nonresonant phonon-assisted Nd3+→Yb3+ energy transfer processes and the great potential of these glasses as active matrices in the development of multiple-pump-channel Yb3+ lasers.

Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics tuneable up-conversion phosphor

NASA Astrophysics Data System (ADS)

Méndez-Ramos, J.; Rodriguez, V. D.; Tikhomirov, V. K.; Del-Castillo, J.; Yanes, A. C.

2008-08-01

Transparent Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics have been prepared, 32(SiO{2}) 9(AlO{1.5}) 31.5(CdF{2}) 18.5(PbF{2}) 5.5(ZnF{2}): 3.5(Yb-Er-TmF{3}) mol%, where the co-dopants partition mostly to the fluoride PbF{2}-based nano-crystals. A comparative study of the up-conversion luminescence in nano-glass-ceramics and its precursor glass indicates that these materials can be used as blue/green/red tuneable up-conversion phosphor, in particular for white light generation. A ratio between blue, green and red emission bands of the Tm3+ and Er3+ can be widely varied with nano-ceramming of the precursor glass and with changing a pump power of luminescence. The change in the ratio between the blue, green and red emission bands is explained to be due to substantial lowering phonon energy and shortening of inter-dopant distances with nano-ceramming of the precursor glass and due to change in the ratio of 2- and 3-photon up-conversion processes with pump power.

ZnMoO4:Er3+,Yb3+ phosphor with controlled morphology and enhanced upconversion through alkali ions doping

NASA Astrophysics Data System (ADS)

Luitel, Hom Nath; Chand, Rumi; Watari, Takanori

2018-04-01

A facile hydrothermal method was used to synthesize ZnMoO4:Er3+,Yb3+ nanoparticles. The shapes and sizes of the nanoparticles were well tuned by simply monitoring the pH of the starting solution. Microballs consisting of agglomerated nanograins were observed at strong acidic condition. At mild pH, plates and rectangular particles were realized, while strong basic pH stabilized rods. Further increasing pH to extremely basic conditions (pH > 13), rods changed to fragile hairy structures. The nucleation and growth mechanism of nanograins to form different morphology nanoparticles were studied and illustrated. XRD patterns confirmed well crystalline, triclinic structure despite small amount of aliovalent metal ions doping. Under 980 nm excitation, the ZnMoO4:Er3+,Yb3+ nanophosphor exhibited strong green (centered at 530 and 560 nm) and weak red (centered at 660 nm) upconversion (UC) emissions. Substitution of part of the Zn2+ ions by monovalent alkali ions intensified the UC emission intensities drastically. The order of intensification was K+>Na+>Li+>Rb+>no alkali ion. When Zn2+ ions were substituted with 10 at% K+ ions, the green and red UC emissions intensities increased by more than 50 and 15 folds, respectively. Time dependent measurements confirmed efficient Yb to Er energy transfer in the ZnMoO4:Er3+,Yb3+,K+ nanophosphor. The optimized ZnMoO4:Er3+,Yb3+,K+ phosphor exhibited intense UC emissions with 0.31% quantum yield. The upconverted light is visible to naked eye while pumping by laser of less than 1 mW power and opens door for variety of novel applications.

Hydrogen passivation of N(+)-P and P(+)-N heteroepitaxial InP solar cell structures

NASA Technical Reports Server (NTRS)

Chatterjee, Basab; Davis, William C.; Ringel, Steve A.; Hoffman, Richard, Jr.

1996-01-01

Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n-p and p-n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)-p and p(+)-n heteroepitaxial InP cell structures from as-grown values of 5-7 x 10(exp 14) cm(exp -3), down to 3-5 x 10(exp 12) cm(exp -3). All dopants were successfully reactivated by a 400 C, 5 minute anneal with no detectable activation of deep levels. One to five analysis indicated a subsequent approximately 100 fold decrease in reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)-n structures. In addition to being passivated, dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

Hydrogen Passivation of N(+)P and P(+)N Heteroepitaxial InP Solar Cell Structures

NASA Technical Reports Server (NTRS)

Chatterjee, B.; Davis, W. C.; Ringel, S. A.; Hoffman, R., Jr.

1995-01-01

Dislocations and related point defect complexes caused by lattice mismatch currently limit the performance of heteroepitaxial InP cells by introducing shunting paths across the active junction and by the formation of deep traps within the base region. We have previously demonstrated that plasma hydrogenation is an effective and stable means to passivate the electrical activity of such defects in specially designed heteroepitaxial InP test structures to probe hydrogen passivation at typical base depths within a cell structure. In this work, we present our results on the hydrogen passivation of actual heteroepitaxial n(+)p and p(+)n InP cell structures grown on GaAs substrates by metalorganic chemical vapor deposition (MOCVD). We have found that a 2 hour exposure to a 13.56 MHz hydrogen plasma at 275 C reduces the deep level concentration in the base regions of both n(+)p and p(+)n heteroepitaxial InP cell structures from as-grown values of 5 - 7 x 10(exp 14)/cc, down to 3 - 5 x 10(exp 12)/cc. All dopants were successfully reactivated by a 400 C, 5 minute anneal With no detectable activation of deep levels. I-V analysis indicated a subsequent approx. 100 fold decrease In reverse leakage current at -1 volt reverse bias, and an improved built in voltage for the p(+)n structures. ln addition to being passivated,dislocations are also shown to participate in secondary interactions during hydrogenation. We find that the presence of dislocations enhances hydrogen diffusion into the cell structure, and lowers the apparent dissociation energy of Zn-H complexes from 1.19 eV for homoepitaxial Zn-doped InP to 1.12 eV for heteroepitaxial Zn-doped InP. This is explained by additional hydrogen trapping at dislocations subsequent to the reactivation of Zn dopants after hydrogenation.

NIR luminescence studies on Er{sup 3+}:Yb{sup 3+} co-doped sodium telluroborate glasses for lasers and optical amplifer applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annapoorani, K.; Marimuthu, K., E-mail: mari-ram2000@yahoo.com; Murthy, N. Suriya

2016-05-23

Er{sup 3+}:Yb{sup 3+} co-doped Sodium telluroborate glasses were prepared with the chemical composition (49.5–x)B{sub 2}O{sub 3}+25TeO{sub 2}+5Li{sub 2}CO{sub 3}+10ZnO+10NaF+0.5Er{sub 2}O{sub 3}+xYb{sub 2}O{sub 3} (where x= 0.1, 0.5, 1.0 and 2.0 in mol %) following the melt quenching technique. With the addition of Yb{sup 3+} ions into Er{sup 3+} ions in the prepared glasses, the absorption cross-section values were found to increase due to the effective energy transfer from {sup 2}F{sub 5/2} level of Yb{sup 3+} ions to the {sup 4}I{sub 11/2} level of Er{sup 3+} ions. The fluorescence around 1550 nm correspond to the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition wasmore » observed under 980 nm pumping. Among the present glasses, integrated intensity was found to be higher for 1.0 mol% Yb{sup 3+} ion glass. The parameters such as stimulated emission cross- section, Gain bandwidth and quantum efficiency of the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition was found to be higher for the NTBE1.0Y glass and the same is suggested for potential NIR lasers and optical amplifier applications.« less

Growth, spectroscopy and lasing of the Yb-doped monoclinic Gd2SiO5 in the prospect of hydrogen laser cooling with Lyman-α radiation

NASA Astrophysics Data System (ADS)

Cabaret, L.; Robert, J.; Lebbou, K.; Brenier, A.; Cabane, H.

2016-12-01

We have grown good optical quality 10% Yb-doped Gd2SiO5 monocrystal by the Czochralski technique. The Yb segregation coefficient was measured to be 0.747. In agreement with the monoclinic symmetry of the host, the Yb fluorescence extrema were found to deviate from the Nm and Ng principal axes and a fourth spectroscopic parameter representing the rotation of the fluorescence distribution was introduced for a full description. Diode pumped laser operation at Brewster incidence was demonstrated to be significantly more efficient if the lasing propagation corresponds to the maximum fluorescence inside the crystal. We obtained a laser emission tunable between 1079 and 1100 nm, showing that our crystal is the best choice for the application to the production of QCW Lyman-α radiation by resonant four-wave-mixing in mercury vapor.

Fabrication and characterization of a phosphosilicate YDF with high Yb absorbance and low background loss

NASA Astrophysics Data System (ADS)

Kim, Seong-Jin; Hujimaki, Yosuke; Taniguchi, Hirokazu; Kinoshita, Hiroaki; Sato, Kenji

2014-03-01

In this paper, we report fabrication and investigation of ytterbium-doped phosphorsilicate fiber (P co-doped YDF) with high Yb content, low numerical aperture, and low background loss. The P co-doped YDF is fabricated by MCVD using the vapor sources of Yb, SiCl4, AlCl3, and POCl3, and by the gas-phase doping method. The optical properties of this P co-doped YDF are compared with Al co-doped and Al:P co-doped YDFs with low background losses. The minimum background loss of the P co-doped YDF in the spectral range from 1100 to 1380 nm is as low as ~3 dB/km. This is nearly independent of the Yb and P contents because soot deposition and collapsing conditions are properly optimized (i.e., the P co-doped YDF from a non-optimized process shows a few hundred dB/km). The excess loss induced by PD, for the P co-doped YDF, was dramatically reduced compared to both Al co-doped and Al:P co-doped YDFs. The optical slope efficiency of the P co-doped YDF is about 80%, depending on the pumping wavelength and fiber length. The fiber colors during pumping are blue for both the P co-doped and Al:P co-doped YDFs. Based on the results from a prolonged test, the output power of the P co-doped YDF is highly stable, with an initial degradation of 2-3%; which demonstrate improvement in PD resistivity with P incorporation into the glass, compared to the Al:P co-doped YDF with degradation above 6%.

Microstructural and electrical characteristics of rare earth oxides doped ZnO varistor films

NASA Astrophysics Data System (ADS)

Jiao, Lei; Mei, Yunzhu; Xu, Dong; Zhong, Sujuan; Ma, Jia; Zhang, Lei; Bao, Li

2018-02-01

ZnO-Bi2O3 varistor films doped with two kinds of rare earth element oxides (Lu2O3 and Yb2O3) were prepared by the sol-gel method. The effects of Lu2O3/Yb2O3 doping on the microstructure and electrical characteristics of ZnO-Bi2O3 varistor films were investigated. All samples show a homogenized morphology and an improved nonlinear relationship between the electric field (E) and current density (I). Both Yb2O3 and Lu2O3 doping can decrease the grain size of ZnO-Bi2O3 varistor films and improve the electrical properties, which have a positive effect on the development of ZnO varistor ceramics. Yb2O3 doping significantly increases the dielectric constant at low frequency. 0.2 mol. % Yb2O3 doped ZnO-Bi2O3 varistor films exhibit the highest nonlinear coefficient (2.5) and the lowest leakage current (328 μA) among Lu2O3/Yb2O3 doped ZnO-Bi2O3 varistor films. Similarly, 0.1 mol. % Lu2O3 doping increases the nonlinear coefficient to 1.9 and decrease the leakage current to 462 μA.

Crystal structure of YbCu6In6 and mixed valence behavior of Yb in YbCu(6-x)In(6+x) (x = 0, 1, and 2) solid solution.

PubMed

Subbarao, Udumula; Peter, Sebastian C

2012-06-04

High quality single crystals of YbCu(6)In(6) have been grown using the flux method and characterized by means of single crystal X-ray diffraction data. YbCu(6)In(6) crystallizes in the CeMn(4)Al(8) structure type, tetragonal space group I4/mmm, and the lattice constants are a = b = 9.2200(13) Å and c = 5.3976(11) Å. The crystal structure of YbCu(6)In(6) is composed of pseudo-Frank-Kasper cages filled with one ytterbium atom in each ring. The neighboring cages share corners along [100] and [010] to build the three-dimensional network. YbCu(6-x)In(6+x) (x = 0, 1, and 2) solid solution compounds were obtained from high frequency induction heating and characterized using powder X-ray diffraction. The magnetic susceptibilities of YbCu(6-x)In(6+x) (x = 0, 1, and 2) were investigated in the temperature range 2-300 K and showed Curie-Weiss law behavior above 50 K, and the experimentally measured magnetic moment indicates mixed valent ytterbium. A deviation in inverse susceptibility data at 200 K suggests a valence transition from Yb(2+) to Yb(3+) as the temperature decreases. An increase in doping of Cu at the Al2 position enhances the disorder in the system and enhancement in the trivalent nature of Yb. Electrical conductivity measurements show that all compounds are of a metallic nature.

The Upconversion Luminescence of Er3+/Yb3+/Nd3+ Triply-Doped β-NaYF4 Nanocrystals under 808-nm Excitation

PubMed Central

Tian, Lijiao; Xu, Zheng; Zhao, Suling; Cui, Yue; Liang, Zhiqin; Zhang, Junjie; Xu, Xurong

2014-01-01

In this paper, Nd3+–Yb3+–Er3+-doped β-NaYF4 nanocrystals with different Nd3+ concentrations are synthesized, and the luminescence properties of the upconversion nanoparticles (UCNPs) have been studied under 808-nm excitation for sensitive biological applications. The upconversion luminescence spectra of NaYF4 nanoparticles with different dopants under 808-nm excitation proves that the Nd3+ ion can absorb the photons effectively, and the Yb3+ ion can play the role of an energy-transfer bridging ion between the Nd3+ ion and Er3+ ion. To investigate the effect of the Nd3+ ion, the decay curves of the 4S3/2 → 4I15/2 transition at 540 nm are measured and analyzed. The NaYF4: 20% Yb3+, 2% Er3+, 0.5% Nd3+ nanocrystals have the highest emission intensity among all samples under 808-nm excitation. The UC (upconversion) mechanism under 808-nm excitation is discussed in terms of the experimental results. PMID:28788246

Gold nanorod as saturable absorber for Q-switched Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Xu-De; Luo, Zhi-Chao; Liu, Hao; Zhao, Nian; Liu, Meng; Zhu, Yan-Fang; Xue, Jian-Ping; Luo, Ai-Ping; Xu, Wen-Cheng

2015-07-01

We reported on the generation of Q-switched pulse in an Yb-doped fiber laser by using a filmy polyvinyl alcohol (PVA)-based gold nanorods (GNRs) saturable absorber (SA). The GNRs are synthesized through seed-mediated method whose longitudinal surface plasmon resonance (SPR) absorption peak is located at 1038 nm. The modulation depth of the GNRs SA is ∼4.06%. By gradually increasing the pump power from 62 mW to 128 mW, the repetition rate of Q-switched pulse increases from 8.78 kHz to 20.78 kHz and the pulse duration decreases from 9.43 μs to 3.65 μs. In addition, the dual-wavelength switchable Q-switched operation was also observed. The obtained results further expand the applications of GNRs SA to the field of Q-switched pulsed fiber lasers at 1.0 μm waveband.

Carbon incorporation in InP grown by metalorganic chemical vapor deposition and application to InP/InGaAs heterojunction bipolar transistors

NASA Astrophysics Data System (ADS)

Stockman, S. A.; Fresina, M. T.; Hartmann, Q. J.; Hanson, A. W.; Gardner, N. F.; Baker, J. E.; Stillman, G. E.

1994-04-01

The incorporation of residual carbon has been studied for InP grown at low temperatures using TMIn and PH3 by low-pressure metalorganic chemical vapor deposition. n-type conduction is observed with electron concentrations as high as 1×1018 cm-3, and the electrical activation efficiency is 5%-15%. Carbon incorporation is found to be highly dependent on substrate temperature, suggesting that the rate-limiting step is desorption of CHy (0≤y≤3) from the surface during growth. Hydrogen is also incorporated in the layers during growth. The electron mobilities are lower for C-doped InP than for Si-doped InP. InP/InGaAs heterojunction bipolar transistors with C as the p-type base dopant and either Si or C as the n-type emitter dopant have been fabricated and compared. Devices with a carbon-doped base and emitter showed degraded performance, likely as a result of deep levels incorporated during growth of the emitter.

High-Yield Growth and Characterization of ⟨100⟩ InP p-n Diode Nanowires.

PubMed

Cavalli, Alessandro; Wang, Jia; Esmaeil Zadeh, Iman; Reimer, Michael E; Verheijen, Marcel A; Soini, Martin; Plissard, Sebastien R; Zwiller, Val; Haverkort, Jos E M; Bakkers, Erik P A M

2016-05-11

Semiconductor nanowires are nanoscale structures holding promise in many fields such as optoelectronics, quantum computing, and thermoelectrics. Nanowires are usually grown vertically on (111)-oriented substrates, while (100) is the standard in semiconductor technology. The ability to grow and to control impurity doping of ⟨100⟩ nanowires is crucial for integration. Here, we discuss doping of single-crystalline ⟨100⟩ nanowires, and the structural and optoelectronic properties of p-n junctions based on ⟨100⟩ InP nanowires. We describe a novel approach to achieve low resistance electrical contacts to nanowires via a gradual interface based on p-doped InAsP. As a first demonstration in optoelectronic devices, we realize a single nanowire light emitting diode in a ⟨100⟩-oriented InP nanowire p-n junction. To obtain high vertical yield, which is necessary for future applications, we investigate the effect of the introduction of dopants on the nanowire growth.

[Up-conversion luminescent materials of Y2O3: RE(RE=Er or Er/Yb) prepared by sol-gel combustion synthesis].

PubMed

Han, Peng-de; Zhang, Le; Huang, Xiao-gu; Wang, Li-xi; Zhang, Qi-tu

2010-11-01

Y2O3 powders doped with rare-earth ions were synthesized by sol-gel combustion synthesis. Effects of different calcinating temperatures, Er+ doping concentration and Yb3+ doping concentration were investigated. It was shown that the single well crystallized Y2O3 powders could be obtained at 800 degrees C; as the calcinating temperature increased, the crystallinity and upconversion luminescence intensity were higher; the particle size was uniform around 1 microm at 900 degrees C; when Er3+ doping concentration was 1 mol%, the green upconversion luminescence intensity reached the maximum, but for red upconversion luminescence, when Er3+ doping concentration was 4 mol%, its luminescence intensity reached the maximum; as the ratio of Yb3+ to Er3+ was 4:1, the green emission intensity reached the maximum, while the red emission intensity was always increasing as Yb3+ doping concentration increased.

Direct visualization of gastrointestinal tract with lanthanide-doped BaYbF5 upconversion nanoprobes.

PubMed

Liu, Zhen; Ju, Enguo; Liu, Jianhua; Du, Yingda; Li, Zhengqiang; Yuan, Qinghai; Ren, Jinsong; Qu, Xiaogang

2013-10-01

Nanoparticulate contrast agents have attracted a great deal of attention along with the rapid development of modern medicine. Here, a binary contrast agent based on PAA modified BaYbF5:Tm nanoparticles for direct visualization of gastrointestinal (GI) tract has been designed and developed via a one-pot solvothermal route. By taking advantages of excellent colloidal stability, low cytotoxicity, and neglectable hemolysis of these well-designed nanoparticles, their feasibility as a multi-modal contrast agent for GI tract was intensively investigated. Significant enhancement of contrast efficacy relative to clinical barium meal and iodine-based contrast agent was evaluated via X-ray imaging and CT imaging in vivo. By doping Tm(3+) ions into these nanoprobes, in vivo NIR-NIR imaging was then demonstrated. Unlike some invasive imaging modalities, non-invasive imaging strategy including X-ray imaging, CT imaging, and UCL imaging for GI tract could extremely reduce the painlessness to patients, effectively facilitate imaging procedure, as well as rationality economize diagnostic time. Critical to clinical applications, long-term toxicity of our contrast agent was additionally investigated in detail, indicating their overall safety. Based on our results, PAA-BaYbF5:Tm nanoparticles were the excellent multi-modal contrast agent to integrate X-ray imaging, CT imaging, and UCL imaging for direct visualization of GI tract with low systemic toxicity. Copyright © 2013 Elsevier Ltd. All rights reserved.

Frequency upconversion and fluorescence intensity ratio method in Yb3+-ion-sensitized Gd2O3:Er3+-Eu3+ phosphors for display and temperature sensing

NASA Astrophysics Data System (ADS)

Ranjan, Sushil Kumar; Soni, Abhishek Kumar; Rai, Vineet Kumar

2017-09-01

Near infrared (NIR) to visible frequency upconversion emission studies in Er3+-Eu3+/Er3+-Eu3+-Yb3+ co-doped/tri-doped Gd2O3 phosphors prepared by the co-precipitation technique have been explored under 980 nm laser diode radiation. The developed phosphors were characterized with the help of XRD, FE-SEM and FTIR analysis. No upconversion (UC) emission was found in the Eu3+-doped Gd2O3 phosphor. UC emission from Eu3+ ions along with Er3+ ions was observed in Er3+-Eu3+ and Er3+-Eu3+-Yb3+ co-doped/tri-doped phosphors. The UC emission arising from the Er3+ and Eu3+ ions was enhanced several times due to the incorporation of Yb3+ ions. The processes involved in the UC emission were obtained on the basis of the effect of energy transfer/sensitization through the Yb3+ → Er3+ → Eu3+ process. The red/green intensity ratio was improved from 0.16 to 1.50 and 1.01 to 1.50 for Er3+-Eu3+-Yb3+ tri-doped phosphors as compared to the Er3+-doped and Er3+-Yb3+ co-doped phosphors, respectively, at a fixed pump power density. A UC fluorescence intensity ratio (FIR)-based temperature sensing study was performed in the prepared Er3+-Eu3+-Yb3+ tri-doped Gd2O3 phosphors for green upconversion emission bands in the 300 K-443 K temperature range. A maximum sensor sensitivity of about ˜0.0043 K-1 at 300 K was achieved for the synthesized tri-doped phosphors upon excitation with a 980 nm laser diode. The colour coordinates lying in the green-yellow region are invariant, with variation in pump power density and temperature. The observed results support the utility of the prepared tri-doped phosphors in optical temperature sensing, display devices and NIR to visible upconverters.

30-W Yb3+-pulsed fiber laser with wavelength tuning

NASA Astrophysics Data System (ADS)

Davydov, B. L.; Krylov, A. A.

2007-12-01

We have investigated various pulsed operation regimes of a diode-pumped Yb3+-doped fiber laser with both an acoustooptic filter and a shutter inside the resonator. To imbed the polarization-sensitive acoustooptic-tunable spectral filter into the polarization-nonmaintaining resonator, based on an “isotropic” single-mode fiber without “polarization’ losses, we have used a CaCO3 single-crystal nondispersive thermostable polarization splitter. Stable smooth bell-shaped laser pulses were obtained in the Q-switch generation regime across the entire wavelength tuning band. Their duration depended on the resonator travel time and their repetition rate was determined exclusively by the outer high-frequency generator controlling the acoustooptic shutter. A pulsed laser radiation tuning bandwidth of more than 20-nm at a repetition rate band of 10-100 kHz was observed in the amplification band of the Yb3+-doped fiber. A stable average power of 30 W of the pulsed 70-ns 100-kHz laser radiation in a near Gaussian beam was reached by means of the two-stage amplifier based on Yb3+-doped fibers with an enlarged mode field diameter (14 μm). The amplifier was pumped by λ = 975 nm CW multimode laser diodes with a maximum average power of 42 W.

High-beam quality, high-efficiency laser based on fiber with heavily Yb(3+)-doped phosphate core and silica cladding.

PubMed

Egorova, O N; Semjonov, S L; Medvedkov, O I; Astapovich, M S; Okhrimchuk, A G; Galagan, B I; Denker, B I; Sverchkov, S E; Dianov, E M

2015-08-15

We have fabricated and tested a composite fiber with an Yb(3+)-doped phosphate glass core and silica cladding. Oscillation with a slope efficiency of 74% was achieved using core pumping at 976 nm with fiber lengths of 48-90 mm in a simple laser configuration, where the cavity was formed by a high-reflectivity Bragg grating and the cleaved fiber end. The measured M(2) factors were as low as 1.05-1.22 even though the fiber was multimode at the lasing wavelength.

Single frequency 1560nm Er:Yb fiber amplifier with 207W output power and 50.5% slope efficiency

NASA Astrophysics Data System (ADS)

Creeden, Daniel; Pretorius, Herman; Limongelli, Julia; Setzler, Scott D.

2016-03-01

High power fiber lasers/amplifiers in the 1550nm spectral region have not scaled as rapidly as Yb-, Tm-, or Ho-doped fibers. This is primarily due to the low gain of the erbium ion. To overcome the low pump absorption, Yb is typically added as a sensitizer. Although this helps the pump absorption, it also creates a problem with parasitic lasing of the Yb ions under strong pumping conditions, which generally limits output power. Other pump schemes have shown high efficiency through resonant pumping of erbium only without the need for Yb as a sensitizer [1-2]. Although this can enable higher power scaling due to a decrease in the thermal loading, resonant pumping methods require long fiber lengths due to pump bleaching, which may limit the power scaling which can be achieved for single frequency output. By using an Er:Yb fiber and pumping in the minima of the Yb pump absorption at 940nm, we have been able to simultaneously generate high power, single frequency output at 1560nm while suppressing the 1-micron ASE and enabling higher efficiency compared to pumping at the absorption peak at 976nm. We have demonstrated single frequency amplification (540Hz linewidth) to 207W average output power with 49.3% optical efficiency (50.5% slope efficiency) in an LMA Er:Yb fiber. We believe this is the highest reported efficiency from a high power 9XXnm pumped Er:Yb-doped fiber amplifier. This is significantly more efficient that the best-reported efficiency for high power Er:Yb doped fibers, which, to-date, has been limited to ~41% slope efficiency [3].

Diode-pumped 1.5-1.6 μm laser operation in Er³⁺ doped YbAl₃(BO₃)₄ microchip.

PubMed

Chen, Yujin; Lin, Yanfu; Zou, Yuqi; Huang, Jianhua; Gong, Xinghong; Luo, Zundu; Huang, Yidong

2014-06-02

Er3+ doped YbAl3(BO3)4 crystal with large absorption coefficient of 184 cm(-1) at pump wavelength of 976 nm is a promising microchip gain medium of 1.5-1.6 μm laser. End-pumped by a 976 nm diode laser, 1.5-1.6 μm continuous-wave laser with maximum output power of 220 mW and slope efficiency of 8.1% was obtained at incident pump power of 4.54 W in a c-cut 200-μm-thick Er:YbAl3(BO3)4 microchip. When a Co2+:Mg0.4Al2.4O4 crystal was used as the saturable absorber, 1521 nm passively Q-switched pulse laser with about 0.19 μJ energy, 265 ns duration, and 96 kHz repetition rate was realized.

Photon up-conversion production in Tb{sup 3+}–Yb{sup 3+} co-doped CaF{sub 2} phosphors prepared by combustion synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rakov, Nikifor, E-mail: nikifor.gomez@univasf.edu.br; Guimarães, Renato B.; Maciel, Glauco S., E-mail: glauco@if.uff.br

2016-02-15

Graphical abstract: Up-conversion luminescence from Tb{sup 3+} obtained by energy transfer from Yb{sup 3+} pairs in CaF{sub 2} powder prepared by combustion synthesis. - Highlights: • Calcium fluoride (CaF{sub 2}) powders were prepared by combustion synthesis. • Rare-earth ions doped in this material were found in interstitial sites. • Cooperative up-conversion was observed in Tb{sup 3+}:Yb{sup 3+}:CaF{sub 2} powder. • Energy transfer between Tb{sup 3+} and pairs of Yb{sup 3+} was analyzed using rate equations. - Abstract: Calcium fluoride (CaF{sub 2}) crystalline powders were successfully prepared by the combustion synthesis method. The powder material containing luminescent rare-earth ions, more specificallymore » terbium (Tb{sup 3+}) and ytterbium (Yb{sup 3+}), was studied by X-ray diffraction, scanning electronic microscopy and optical spectroscopy. These ions are allocated in charge compensated interstitial positions of tetragonal (C{sub 4v}) and trigonal (C{sub 3v}) symmetry sites of the cubic (O{sub h}) CaF{sub 2} lattice. Up-conversion (UC) luminescence in Tb{sup 3+} was achieved using a low power diode laser operating at 975 nm. Tb{sup 3+} is insensitive to near-infrared radiation but UC can be achieved via energy transfer from pairs of Yb{sup 3+} ions to Tb{sup 3+} ions. The UC luminescence dynamics of Tb{sup 3+} was used to study the energy transfer mechanism.« less

High-Speed Terahertz Waveform Measurement for Intense Terahertz Light Using 100-kHz Yb-Doped Fiber Laser.

PubMed

Tsubouchi, Masaaki; Nagashima, Keisuke

2018-06-14

We demonstrate a high-speed terahertz (THz) waveform measurement system for intense THz light with a scan rate of 100 Hz. To realize the high scan rate, a loudspeaker vibrating at 50 Hz is employed to scan the delay time between THz light and electro-optic sampling light. Because the fast scan system requires a high data sampling rate, we develop an Yb-doped fiber laser with a repetition rate of 100 kHz optimized for effective THz light generation with the output electric field of 1 kV/cm. The present system drastically reduces the measurement time of the THz waveform from several minutes to 10 ms.

High brightness InP micropillars grown on silicon with Fermi level splitting larger than 1 eV.

PubMed

Tran, Thai-Truong D; Sun, Hao; Ng, Kar Wei; Ren, Fan; Li, Kun; Lu, Fanglu; Yablonovitch, Eli; Chang-Hasnain, Constance J

2014-06-11

The growth of III-V nanowires on silicon is a promising approach for low-cost, large-scale III-V photovoltaics. However, performances of III-V nanowire solar cells have not yet been as good as their bulk counterparts, as nanostructured light absorbers are fundamentally challenged by enhanced minority carriers surface recombination rates. The resulting nonradiative losses lead to significant reductions in the external spontaneous emission quantum yield, which, in turn, manifest as penalties in the open-circuit voltage. In this work, calibrated photoluminescence measurements are utilized to construct equivalent voltage-current characteristics relating illumination intensities to Fermi level splitting ΔF inside InP microillars. Under 1 sun, we show that splitting can exceed ΔF ∼ 0.90 eV in undoped pillars. This value can be increased to values of ΔF ∼ 0.95 eV by cleaning pillar surfaces in acidic etchants. Pillars with nanotextured surfaces can yield splitting of ΔF ∼ 0.90 eV, even though they exhibit high densities of stacking faults. Finally, by introducing n-dopants, ΔF of 1.07 eV can be achieved due to a wider bandgap energy in n-doped wurzite InP, the higher brightness of doped materials, and the extraordinarily low surface recombination velocity of InP. This is the highest reported value for InP materials grown on a silicon substrate. These results provide further evidence that InP micropillars on silicon could be a promising material for low-cost, large-scale solar cells with high efficiency.

Effect of Yb substitution on room temperature magnetic and dielectric properties of bismuth ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Remya, K. P.; Amirthapandian, S.; Manivel Raja, M.; Viswanathan, C.; Ponpandian, N.

2016-10-01

Effect of the Yb dopant on the structural, magnetic, and electrical properties of the multiferroic BiFeO3 have been studied. The structural properties of sol-gel derived Bi1-xYbxFeO3 (x = 0.0, 0.1, and 0.2) nanoparticles reveal the formation of a rhombohedrally distorted perovskite in XRD and a reduction in the average grain size have been observed with an increase in the Yb concentration. Microstructural studies exhibited the formation of sphere like morphology with decreasing particle size with increase in the dopant concentration. The effective doping also resulted in larger magnetization as well as coercivity with the maximum of 257 Oe and 1.76 emu/g in the Bi0.8Yb0.2FeO3 nanoparticles. Ferroelectric as well as dielectric properties of the nanoparticles were also improved on doping. The best results were obtained for the BiFeO3 nanoparticles having Yb concentration x = 0.2.

Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

NASA Astrophysics Data System (ADS)

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-01

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

Yb3+-doped cadmium molybdato-tungstate single crystal - Its structural, optical, magnetic and transport properties

NASA Astrophysics Data System (ADS)

Groń, T.; Tomaszewicz, E.; Berkowski, M.; Głowacki, M.; Oboz, M.; Kusz, J.; Sawicki, B.; Kukuła, Z.; Duda, H.

2018-06-01

Single crystal of new cadmium and ytterbium molybdato-tungstate (Cd0.9706⎕0.0098Yb0.0196(MoO4)0.9706(WO4)0.0294, where ⎕ denotes cationic vacancies) has been successfully grown by the Czochralski method in air and under 1 MPa. X-ray crystallographic analysis reveals that the as-grown single crystal belongs to a scheelite-type structure (a = b = 5.15539(12) and c = 11.1919(3) Å, space group I41/a), in which Yb3+ ions do not show long-range order and are randomly distributed in the unit cell, substituting the Cd2+ ones. The as-grown single crystal does not show anisotropy of optical properties, i.e. its direct band gap reaches Eg = 1.76 or 1.75 eV along (100) and (001) crystallographic directions, respectively. The single crystal exhibits paramagnetic state with short-range antiferromagnetic and long-range ferrimagnetic interactions, a magnetization with zero coercivity and, a remanence that is almost a universal function of H/T, characterizing superparamagnetic-like behaviour. Electrical studies of the new ytterbium-doped cadmium molybdato-tungstate single crystal show a relatively small dielectric constant (εr<12), large lossiness of Joule-Lenz type observed at low frequencies as well as nonlinear I-V characteristics of Schottky or Maxwell-Wagner type.

When is an INP not an INP?

NASA Astrophysics Data System (ADS)

Simpson, Emma; Connolly, Paul; McFiggans, Gordon

2016-04-01

Processes such as precipitation and radiation depend on the concentration and size of different hydrometeors within clouds therefore it is important to accurately predict them in weather and climate models. A large fraction of clouds present in our atmosphere are mixed phase; contain both liquid and ice particles. The number of drops and ice crystals present in mixed phase clouds strongly depends on the size distribution of aerosols. Cloud condensation nuclei (CCN), a subset of atmospheric aerosol particles, are required for liquid drops to form in the atmosphere. These particles are ubiquitous in the atmosphere. To nucleate ice particles in mixed phase clouds ice nucleating particles (INP) are required. These particles are rarer than CCN. Here we investigate the case where CCN and INPs are in direct competition with each other for water vapour within a cloud. Focusing on the immersion and condensation modes of freezing (where an INP must be immersed within a liquid drop before it can freeze) we show that the presence of CCN can suppress the formation of ice. CCN are more hydrophilic than IN and as such are better able to compete for water vapour than, typically insoluble, INPs. Therefore water is more likely to condense onto a CCN than INP, leaving the INP without enough condensed water on it to be able to freeze in the immersion or condensation mode. The magnitude of this suppression effect strongly depends on a currently unconstrained quantity. Here we refer to this quantity as the critical mass of condensed water required for freezing, Mwc. Mwc is the threshold amount of water that must be condensed onto a INP before it can freeze in the immersion or condensation mode. Using the detailed cloud parcel model, Aerosol-Cloud-Precipiation-Interaction Model (ACPIM), developed at the University of Manchester we show that if only a small amount of water is required for freezing there is little suppression effect and if a large amount of water is required there is a

Up-conversion monodispersed spheres of NaYF4:Yb3+/Er3+: green and red emission tailoring mediated by heating temperature, and greatly enhanced luminescence by Mn2+ doping.

PubMed

Zhu, Qi; Song, Caiyun; Li, Xiaodong; Sun, Xudong; Li, Ji-Guang

2018-04-09

Submicron sized, monodispersed spheres of Mn2+, Yb3+/Er3+ and Mn2+/Yb3+/Er3+ doped α-NaYF4 were easily autoclaved from mixed solutions of the component nitrates and ammonium fluoride (NH4F), in the presence of EDTA-2Na. Detailed characterizations of the resultant phosphors were obtained using XRD, Raman spectroscopy, FE-SEM, HR-TEM, STEM, PLE/PL spectroscopy, and fluorescence decay analysis. Finer structure and better crystal perfection was observed at a higher calcination temperature, and the spherical shape and excellent dispersion of the original particles was retained at temperatures up to 600 °C. Under the 980 nm infrared excitation, the Yb3+/Er3+-doped sample (calcined at 400 °C) exhibits a stronger green emission centered at ∼524 nm (2H11/2 → 4I15/2 transition of Er3+) and a weaker red emission centered at ∼657 nm (4F9/2 → 4I15/2 transition of Er3+). A 200 °C increase in the temperature from 400 °C to 600 °C resulted in the dominant red emission originating from the 4F9/2 → 4I15/2 transition of Er3+, instead of the previously dominant green one. Mn2+ doping induced a remarkable more enhanced intensity at ∼657 nm and ∼667 nm (red emission area) than that at ∼524 nm and ∼546 nm (green emission area), because of the non-radiative energy transfer between Mn2+ and Er3+. However, a poor thermal stability was induced by Mn2+ doping. The observed upconversion luminescence of the samples calcined at 400 °C and 600 °C followed the two photon process and the four photon process, respectively.

Bifunction in Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} glasses prepared by aerodynamic levitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Minghui; University of Chinese Academy of Sciences, Beijing 100039; Yu, Jianding

2013-11-15

Graphical abstract: - Highlights: • Novel BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} based glasses have been prepared by aerodynamic levitation. • The obtained glasses show high thermal stability with T{sub g} = 763.3 °C. • Er{sup 3+}/Yb{sup 3+} co-doped glasses show strong upconversion based on a two-photon process. • Red emission is stronger than green emissions for EBT by high Yb{sup 3+} concentration. • Magnetic ions are paramagnetic and the distribution is homogeneous in the glasses. - Abstract: Novel Er{sup 3+}/Yb{sup 3+} co-doped BaTi{sub 2}O{sub 5}–Gd{sub 2}O{sub 3} spherical glasses have been fabricated by aerodynamic levitation method. The thermal stability, upconversionmore » luminescence, and magnetic properties of the present glass have been studied. The glasses show high thermal stability with 763.3 °C of the onset temperature of the glass transition. Red and green emissions centered at 671 nm, 548 nm and 535 nm are obtained at 980 nm excitation. The upconversion is based on a two-photon process by energy transfer, excited-state absorption, and energy back transfer. Yb{sup 3+} ions are more than Er{sup 3+} ions in the glass, resulting in efficient energy back transfer from Er{sup 3+} to Yb{sup 3+}. So the red emission is stronger than the green emissions. Magnetization curves indicate that magnetic rare earth ions are paramagnetic and the distribution is homogeneous and random in the glass matrix. Aerodynamic levitation method is an efficient way to prepare glasses with homogeneous rare earth ions.« less

Spin-flop and magnetodielectric reversal in Yb substituted GdMnO3

NASA Astrophysics Data System (ADS)

Pal, A.; Prellier, W.; Murugavel, P.

2018-03-01

The evolution of various spin structures in Yb doped GdMnO3 distorted orthorhombic perovskite system was investigated from their magnetic, dielectric and magnetodielectric characteristics. The Gd1-x Yb x MnO3 (0  ⩽  x  ⩽  0.15) revealed an enhanced magnetodielectric coupling when their magnetic structure is guided from ab to the bc-cycloidal spin structure upon Yb doping. The compounds exhibit magnetic field and temperature controlled spin-flop from c to a-axis. Additionally, magnetodielectric reversal is observed for the x  =  0.1 sample which depends on both magnetic field and temperature. The resultant correlation between magnetic and electric orderings is discussed in the frame of symmetric and antisymmetric exchange interaction models. These findings provide further insight in understanding the magnetoelectric materials and importantly show a way to tune the magnetic and magnetodielectric properties towards better application potential.

Influence of F- on stark splitting of Yb3+ and the thermal expansion of silica glass

NASA Astrophysics Data System (ADS)

Cao, Yabin; Chen, Si; Shao, Chongyun; Yu, Chunlei

2018-06-01

A local phosphate/fluoride environment of Yb3+ was created in silica glass using a multi-step method. The influence of F- on the Stark splitting of Yb3+ in Al3+/P5+/F- co-doped silica glass was studied at room-temperature, in addition to its effect on the thermal expansion performance of the glass matrix. The results indicate that Yb3+ ions in Al3+/P5+/F- co-doped silica glass have a larger Stark splitting energy of 2F7/2 compared to Al3+/P5+ co-doped silica glass. Moreover, a larger integrated absorption cross-section (34.58 pm2 × nm), stimulated emission cross-section (0.63 pm2), and better thermal expansion performance (1.3062 × 10-6 K- at 100 °C) are achieved in Al3+/P5+/F- co-doped silica glass. Finally, different function mechanisms of F- in silica and phosphate glasses were analyzed and the F-Si bond was used to explain the results in silica glass. The combination of low refractive index, large Stark splitting energy of 2F7/2, and small thermal expansion makes Al3+/P5+/F- co-doped silica glass a preferred material for large mode area fibers for high-power laser applications.

Colour emission tunability in Ho3+-Tm3+-Yb3+ co-doped Y2O3 upconverted phosphor

NASA Astrophysics Data System (ADS)

Pandey, Anurag; Rai, Vineet Kumar

2012-12-01

The frequency upconversion (UC) emission throughout the visible region from the Y2O3:Ho3+-Tm3+-Yb3+ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980 nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the 1G4 → 3H6 (Tm3+) and 5F3 → 5I8 (Ho3+) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.

Realization and optimization of a 1 ns pulsewidth multi-stage 250 kW peak power monolithic Yb doped fiber amplifier at 1064 nm

NASA Astrophysics Data System (ADS)

Morasse, Bertrand; Plourde, Estéban

2017-02-01

We present a simple way to achieve and optimize hundreds of kW peak power pulsed output using a monolithic amplifier chain based on solid core double cladding fiber tightly packaged. A fiber pigtailed current driven diode is used to produce nanosecond pulses at 1064 nm. We present how to optimize the use of Fabry-Perot versus DFB type diode along with the proper wavelength locking using a fiber Bragg grating. The optimization of the two pre-amplifiers with respect to the pump wavelength and Yb inversions is presented. We explain how to manage ASE using core and cladding pumping and by using single pass and double pass amplifier. ASE rejection within the Yb fiber itself and with the use of bandpass filter is discussed. Maximizing the amplifier conversion efficiency with regards to the fiber parameters, glass matrix and signal wavelength is described in details. We present how to achieve high peak power at the power amplifier stage using large core/cladding diameter ratio highly doped Yb fibers pumped at 975 nm. The effect of pump bleaching on the effective Yb fiber length is analyzed carefully. We demonstrate that counter-pumping brings little advantage in very short length amplifier. Dealing with the self-pulsation limit of stimulated Brillouin scattering is presented with the adjustment of the seed pulsewidth and linewidth. Future prospects for doubling the output peak power are discussed.

Isoelectronic co-doping

DOEpatents

Mascarenhas, Angelo

2004-11-09

Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

Radiation effects on p+n InP junctions grown by MOCVD

NASA Technical Reports Server (NTRS)

Messenger, Scott R.; Walters, Robert J.; Panunto, M. J.; Summers, Geoffrey P.

1994-01-01

The superior radiation resistance of InP over other solar cell materials such as Si or GaAs has prompted the development of InP cells for space applications. The early research on radiation effects in InP was performed by Yamaguchi and co-workers who showed that, in diffused p-InP junctions, radiation-induced defects were readily annealed both thermally and by injection, which was accompanied by significant cell recovery. More recent research efforts have been made using p-InP grown by metalorganic chemical vapor deposition (MOCVD). While similar deep level transient spectroscopy (DLTS) results were found for radiation induced defects in these cells and in diffused junctions, significant differences existed in the annealing characteristics. After injection annealing at room temperature, Yamaguchi noticed an almost complete recovery of the photovoltaic parameters, while the MOCVD samples showed only minimal annealing. In searching for an explanation of the different annealing behavior of diffused junctions and those grown by MOCVD, several possibilities have been considered. One possibility is the difference in the emitter structure. The diffused junctions have S-doped graded emitters with widths of approximately 0.3 micrometers, while the MOCVD emitters are often doped with Si and have widths of approximately 300A (0.03 micrometers). The difference in the emitter thickness can have important effects, e.g. a larger fraction of the total photocurrent is generated in the n-type material for thicker emitters. Therefore the properties of the n-InP material may explain the difference in the observed overall annealing behavior of the cells.

5  W output power from a double-clad hybrid fiber with Yb-doped phosphate core and silicate cladding.

PubMed

Wang, Longfei; He, Dongbing; Zhang, Lei; Yu, Chunlei; Feng, Suya; Wang, Meng; Chen, Danping; Hu, Lili

2017-08-01

For the first time, to the best of our knowledge, we report on the realization of a laser from a Yb-doped phosphate core/silicate cladding double-clad hybrid fiber. 5 W output power was extracted with 14.6% slope efficiency and a laser spectrum of a 1027 nm central wavelength from a 20 cm long single-mode fiber with a ∼10  μm core diameter in a 20%-4% laser cavity. The laser efficiency can be significantly enhanced by correspondingly adjusting and optimizing the laser oscillator.

Investigating the evolution of local structure around Er and Yb in ZnO:Er and ZnO:Er, Yb on annealing using X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Anjana, R.; Jayaraj, M. K.; Yadav, A. K.; Jha, S. N.; Bhattacharyya, D.

2018-04-01

The local structure around Er and Yb centre in ZnO favouring upconversion luminescence was studied using EXAFS (Extended X-ray absorption fine structure spectroscopy). Due to the ionic radii difference between Zn and Er, Yb ions, the dopants cannot replace Zn in the ZnO lattice properly. Er2O3 and Yb2O3 impurity phases are formed at the grain boundaries of ZnO. It is found that the local structure around the Er centre in ZnO is modified on annealing in air. The symmetry around both erbium and ytterbium reduces with increase in annealing temperature. Symmetry reduction will favour the intra-4f transition and the energy transitions causing upconversion luminescence. By fitting the EXAFS data with theoretically simulated data, it is found that the Er centre forms a local structure similar to C4ν symmetry which is a distorted octahedron. On annealing the sample to 1200 °C, all the erbium centres are transformed to C4ν symmetry causing enhanced upconversion emission. Yb centre has also been modified on annealing. The decrease in co-ordination number with annealing temperature will decrease the symmetry and increase the near infrared absorption cross section. The decrease in symmetry around both the erbium and ytterbium centre and formation of C4ν symmetry around Er centre is the reason behind the activation of upconversion luminescence with high temperature annealing in both Er doped and Er, Yb co-doped ZnO samples. The study will be useful for the synthesis of high efficiency upconversion materials.

Sub-MW peak power diffraction-limited chirped-pulse monolithic Yb-doped tapered fiber amplifier.

PubMed

Bobkov, Konstantin; Andrianov, Alexey; Koptev, Maxim; Muravyev, Sergey; Levchenko, Andrei; Velmiskin, Vladimir; Aleshkina, Svetlana; Semjonov, Sergey; Lipatov, Denis; Guryanov, Alexey; Kim, Arkady; Likhachev, Mikhail

2017-10-30

We demonstrate a novel amplification regime in a counter-pumped, relatively long (2 meters), large mode area, highly Yb-doped and polarization-maintaining tapered fiber, which offers a high peak power directly from the amplifier. The main feature of this regime is that the amplifying signal propagates through a thin part of the tapered fiber without amplification and experiences an extremely high gain in the thick part of the tapered fiber, where most of the pump power is absorbed. In this regime, we have demonstrated 8 ps pulse amplification to a peak power of up to 0.76 MW, which is limited by appearance of stimulated Raman scattering. In the same regime, 28 ps chirped pulses are amplified to a peak power of 0.35 MW directly from the amplifier and then compressed with 70% efficiency to 315 ± 10 fs, corresponding to an estimated peak power of 22 MW.

Diode-Pumped Narrow Linewidth Multi-kW Metalized Yb Fiber Amplifier

DTIC Science & Technology

2016-10-01

multi-kW Yb fiber amplifier in a bi-directional pumping configuration. Each pump outputs 2 kW in a 200 µm, 0.2 NA multi-mode fiber. Gold -coated...multi-mode instability, with 90% O-O efficiency 12 GHz Linewidth and M2 < 1.15. OCIS codes: (140.3510) Lasers , fiber; (140.3615) Lasers , ytterbium...060.2430) Fibers, single-mode. 1. INTRODUCTION Yb-doped fiber laser has experienced exponential growth over the past decade. The output power

Rapid thermal anneal in InP, GaAs and GaAs/GaAlAs

NASA Astrophysics Data System (ADS)

Descouts, B.; Duhamel, N.; Godefroy, S.; Krauz, P.

Ion implantation in semiconductors provides a doping technique with several advantages over more conventional doping methods and is now extensively used for device applications, e.g. field effect transistors (MESFET GaAs, MIS (InP), GaAs/GaAlAs heterojunction bipolar transistors (HBT). Because of the lattice disorder produced by the implantation, the dopant must be made electrically active by a postimplant anneal. As the device performances are very dependent on its electrical characteristics, the anneal is a very important stage of the process. Rapid anneal is known to provide less exodiffusion and less induffusion of impurities compared to conventional furnace anneal, so this technique has been used in this work to activate an n-type dopant (Si) in InP and a p-type dopant (Mg) in GaAs and GaAs/GaAIAs. These two ions have been chosen to realize implanted MIS InP and the base contacts for GaAs/GaAlAs HBTs. The experimental conditions to obtain the maximum electrical activity in these two cases will be detailed. For example, although we have not been able to obtain a flat profile in Mg + implanted GaAs/GaAlAs heterostructure by conventional thermal anneal, rapid thermal anneal gives a flat hole profile over a depth of 0.5 μm with a concentration of 1 x 10 19 cm -3.

Ytterbium-doped borate fluoride laser crystals and lasers

DOEpatents

Schaffers, Kathleen I.; DeLoach, Laura D.; Payne, Stephen A.; Keszler, Douglas A.

1997-01-01

A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

Enhanced frequency upconversion in Er3+-Yb3+ codoped heavy metal oxides based tellurite glasses.

PubMed

Azam, Mohd; Rai, Vineet Kumar

2018-01-24

The spectroscopic investigations on the Er 3+ /Yb 3+ ions doped/codoped TeO 2 -ZnO (TZ), TeO 2 -ZnO-WO 3 (TZW) and TeO 2 -ZnO-WO 3 -TiO 2 (TZWTi) heavy metal oxide (HMO) glasses have been made. The absorption, photoluminescence, decay curve and Judd-Ofelt analysis have been performed to optimise the optical properties of the Er 3+ /Yb 3+ ions. The effect of incorporation of HMOs like WO 3 and TiO 2 in the Er 3+ /Yb 3+ doped/codoped TZ glass on its optical properties have been investigated. The enhancement in upconversion emission intensity has been explained on the basis of efficient energy transfer and inhomogeneous local field generation around the rare earth ions. The spectroscopic quality factor, absorption and stimulated emission cross-sections, optical gain, quantum efficiency (∼17.53%), energy transfer efficiency (∼61.64%), colour purity (∼94.7%) and ionic nature of the bonding have been determined. The Er 3+ -Yb 3+ -TZWTi glass can be used in visible lasers, yellowish green optical devices and home appliances.

Investigation of Upconversion, downshifting and quantum –cutting behavior of Eu3+, Yb3+, Bi3+ co-doped LaNbO4 phosphor as a spectral conversion material

NASA Astrophysics Data System (ADS)

Dwivedi, A.; Mishra, K.; Rai, S. B.

2018-06-01

This work presents the spectral conversion characteristics [upconversion (UC), downshifting (DS) and quantum–cutting (QC) optical processes] of Eu3+, Yb3+ and Bi3+ co-doped LaNbO4 (LBO) phosphor samples synthesized by solid state reaction technique. The crystal structure and the pure phase formation have been confirmed by x-ray diffraction (XRD) measurements. The surface morphology and particle size are studied by scanning electron microscopy (SEM). The rarely observed intense red UC emission from Eu3+ ion has been successfully obtained in Eu3+/Yb3+ co-doped LaNbO4 phosphor (on excitation with 980 nm) by optimizing the concentrations of Eu3+ and Yb3+ ions. The downshifting (DS) behavior has been studied by photoluminescence (PL) measurements on excitation with 265 nm wavelength from a Xe lamp source. A broad blue emission in the region 300–550 nm with its maximum ∼415 nm due to charge transfer band (CTB) of the host and large number of sharp peaks due to f-f transitions of Eu3+ ion have been observed. The energy transfer has been observed from (NbO4)3‑ to Eu3+ ion and the fluorescence emission has been optimized by varying the concentration of Eu3+ ion. An intense red emission has also been observed corresponding to 5D0 → 7F2 transition of Eu3+ ion at 611 nm in LBO: 0.09Eu3+ phosphor on excitation with 394 nm. The luminescence properties of Eu3+ ion are enhanced further through the sensitization effect of Bi3+ ion. The near infra-red (NIR) quantum cutting (QC) behavior due to Yb3+ ion has been monitored on excitation with 265 as well as 394 nm. The NIR QC is observed due to 2F5/2 → 2F7/2 transition of Yb3+ ion via co-operative energy transfer (CET) process from (NbO4)3‑ as well as Eu3+ ions to Yb3+ ion. This multimodal behavior (UC, DS and QC) makes this a promising phosphor material for multi-purpose spectral converter.

A femtosecond Yb-doped fiber laser with generalized vector vortex beams output (Conference Presentation)

NASA Astrophysics Data System (ADS)

Huo, Tiancheng; Qi, Li; Zhang, Buyun; Chen, Zhongping

2017-03-01

Light carries both spin and orbital angular momentum (OAM) and the superpositions of these two dynamical properties have found many applications. Many techniques exist to create such light sources but none allow their creation at the femtosecond fiber laser. Here we report on a novel mode-locked Ytterbium-doped fiber laser that generates femtosecond pulses with generalized vector vortex states. The controlled generation of such pulses such as azimuthally and radially polarized light with definite orbital angular momentum modes are demonstrated. A unidirectional ring cavity constructed with the Yb-doped fiber placed at the end of the fiber section to reduces unnecessary nonlinear effects is employed for self-starting operation. Pairs of diffraction gratings are used for compensating the normal group velocity dispersion of the fiber and other elements. Mode-locked operation is achieved based on nonlinear polarization evolution, which is mainly implemented with the single mode fiber, the bulk wave plates and the variable spiral plates (q-plate with topological charge q=0.5). The conversion from spin angular momentum to the OAM and reverse inside the laser cavity are realized by means of a quarter-wave plate and a q-plate so that the polarization control was mapped to OAM mode control. The fiber laser is diode pumped by a wavelength-division multiplexing coupler, which leads to excellent stability and portability.

Spectroscopic investigation of zinc tellurite glasses doped with Yb(3+) and Er(3+) ions.

PubMed

Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

2016-08-05

This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80-x-y) TeO2+(0.20) ZnO+xEr2O3+yYb2O3 (x=0, y=0; x=0.004, y=0; x=0, y=0.05 and x=0.004, y=0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er(3+) glasses as erbium doped fiber amplifiers at 1.55μm in infrared emission region. Copyright © 2016 Elsevier B.V. All rights reserved.

Atomic frequency reference at 1033 nm for ytterbium (Yb)-doped fiber lasers and applications exploiting a rubidium (Rb) 5S_1/2 to 4D_5/2 one-colour two-photon transition

NASA Astrophysics Data System (ADS)

Roy, Ritayan; Condylis, Paul C.; Johnathan, Yik Jinen; Hessmo, Björn

2017-04-01

We demonstrate a two-photon transition of rubidium (Rb) atoms from the ground state (5$S_{1/2}$) to the excited state (4$D_{5/2}$), using a home-built ytterbium (Yb)-doped fiber amplifier at 1033 nm. This is the first demonstration of an atomic frequency reference at 1033 nm as well as of a one-colour two-photon transition for the above energy levels. A simple optical setup is presented for the two-photon transition fluorescence spectroscopy, which is useful for frequency stabilization for a broad class of lasers. This spectroscopy has potential applications in the fiber laser industry as a frequency reference, particularly for the Yb-doped fiber lasers. This two-photon transition also has applications in atomic physics as a background- free high- resolution atom detection and for quantum communication, which is outlined in this article.

Spectroscopy of high index contrast Yb:Ta2O5 waveguides for lasing applications

NASA Astrophysics Data System (ADS)

Aghajani, A.; Murugan, G. S.; Sessions, N. P.; Apostolopoulos, V.; Wilkinson, J. S.

2015-06-01

Ytterbium-doped waveguides are required for compact integrated lasers and Yb- doped Ta2O5 is a promising candidate material. The design, fabrication and spectroscopic characterisation of Yb:Ta2O5 rib waveguides are described. The peak absorption cross-section was measured to be 2.75×10-20 cm2 at 975 nm. The emission spectrum was found to have a fluorescence emission peak at a wavelength of 976 nm with a peak cross-section of 2.9×10-20 cm2 and a second broad fluorescence band spanning from 990 nm to 1090 nm. The excited- state life time was measured to be 260 μs.

Monolithic diffraction-limited 976-nm laser based on saddle-shaped photo darkening-free Yb-doped fiber

NASA Astrophysics Data System (ADS)

Aleshkina, Svetlana S.; Lipatov, Denis S.; Levchenko, Andrei E.; Medvedkov, Oleg I.; Bobkov, Konstantin K.; Bubnov, Mikhail M.; Guryanov, Alexei N.; Likhachev, Mikhail E.

2018-02-01

Monolithic 976 nm laser design based on a newly developed saddle-shaped Yb-doped fiber has been proposed. The fiber has central single-mode part with core diameter of about 12 μm and ultra-thin square-shaped clad with side of about 42x42 μm. At the both ends of the saddle-shaped fiber the core and the clad sizes were adiabatically increased up to 20/(70x70) μm and the fiber could be spliced with standard (80..125 μm clad) passive fibers using commercially available equipment. Single-mode laser at 976 nm based on the developed fiber has been fabricated and photodarkening-free operation with output power of 10.6 W, which is the record high for all-fiber laser schemes, has been demonstrated.

Visible upconversion emission and non-radiative direct Yb 3+ to Er 3+ energy transfer processes in nanocrystalline ZrO 2:Yb 3+,Er 3+

NASA Astrophysics Data System (ADS)

Diaz-Torres, L. A.; Meza, O.; Solis, D.; Salas, P.; De la Rosa, E.

2011-06-01

Wide band gap Yb 3+ and Er 3+ codoped ZrO 2 nanocrystals have been synthesized by a modified sol-gel method. Under 967 nm excitation strong green and red upconversion emission is observed for several Er 3+ to Yb 3+ ions concentration ratios. A simple microscopic rate equation model is used to study the effects of non-radiative direct Yb 3+ to Er 3+ energy transfer processes on the visible and near infrared fluorescence decay trends of both Er 3+ and Yb 3+ ions. The microscopic rate equation model takes into account the crystalline phase as well as the size of nanocrystals. Nanocrystals phase and size were estimated from XRD patterns. The rate equation model succeeds to fit simultaneously all visible and near infrared fluorescence decay profiles. The dipole-dipole interaction parameters that drive the non-radiative energy transfer processes depend on doping concentration due to crystallite phase changes. In addition the non-radiative relaxation rate ( 4I11/2→ 4I13/2) is found to be greater than that estimated by the Judd-Ofelt parameters due to the action of surface impurities. Results suggest that non-radiative direct Yb 3+ to Er 3+ energy transfer processes in ZrO 2:Yb,Er are extremely efficient.

Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

PubMed

Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

2014-11-17

We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance.

Wavelength adjustability of frequency conversion light of Yb-doped fiber laser based on FBGs

NASA Astrophysics Data System (ADS)

Dobashi, Kazuma; Tomihari, Yasuhiro; Imai, Koichi; Hirohashi, Junji; Makio, Satoshi

2018-02-01

We focused on wavelength conversion of simple and compact CW Yb-Doped fiber laser based on FBGs with wavelength adjustable function. By controlling temperatures of FBGs in fiber laser, it was possible to tune oscillated wavelength from 1064.101 nm to 1064.414 nm with more than 20 W in CW operation mode. Based on this fundamental light, frequency converted light (SHG and THG) were generated by utilizing two PP:Mg-SLT devises. We obtained more than 3 W of SHG light with tuning range of 150 pm and more than 35 mW of THG with tuning range of 100 pm. By selecting FBG grating and QPM grating properly, we can realize adjustable wavelength laser with the same scheme from 1040 nm to 1090 nm and their SHG/THG. With this combination of FBG based fiber laser and QPM devices, it is possible to tune the wavelength just by temperature tuning without any changes of beam shape and beam pointing.

Ytterbium-doped borate fluoride laser crystals and lasers

DOEpatents

Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

1997-10-14

A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

Structure and up-conversion luminescence in sol-gel derived Er 3+-Yb 3+ co-doped SiO 2:PbF 2 nano-glass-ceramics

NASA Astrophysics Data System (ADS)

del-Castillo, J.; Yanes, A. C.; Méndez-Ramos, J.; Tikhomirov, V. K.; Rodríguez, V. D.

2009-11-01

Transparent oxyfluoride nano-glass-ceramics 90(SiO 2)10(PbF 2) co-doped with 0.3 Yb 3+ and 0.1 Er 3+ (mol%) have been prepared by thermal treatment of precursor sol-gel glasses. X-ray diffraction and high resolution transmission electron microscopy analysis pointed out a precipitation of cubic β-PbF 2 nanocrystals of certain diameter in nano-glass-ceramics varying from 10 to 20 nm depending on heat treatment conditions. The incorporation of Yb 3+ and Er 3+ dopants in these nanocrystals has been confirmed by signatures of luminescence spectroscopy. Up-conversion luminescence pumped at 980 nm has been detected. Colour tuneability of up-conversion luminescence varying pump power has been analyzed in terms of standard chromaticity diagram. This tuneability opens applications for up-conversion phosphors and three-dimensional optical recording.

Evidence of dissipative solitons in Yb³⁺:CaYAlO₄.

PubMed

Tan, W D; Tang, D Y; Xu, C W; Zhang, J; Xu, X D; Li, D Z; Xu, J

2011-09-12

Operation of an end-pumped Yb³⁺:CaYAlO₄ laser operating in the positive dispersion regime is experimentally investigated. The laser emitted strongly chirped pulses with extremely steep spectral edges, resembling the characteristics of dissipative solitons observed in fiber lasers. The results show that dissipative soliton emission constitutes another operating regime for mode locked Yb³⁺-doped solid state lasers, which can be explored for the generation of stable large energy femtosecond pulses.

Yb3+-doped rod-type amplifiers with local adiabatic tapers for peak power scaling and beam quality improvement

NASA Astrophysics Data System (ADS)

Zhu, Yuan; Eschrich, Tina; Leich, Martin; Grimm, Stephan; Kobelke, Jens; Lorenz, Martin; Bartelt, Hartmut; Jäger, Matthias

2017-10-01

The use of short local tapers in large mode area fiber amplifiers is proposed for peak power scaling while maintaining good beam quality. To avoid modal distortions, the powder-sintering (REPUSIL) method was employed to obtain core materials with excellent refractive index homogeneity. First experiments with Yb3+-doped rod-type amplifiers delivered 2 ns pulses with peak powers of 540 kW and energies of 1.4 mJ for the untapered rod and 230 kW for the tapered rod (limited by facet damage). The beam quality improved from an M 2 value of approximately 10 to 3.5. The investigation of the taper structure indicates room for further improvement.

Enhanced Upconversion Luminescence in Yb3+/Tm3+-Codoped Fluoride Active Core/Active Shell/Inert Shell Nanoparticles through Directed Energy Migration

PubMed Central

Qiu, Hailong; Yang, Chunhui; Shao, Wei; Damasco, Jossana; Wang, Xianliang; Ågren, Hans; Prasad, Paras N.; Chen, Guanying

2014-01-01

The luminescence efficiency of lanthanide-doped upconversion nanoparticles is of particular importance for their embodiment in biophotonic and photonic applications. Here, we show that the upconversion luminescence of typically used NaYF4:Yb3+30%/Tm3+0.5% nanoparticles can be enhanced by ~240 times through a hierarchical active core/active shell/inert shell (NaYF4:Yb3+30%/Tm3+0.5%)/NaYbF4/NaYF4 design, which involves the use of directed energy migration in the second active shell layer. The resulting active core/active shell/inert shell nanoparticles are determined to be about 11 times brighter than that of well-investigated (NaYF4:Yb3+30%/Tm3+0.5%)/NaYF4 active core/inert shell nanoparticles when excited at ~980 nm. The strategy for enhanced upconversion in Yb3+/Tm3+-codoped NaYF4 nanoparticles through directed energy migration might have implications for other types of lanthanide-doped upconversion nanoparticles. PMID:28348285

Enhanced Upconversion Luminescence in Yb3+/Tm3+-Codoped Fluoride Active Core/Active Shell/Inert Shell Nanoparticles through Directed Energy Migration.

PubMed

Qiu, Hailong; Yang, Chunhui; Shao, Wei; Damasco, Jossana; Wang, Xianliang; Ågren, Hans; Prasad, Paras N; Chen, Guanying

2014-01-03

The luminescence efficiency of lanthanide-doped upconversion nanoparticles is of particular importance for their embodiment in biophotonic and photonic applications. Here, we show that the upconversion luminescence of typically used NaYF₄:Yb 3+ 30%/Tm 3+ 0.5% nanoparticles can be enhanced by ~240 times through a hierarchical active core/active shell/inert shell (NaYF₄:Yb 3+ 30%/Tm 3+ 0.5%)/NaYbF₄/NaYF₄ design, which involves the use of directed energy migration in the second active shell layer. The resulting active core/active shell/inert shell nanoparticles are determined to be about 11 times brighter than that of well-investigated (NaYF₄:Yb 3+ 30%/Tm 3+ 0.5%)/NaYF₄ active core/inert shell nanoparticles when excited at ~980 nm. The strategy for enhanced upconversion in Yb 3+ /Tm 3+ -codoped NaYF₄ nanoparticles through directed energy migration might have implications for other types of lanthanide-doped upconversion nanoparticles.

Tunable multicolor and enhanced red emission of monodisperse CaF2:Yb3+/Ho3+ microspheres via Mn2+ doping

NASA Astrophysics Data System (ADS)

Wang, Rui; Yuan, Maohui; Zhang, Chaofan; Wang, Hongyan; Xu, Xiaojun

2018-05-01

Transition metal ions (e.g. Mn2+) and lanthanide co-doped upconversion (UC) materials have attracted wide attention in recent years due to their promising application in multicolor display. Here, we report the hydrothermal synthesis and characterization of Mn2+ doped monodisperse CaF2:Yb3+/Ho3+ microspheres. The results of X-ray diffraction (XRD) revealed that Mn2+ doping does not change the cubic phase of CaF2 material but will lead to diffraction peaks shifting slightly towards higher angle due to the substitution of larger Ca2+ by the relatively smaller Mn2+. Under the excitation of 980 nm continuous wave (CW) laser, these microspheres exhibit green-yellow-red tuning colors and remarkable enhancement of both red to green ratio (R/G) and red to blue ratio (R/B) when increasing Mn2+ concentration from 0 to 30 mol%. The energy migration process between Ho3+ and Mn2+ was proposed and supported by time-decay and power dependence measurements of Ho3+ UC emission. These upconversion materials may have potential applications in optical devices, color display, nanoscale lasers and biomedical imaging.

Ce3+/Yb3+/Er3+ triply doped bismuth borosilicate glass: a potential fiber material for broadband near-infrared fiber amplifiers

PubMed Central

Chu, Yushi; Ren, Jing; Zhang, Jianzhong; Peng, Gangding; Yang, Jun; Wang, Pengfei; Yuan, Libo

2016-01-01

Erbium doped bismuth borosilicate (BBS) glasses, possessing the broadest 1.55 μm near infrared (NIR) emission band among oxide glasses, stand out as excellent fiber material for optical fiber amplifiers. In this work, we demonstrate that both broadened and enhanced NIR emission of Er3+ can be obtained by sensibly combining the effects such as mixed glass former effect, phonon-assisted energy transfer (PAET) and de-excitation effect induced by codopant. Specially, by codoping CeO2 in a controlled manner, it leads to not only much improved optical quality of the glasses, enhanced NIR emission, but also significantly suppressed energy transfer up-conversion (ETU) luminescence which is detrimental to the NIR emission. Cerium incorporated in the glasses exists overwhelmingly as the trivalent oxidation state Ce3+ and its effects on the luminescence properties of Er3+ are discussed. Judd-Ofelt analysis is used to evaluate gain amplification of the glasses. The result indicates that Ce3+/Yb3+/Er3+ triply doped BBS glasses are promising candidate for erbium doped fiber amplifiers. The strategy described here can be readily extended to other rare-earth ions (REs) to improve the performance of REs doped fiber lasers and amplifiers. PMID:27646191

Laser and spectroscopic properties of Sr[sub 5](PO[sub 4])[sub 3]F:Yb

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeLoach, L.D.; Payne, S.A.; Smith, L.K.

Sr[sub 5](PO[sub 4])[sub 3]F (S-FAP) has been investigated as a new Yb-doped laser crystal belonging to the apatite structural family. The spectroscopy of the Yb[sup 3+] ion and the laser properties of the medium have been investigated. The maximum absorption cross section of Yb in S-FAP is 8.6 [times] 10[sup [minus]20] cm[sup 2], and the maximum emission cross section is 7.3 [times] 10[sup [minus]20] cm[sup 2]. The measured emission lifetime of Yb[sup 3+] is 1.26 ms. An Yb:S-FAP laser has been demonstrated with a Ti:sapphire laser pump operating at 899 nm. The Yb:S-FAP laser was measured to have slope efficienciesmore » as high as 71%. The spectroscopy and laser studies are reported, as well as certain thermal, mechanical, and optical properties.« less

Spectral and multi-wavelength continuous-wave laser properties of Yb3+:BaLaGa3O7

NASA Astrophysics Data System (ADS)

Gao, Shufang; Xu, Shan

2018-05-01

Yb3+ doped BaLaGa3O7 crystal has been successfully grown by Czochralski method. The polarized absorption spectra, the fluorescence spectra and the fluorescence decay lifetime of Yb3+:BaLaGa3O7 crystal were measured at room temperature. The spectroscopic parameters of Yb3+:BaLaGa3O7 crystal are calculated. A continuous wave output power of 1.32W was obtained with four-wavelength emission corresponding to an optical-optical slope efficiency of 55%.

Optical temperature sensing of Er3+/Yb3+ doped LaGdO3 based on fluorescence intensity ratio and lifetime thermometry

NASA Astrophysics Data System (ADS)

Siaï, A.; Haro-González, P.; Horchani Naifer, K.; Férid, M.

2018-02-01

The investigation of the fluorescence intensity ratio and the lifetime thermometry techniques for two rare earth perovskites-type oxide (LaGdO3:Er3+ and LaGdO3:Er3+/Yb3+) has been carried out. We have demonstrated that the intensity ratio of thermally coupled levels of erbium (2H11/2 and 4S3/2) is temperature dependant in the range from 283 to 393 K. The sensitivity parameter was found to reach a maximum value of 31 × 10-4 K-1 and 34 × 10-4 K-1 at 393 K and the temperature resolution to be equivalent to 1.61 and 3.1 K, for Er3+ and Er3+/Yb3+ doped oxide, respectively. By studying the temperature dependence of the normalized lifetimes in the range from 293 to 348 K, we proved that the sensitivity of the green emission (4S3/2) is higher than the red one (4F9/2) for both samples, and that it increases from 144 × 10-4 K-1 for LaGdO3:Er3+ to 179 × 10-4 K-1 for LaGdO3:Er3+/Yb3+. The thermal coefficients were quite large in comparison to those calculated for different luminescent materials and reported in literature. The repeatability of measurements was tested by performing heating and cooling cycles for both methods and the results show that these optical techniques have a good repeatability performance. Hence, the LaGdO3: Er3+, Yb3+ oxide has a precise and a satisfying sensitivity associated to a good thermal and chemical stability, suggesting that it can be a potential candidate in temperature sensing.

Micro-joule pico-second range Yb3+-doped fibre laser for medical applications in acupuncture

NASA Astrophysics Data System (ADS)

Alvarez-Chavez, J. A.; Rivera-Manrique, S. I.; Jacques, S. L.

2011-08-01

The work described here is based on the optical design, simulation and on-going implementation of a pulsed (Q-switch) Yb3+-doped, 1-um diffraction-limited fibre laser with pico-second, 10 micro-Joule-range energy pulses for producing the right energy pulses which could be of benefit for patients who suffer chronic headache, photophobia, and even nausea which could is sometimes triggered by a series of factors. The specific therapeutic effect known as acupunctural analgesia is the main objective of this medium-term project. It is a simple design on which commercially available software was employed for laser cavity design. Monte Carlo technique for skin light-transport, thermal diffusion and the possible thermal de-naturalization optical study and prediction will also be included in the presentation. Full optical characterization will be included and a complete set of recent results on the laser-skin interaction and the so called moxi-bustion from the laser design will be extensively described.

Size-Tunable and Monodisperse Tm3+/Gd3+-Doped Hexagonal NaYbF4 Nanoparticles with Engineered Efficient Near Infrared-to-Near Infrared Upconversion for In Vivo Imaging

PubMed Central

2015-01-01

Hexagonal NaYbF4:Tm3+ upconversion nanoparticles hold promise for use in high contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and in vivo bioimaging. However, significant hurdles remain in their preparation and control of their morphology and size, as well as in enhancement of their upconversion efficiency. Here, we describe a systematic approach to produce highly controlled hexagonal NaYbF4:Tm3+ nanoparticles with superior upconversion. We found that doping appropriate concentrations of trivalent gadolinium (Gd3+) can convert NaYbF4:Tm3+ 0.5% nanoparticles with cubic phase and irregular shape into highly monodisperse NaYbF4:Tm3+ 0.5% nanoplates or nanospheres in a pure hexagonal-phase and of tunable size. The intensity and the lifetime of the upconverted NIR luminescence at 800 nm exhibit a direct dependence on the size distribution of the resulting nanoparticles, being ascribed to the varied surface-to-volume ratios determined by the different nanoparticle size. Epitaxial growth of a thin NaYF4 shell layer of ∼2 nm on the ∼22 nm core of hexagonal NaYbF4:Gd3+ 30%/Tm3+ 0.5% nanoparticles resulted in a dramatic 350 fold NIR upconversion efficiency enhancement, because of effective suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered saline. PMID:25027118

Minority-carrier lifetime in InP as a function of light bias

NASA Technical Reports Server (NTRS)

Yater, Jane A.; Weinberg, I.; Jenkins, Phillip P.; Landis, Geoffrey A.

1995-01-01

Minority-carrier lifetime in InP is studied as a function of doping level and laser intensity using time-resolved photoluminescence. A continuous wave diode laser illuminates bulk InP and acts as a light bias, injecting a steady-state concentration of carriers. A 200 ps laser pulse produces a small transient signal on top of the steady-state luminescence, allowing lifetime to be measured directly as a function of incident intensity. For p-InP, lifetime increases with light bias up to a maximum value. Bulk recombination centers are presumably filled to saturation, allowing minority carriers to live longer. The saturation bias scales with dopant concentration for a particular dopant species. As light bias is increased for n-InP, minority-carrier lifetime increases slightly but then decreases, suggesting radiative recombination as a dominant decay mechanism.

Structural and optical properties of rare earth-doped (Ba{sub 0.77}Ca{sub 0.23}){sub 1-x}(Sm, Nd, Pr, Yb){sub x}TiO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moraes, A. P. A.; Universidade Federal do Mato Grosso, 78060-900, Araguaia-MT; Filho, A. G. Souza

2011-06-15

The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba{sub 0.77}Ca{sub 0.23}TiO{sub 3} (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 deg. C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electronmore » microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO{sub 6} octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb{sup 3+} doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm{sup -1}, which is in agreement with lattice dynamics calculations.« less

Interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser

NASA Astrophysics Data System (ADS)

Wang, Da-Shuai; Wu, Ge; Gao, Bo; Tian, Xiao-Jian

2013-01-01

We numerically investigate the formation and interaction of a parabolic-shaped pulse pair in a passively mode-locked Yb-doped fiber laser. Based on a lumped model, the parabolic-shaped pulse pair is obtained by controlling the inter-cavity average dispersion and gain saturation energy, Moreover, pulse repulsive and attractive motion are also achieved with different pulse separations. Simulation results show that the phase shift plays an important role in pulse interaction, and the interaction is determined by the inter-cavity average dispersion and gain saturation energy, i.e., the strength of the interaction is proportional to the gain saturation energy, a stronger gain saturation energy will result in a higher interaction intensity. On the contrary, the increase of the inter-cavity dispersion will counterbalance some interaction force. The results also show that the interaction of a parabolic-shaped pulse pair has a larger interaction distance compared to conventional solitons.

Er 3+-Yb 3+ co-doped glass waveguide amplifiers using ion exchange and field-assisted annealing

NASA Astrophysics Data System (ADS)

Zhang, X. Z.; Liu, K.; Mu, S. K.; Tan, C. Z.; Zhang, D.; Pun, E. Y. B.; Zhang, D. M.

2006-12-01

Er 3+-Yb 3+ co-doped waveguide amplifiers fabricated using thermal two-step ion-exchange are demonstrated. K +-Na + ion-exchange process was first carried out in pure KNO 3 molten bath, and then field-assisted annealing (FAA) was used to make the buried waveguides. The effective buried depth is estimated to be ˜3.4 μm for the buried FAA waveguides. With the use of cut-back method, the fiber-to-guide coupling loss of ˜4.38 dB, the waveguide loss of ˜2.27 dB/cm, and Er 3+ absorption loss ˜5.7 dB were measured for a ˜1.24-cm-long waveguide. Peak relative gain of ˜7.0 dB is obtained for a ˜1.24-cm-long waveguide. The potential for the fabrication of compact optical amplifiers operating in the range of 1520-1580 nm is also demonstrated.

Temperature influence on diode pumped Yb:GGAG laser

NASA Astrophysics Data System (ADS)

Veselský, Karel; Boháček, Pavel; Šulc, Jan; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin

2017-05-01

We present temperature influence (in range from 78 up to 400,K) on spectroscopic properties and laser performance of new Yb-doped mixed garnet Gd3GaxAl5-xO12 (Yb:GGAG). The sample was 2.68 mm thick plane-parallel face-polished Yb:GGAG single-crystal plate which was AR coated for pump (930 nm) and generated (1030 nm) laser radiation wavelength. The composition of sample was Gd3.098Yb0:0897Ga2:41Al2.41O12 (3 at % Yb/Gd). The Yb:GGAG crystal was mounted in temperature controlled copper holder of the liquid nitrogen cryostat. The 138 mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (T > 90 % @ 930 nm, HR @ 1030 nm) placed inside cryostat, and a curved output coupler (r = 150 mm, R = 94.5 % @ 1030 nm) placed outside cryostat. For longitudinal pumping a fiber coupled laser diode was used. The diode was operating in the pulse regime (5 ms pulse length, 20 Hz repetition rate) at wavelength 928.5 nm. The absorption spectrum was measured for the temperatures from 78 to 400 K, and absorption lines narrowing was observed with temperature decrease. Zero-phonon line at 970 nm has width 1 nm (FWHM) at 100 K. The fluorescence intensity decay time was measured and it increased linearly with temperature from 864 μs @ 78 K to 881 μs @ 300 K. The temperature of active medium has strong influence mainly on laser threshold which was 5 times lower at 100 K than at 300 K, and on slope efficiency which was 3 times higher at 100 K than at 300 K.

Design, synthesis and luminescence properties of Ba2 YB2 O6 Cl- and Ba2 YB2 O6 F-based phosphors.

PubMed

Chen, Wanping; Yang, Xin; Liu, Yan; Dai, Xiaoyan

2015-05-01

Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range ~ 330-410 nm with a maximum around 363 nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range ~ 340-570 nm with a maximum around 383 nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7)  F2 emission (~610 nm) and the relative intensities of the (5) D0 -(7)  F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of doping on the forward current-transport mechanisms in a metal-insulator-semiconductor contact to INP:ZN grown by metal organic vapor phase epitaxy

NASA Astrophysics Data System (ADS)

Cova, P.; Singh, A.; Medina, A.; Masut, R. A.

1998-04-01

A detailed study of the effect of doping density on current transport was undertaken in Au metal-insulator-semiconductor (MIS) contacts fabricated on Zn-doped InP layers grown by metal organic vapor phase epitaxy. A recently developed method was used for the simultaneous analysis of the current-voltage ( I- V) and capacitance-voltage ( C- V) characteristics in an epitaxial MIS diode which brings out the contributions of different current-transport mechanisms to the total current. I- V and high-frequency C- V measurements were performed on two MIS diodes at different temperatures in the range 220-395 K. The barrier height at zero bias of Au/InP:Zn MIS diodes, φ0 (1.06 V±10%), was independent both of the Zn-doping density and of the surface preparation. The interface state density distribution Nss as well as the thickness of the oxide layer (2.2±15% nm) unintentionally grown before Au deposition were independent of the Zn-doping concentration in the range 10 16< NA<10 17 cm -3; not so the effective potential barrier χ of the insulator layer and the density of the mid-gap traps. χ was much lower for the highly-doped sample. Our results indicate that at high temperatures, independent of the Zn-doping concentration, the interfacial layer-thermionic (ITE) and interfacial layer-diffusion (ID) mechanisms compete with each other to control the current transport. At intermediate temperatures, however, ITE and ID will no longer be the only dominant mechanisms in the MIS diode fabricated on the highly-doped sample. In this case, the assumption of a generation-recombination current permits a better fit to the experimental data. Analysis of the data suggests that the generation-recombination current, observed only in the highly-doped sample, is associated with an increase in the Zn-doping density. From the forward I- V data for this diode we obtained the energy level (0.60 eV from the conduction band) for the most effective recombination centers.

Luminescence and photoinduced absorption in ytterbium-doped optical fibres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybaltovsky, A A; Aleshkina, S S; Likhachev, M E

2011-12-31

Photochemical reactions induced in the glass network of an ytterbium-doped fibre core by IR laser pumping and UV irradiation have been investigated by analysing absorption and luminescence spectra. We have performed comparative studies of the photoinduced absorption and luminescence spectra of fibre preforms differing in core glass composition: Al{sub 2}O{sub 3} : SiO{sub 2}, Al{sub 2}O{sub 3} : Yb{sub 2}O{sub 3} : SiO{sub 2}, and P{sub 2}O{sub 5} : Yb{sub 2}O{sub 3} : SiO{sub 2}. The UV absorption spectra of unirradiated preform core samples show strong bands peaking at 5.1 and 6.5 eV, whose excitation plays a key role inmore » photoinduced colour centre generation in the glass network. 'Direct' UV excitation of the 5.1- and 6.5-eV absorption bands at 244 and 193 nm leads to the reduction of some of the Yb{sup 3+} ions to Yb{sup 2+}. The photodarkening of ytterbium-doped fibres by IR pumping is shown to result from oxygen hole centre generation. A phenomenological model is proposed for the IR-pumping-induced photodarkening of ytterbium-doped fibres. The model predicts that colour centre generation in the core glass network and the associated absorption in the visible range result from a cooperative effect involving simultaneous excitation of a cluster composed of several closely spaced Yb{sup 3+} ions.« less

Doped YbRh2Si2: not only ferromagnetic correlations but ferromagnetic order.

PubMed

Lausberg, S; Hannaske, A; Steppke, A; Steinke, L; Gruner, T; Pedrero, L; Krellner, C; Klingner, C; Brando, M; Geibel, C; Steglich, F

2013-06-21

YbRh2Si2 is a prototypical system for studying unconventional antiferromagnetic quantum criticality. However, ferromagnetic correlations are present which can be enhanced via isoelectronic cobalt substitution for rhodium in Yb(Rh(1-x)Co(x))2Si2. So far, the magnetic order with increasing x was believed to remain antiferromagnetic. Here, we present the discovery of ferromagnetism for x = 0.27 below T(C) = 1.30  K in single crystalline samples. Unexpectedly, ordering occurs along the c axis, the hard crystalline electric field direction, where the g factor is an order of magnitude smaller than in the basal plane. Although the spontaneous magnetization is only 0.1 μB/Yb it corresponds to the full expected saturation moment along c taking into account partial Kondo screening.

Growth and characterization of Yb:Ho:YAG single crystal fiber

NASA Astrophysics Data System (ADS)

Yang, Yilun; Ye, Linhua; Bao, Renjie; Li, Shanming; Zhang, Peixiong; Xu, Min; Hang, Yin

2018-06-01

High quality Yb and Ho co-doped Y3Al5O12 single crystal fibers have been successfully grown by the laser heated pedestal growth method of up to 124 mm in length and 450 μm in diameter for the first time. The results of inductively coupled plasma-atomic emission spectrometry analysis, X-ray diffraction and Raman spectroscopy reveal that the lattice structure and doping concentrations of the SCF are the same as that of the bulk. Scanning electron microscopy microphotographs shows that the fibers only have minor diameter fluctuations within 0.5%.

Fluorine-18-labeled Gd3+/Yb3+/Er3+ co-doped NaYF4 nanophosphors for multimodality PET/MR/UCL imaging.

PubMed

Zhou, Jing; Yu, Mengxiao; Sun, Yun; Zhang, Xianzhong; Zhu, Xingjun; Wu, Zhanhong; Wu, Dongmei; Li, Fuyou

2011-02-01

Molecular imaging modalities provide a wealth of information that is highly complementary and rarely redundant. To combine the advantages of molecular imaging techniques, (18)F-labeled Gd(3+)/Yb(3+)/Er(3+) co-doped NaYF(4) nanophosphors (NPs) simultaneously possessing with radioactivity, magnetic, and upconversion luminescent properties have been fabricated for multimodality positron emission tomography (PET), magnetic resonance imaging (MRI), and laser scanning upconversion luminescence (UCL) imaging. Hydrophilic citrate-capped NaY(0.2)Gd(0.6)Yb(0.18)Er(0.02)F(4) nanophosphors (cit-NPs) were obtained from hydrophobic oleic acid (OA)-coated nanoparticles (OA-NPs) through a process of ligand exchange of OA with citrate, and were found to be monodisperse with an average size of 22 × 19 nm. The obtained hexagonal cit-NPs show intense UCL emission in the visible region and paramagnetic longitudinal relaxivity (r(1) = 0.405 s(-1)·(mM)(-1)). Through a facile inorganic reaction based on the strong binding between Y(3+) and F(-), (18)F-labeled NPs have been fabricated in high yield. The use of cit-NPs as a multimodal probe has been further explored for T(1)-weighted MR and PET imaging in vivo and UCL imaging of living cells and tissue slides. The results indicate that (18)F-labeled NaY(0.2)Gd(0.6)Yb(0.18)Er(0.02) is a potential candidate as a multimodal nanoprobe for ultra-sensitive molecular imaging from the cellular scale to whole-body evaluation. Copyright © 2010 Elsevier Ltd. All rights reserved.

High-efficiency cavity-dumped micro-chip Yb:YAG laser

NASA Astrophysics Data System (ADS)

Nishio, M.; Maruko, A.; Inoue, M.; Takama, M.; Matsubara, S.; Okunishi, H.; Kato, K.; Kyomoto, K.; Yoshida, T.; Shimabayashi, K.; Morioka, M.; Inayoshi, S.; Yamagata, S.; Kawato, S.

2014-09-01

High-efficiency cavity-dumped ytterbium-doped yttrium aluminum garnet (Yb:YAG) laser was developed. Although the high quantum efficiency of ytterbium-doped laser materials is appropriate for high-efficiency laser oscillation, the efficiency is decreased by their quasi-three/four laser natures. High gain operation by high intensity pumping is suitable for high efficiency oscillation on the quasi-three/four lasers without extremely low temperature cooling. In our group, highest efficiency oscillations for continuous wave, nanosecond to picosecond pulse lasers were achieved at room temperature by the high gain operation in which pump intensities were beyond 100 kW/cm2.

Effects of Doping on Thermal Conductivity of Pyrochlore Oxides for Advanced Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam

2006-01-01

Pyrochlore oxides of general composition, A2B2O7, where A is a 3(+) cation (La to Lu) and B is a 4(+) cation (Zr, Hf, Ti, etc.) have high melting point, relatively high coefficient of thermal expansion, and low thermal conductivity which make them suitable for applications as high-temperature thermal barrier coatings. The effect of doping at the A site on the thermal conductivity of a pyrochlore oxide La2Zr2O7, has been investigated. Oxide powders of various compositions La2Zr2O7, La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 were synthesized by the citric acid sol-gel method. These powders were hot pressed into discs and used for thermal conductivity measurements using a steady-state laser heat flux test technique. The rare earth oxide doped pyrochlores La(1.7)Gd(0.3)Zr2O7, La(1.7)Yb(0.3)Zr2O7 and La(1.7)Gd(0.15)Yb(0.15)Zr2O7 had lower thermal conductivity than the un-doped La2Zr2O7. The Gd2O3 and Yb2O3 co-doped composition showed the lowest thermal conductivity.

Single-crystalline cubic structured InP nanosprings

NASA Astrophysics Data System (ADS)

Shen, G. Z.; Bando, Y.; Zhi, C. Y.; Yuan, X. L.; Sekiguchi, T.; Golberg, D.

2006-06-01

Cubic structured nanosprings, InP nanosprings, have been synthesized via a simple thermochemical process using InP and ZnS as the source materials. Each InP nanospring is formed by rolling up a single InP nanobelt with the growth direction along the ⟨111⟩ orientation. The formation of these novel nanostructures is mainly attributed to the minimization of the electrostatic energy due to the polar charges on the ±(002) side surfaces of cubic InP. Cathodoluminescence properties were also studied, which reveal that the InP nanosprings have three emission bands centered at ˜736, ˜920, and ˜980nm.

Luminescent and lasing characteristics of heavily doped Yb{sup 3+}:KY(WO{sub 4}){sub 2} crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kisel', V E; Troshin, A E; Shcherbitskii, V G

The luminescence decay times are measured taking into account reabsorption for KY(WO{sub 4}){sub 2}:Yb(KYW:Yb) crystals with atomic concentrations of active ions from 0.2% to 30%. The radiative lifetime of Yb{sup 3+} ions was measured to be 233 {mu}s. The cw output power of 1.46 and 1.62 W was achieved with the slope efficiency 52% and 47% for Yb:KYW lasers with the atomic concentration of Yb{sup 3+} ions equal to 10% and 30%, respectively. Using a semiconductor mirror with a saturable absorber (SESAM) in the passive mode-locking regime, pulses of duration 194 and 180 fs were obtained at wavelengths of 1042more » and 1039 nm for crystals with Yb{sup 3+} concentrations equal to 10% and 30%, respectively, the average output power being 0.63 and 0.75 W. (lasers and amplifiers)« less

Near-infrared photoluminescence in La0.98AlO3: 0.02Ln3+(Ln = Nd/Yb) for sensitization of c-Si solar cells

NASA Astrophysics Data System (ADS)

Sawala, N. S.; Koparkar, K. A.; Bajaj, N. S.; Omanwar, S. K.

2016-05-01

The host matrix LaAlO3 was synthesized by conventional solid state reaction method in which the Nd3+ ions and Yb3+ ions successfully doped at 2mol% concentrations. The phase purity was confirmed by X ray powder diffraction (XRD) method. The photoluminescence (PL) properties were studied by spectrophotometer in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Nd3+ ion doped LaAlO3 converts a visible (VIS) green photon (587 nm) into near infrared (NIR) photon (1070 nm) while Yb3+ ion doped converts ultra violet (UV) photon (221 nm) into NIR photon (980 nm). The La0.98AlO3: 0.02Ln3+(Ln = Nd / Yb) can be potentiality used for betterment of photovoltaic (PV) technology. This result further indicates its potential application as a luminescence converter layer for enhancing solar cells performance.

Highly scalable, resonantly cladding-pumped, Er-doped fiber laser with record efficiency.

PubMed

Dubinskii, M; Zhang, J; Ter-Mikirtychev, V

2009-05-15

We report the performance of a resonantly cladding-pumped, Yb-free, Er-doped fiber laser. We believe this is the first reported resonantly cladding-pumped fiber-Bragg-grating-based, Er-doped, large-mode-area (LMA) fiber laser. The laser, pumped by fiber-coupled InGaAsP/InP laser diode modules at 1,532.5 nm, delivers approximately 48 W of cw output at 1,590 nm. It is believed to be the highest power ever reported from a Yb-free Er-doped LMA fiber. This fully integrated laser also has the optical-to-optical efficiency of approximately 57%, to the best of our knowledge, the highest efficiency reported for cladding-pumped unidirectionally emitting Er-doped laser.

Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji

2014-08-15

Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900more » K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.« less

Ytterbium-doped Y 2O 3 nanoparticle silica optical fibers for high power fiber lasers with suppressed photodarkening

NASA Astrophysics Data System (ADS)

Yoo, S.; Kalita, M. P.; Boyland, A. J.; Webb, A. S.; Standish, R. J.; Sahu, J. K.; Paul, M. C.; Das, S.; Bhadra, S. K.; Pal, M.

2010-09-01

We report efficient laser demonstration and spectroscopic characteristics of a Yb-doped Y 2O 3 (or Y 3Al 5O 12) nanoparticle silica fiber developed by conventional fiber fabrication technique. The spectroscopy study evidences modification in the environment of Yb ions by the Y 2O 3 nanoparticles. As a result, photodarkening induced loss is reduced by 20 times relative to Yb-doped aluminosilicate fibers. The fiber is suitable for power scaling with good laser slope efficiency of 79%.

980 nm all-fiber NPR mode-locking Yb-doped phosphate fiber oscillator and its amplifier

NASA Astrophysics Data System (ADS)

Li, Pingxue; Yao, Yifei; Chi, Junjie; Hu, Haowei; Yang, Chun; Zhao, Ziqiang; Zhang, Guangju

2014-12-01

We report on a 980 nm all-fiber passively mode-locking Yb-doped phosphate fiber oscillator with the nonlinear polarization rotation (NPR) technique and its amplifier. In order to obtaining the stable self-starting mode-locking oscillator at 980 nm, a bandpass filter with 30 nm transmission bandwidth around 980 nm is inserted into the cavity. The oscillator generates the average output power of 26.1 mW with the repetition rate of 20.38 MHz, corresponding to the single pulse energy of 1.28 nJ. The pulse width is 159.48 ps. The output spectrum of the pulses is centered at 977 nm with a full width half maximum (FWHM) of 10 nm and has the characteristic steep spectral edges of dissipative soliton. No undesired ASE and harmful oscillation around 1030 nm is observed. Moreover, through two stage all-fiber-integrated amplifier by using the 980 nm oscillator as seed source, an amplified output power of 205 mW at 980 nm and pulse duration of 178.10 ps is achieved.

Peptides for functionalization of InP semiconductors.

PubMed

Estephan, Elias; Saab, Marie-belle; Larroque, Christian; Martin, Marta; Olsson, Fredrik; Lourdudoss, Sebastian; Gergely, Csilla

2009-09-15

The challenge is to achieve high specificity in molecular sensing by proper functionalization of micro/nano-structured semiconductors by peptides that reveal specific recognition for these structures. Here we report on surface modification of the InP semiconductors by adhesion peptides produced by the phage display technique. An M13 bacteriophage library has been used to screen 10(10) different peptides against the InP(001) and the InP(111) surfaces to finally isolate specific peptides for each orientation of the InP. MALDI-TOF/TOF mass spectrometry has been employed to study real affinity of the peptide towards the InP surfaces. The peptides serve for controlled placement of biotin onto InP to bind then streptavidin. Our Atomic Force Microscopy study revealed a total surface coverage of molecules when the InP surface was functionalized by its specific biotinylated peptide (YAIKGPSHFRPS). Finally, fluorescence microscopy has been employed to demonstrate the preferential attachment of the peptide onto a micro-patterned InP surface. Use of substrate specific peptides could present an alternative solution for the problems encountered in the actually existing sensing methods and molecular self-assembly due to the unwanted unspecific interactions.

Three-dimensional modeling of CPA to the multimillijoule level in tapered Yb-doped fibers for coherent combining systems.

PubMed

Andrianov, Alexey; Anashkina, Elena; Kim, Arkady; Meyerov, Iosif; Lebedev, Sergey; Sergeev, Alexander; Mourou, Gerard

2014-11-17

We developed a three-dimensional numerical model of Large-Mode-Area chirped pulse fiber amplifiers which includes nonlinear beam propagation in nonuniform multimode waveguides as well as gain spectrum dynamics in quasi-three-level active ions. We used our model in tapered Yb-doped fiber amplifiers and showed that single-mode propagation is maintained along the taper even in the presence of strong Kerr nonlinearity and saturated gain, allowing extraction of up to 3 mJ of output energy in 1 ns pulse. Energy scaling and its limitation as well as the influence of fiber taper bending and core irregularities on the amplifier performance were studied. We also investigated numerically the capabilities for compression and coherent combining of up to 36 perturbed amplifying channels and showed more than 70% combining efficiency, even with up to 11% of high-order modes in individual channels.

Tunable and switchable dual-wavelength dissipative soliton generation in an all-normal-dispersion Yb-doped fiber laser with birefringence fiber filter.

PubMed

Zhang, Z X; Xu, Z W; Zhang, L

2012-11-19

We report the generation of tunable single- and dual-wavelength dissipative solitons in an all-normal-dispersion mode-locked Yb-doped fiber laser, to the best of our knowledge, for the first time. Besides single-wavelength mode-locking, dual-wavelength mode-locking was achieved using an in-line birefringence fiber filter with periodic multiple passbands, which not only allows multiple wavelengths to oscillate simultaneously but also performs spectrum modulation on highly chirped dissipative pulse. Furthermore, taking advantage of the tunability of the birefringence fiber filter, wavelength tuning for both single- and dual-wavelength dissipative soliton mode-locking was realized. The dual-wavelength operation is also switchable. The all-fiber dissipative laser with flexible outputs can meet diverse application needs.

Survey and research on up-conversion emission character and energy transition of Yb3+/Er3+/Tm3+ co-doped phosphate glass and glass ceramic

NASA Astrophysics Data System (ADS)

Yu, Yin; Song, Feng; Ming, Chengguo; Liu, Jiadong; Li, Wei; Liu, Yanling; Zhao, Hongyan

2012-11-01

By conventional high-temperature melting method, Yb3+/Er3+/Tm3+ co-doped phosphate glass was synthesized. After annealing the precursor glass, the phosphate glass ceramic (GC) was obtained. By measuring the X-ray diffraction (XRD) spectrum, it is proved that the LiYbP4O12 and Li6P6O18 nano-crystals have existed in the phosphate GC. The up-conversion (UC) emission intensity of the GC is obvious stronger compared to that of the glass. The reason is that the shorter distance between rare earth ions in the glass ceramic increases the energy transitions from the sensitized ions (Yb3+) to the luminous ions (Er3+ and Tm3+). By studying the dependence of UC emissions on the pump power, the 523 and 546 nm green emissions of Er3+ ions in the glass are two-photon processes. But in the glass ceramic, they are two/three-photon processes. The phenomenon implies that a three-photon process has participated in the population of the two green emissions. Using Dexter theory, we discuss the energy transitions of Er3+ and Tm3+. The results indicate the energy transition of Tm3+ to Er3+ is very strong in the GC, which changes the population mechanism of UC emissions of Er3+.

Size-tunable and monodisperse Tm³⁺/Gd³⁺-doped hexagonal NaYbF₄ nanoparticles with engineered efficient near infrared-to-near infrared upconversion for in vivo imaging.

PubMed

Damasco, Jossana A; Chen, Guanying; Shao, Wei; Ågren, Hans; Huang, Haoyuan; Song, Wentao; Lovell, Jonathan F; Prasad, Paras N

2014-08-27

Hexagonal NaYbF4:Tm(3+) upconversion nanoparticles hold promise for use in high contrast near-infrared-to-near-infrared (NIR-to-NIR) in vitro and in vivo bioimaging. However, significant hurdles remain in their preparation and control of their morphology and size, as well as in enhancement of their upconversion efficiency. Here, we describe a systematic approach to produce highly controlled hexagonal NaYbF4:Tm(3+) nanoparticles with superior upconversion. We found that doping appropriate concentrations of trivalent gadolinium (Gd(3+)) can convert NaYbF4:Tm(3+) 0.5% nanoparticles with cubic phase and irregular shape into highly monodisperse NaYbF4:Tm(3+) 0.5% nanoplates or nanospheres in a pure hexagonal-phase and of tunable size. The intensity and the lifetime of the upconverted NIR luminescence at 800 nm exhibit a direct dependence on the size distribution of the resulting nanoparticles, being ascribed to the varied surface-to-volume ratios determined by the different nanoparticle size. Epitaxial growth of a thin NaYF4 shell layer of ∼2 nm on the ∼22 nm core of hexagonal NaYbF4:Gd(3+) 30%/Tm(3+) 0.5% nanoparticles resulted in a dramatic 350 fold NIR upconversion efficiency enhancement, because of effective suppression of surface-related quenching mechanisms. In vivo NIR-to-NIR upconversion imaging was demonstrated using a dispersion of phospholipid-polyethylene glycol (DSPE-PEG)-coated core/shell nanoparticles in phosphate buffered saline.

Highly-efficient multi-watt Yb:CaLnAlO4 microchip lasers

NASA Astrophysics Data System (ADS)

Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Xu, Xiaodong; Xu, Jun; Yumashev, Konstantin; Griebner, Uwe; Petrov, Valentin; Aguiló, Magdalena; Díaz, Francesc; Major, Arkady

2017-02-01

Tetragonal rare-earth calcium aluminates, CaLnAlO4 where Ln = Gd or Y (CALGO and CALYO, respectively), are attractive laser crystal hosts due to their locally disordered structure and high thermal conductivity. In the present work, we report on highly-efficient power-scalable microchip lasers based on 8 at.% Yb:CALGO and 3 at.% Yb:CALYO crystals grown by the Czochralski method. Pumped by an InGaAs laser diode at 978 nm, the 6 mm-long Yb:CALGO microchip laser generated 7.79 W at 1057-1065 nm with a slope efficiency of η = 84% (with respect to the absorbed pump power) and an optical-to-optical efficiency of ηopt = 49%. The 3 mm-long Yb:CALYO microchip laser generated 5.06 W at 1048-1056 nm corresponding to η = 91% and ηopt = 32%. Both lasers produced linearly polarized output (σ- polarization) with an almost circular beam profile and beam quality factors M2 x,y <1.1. The output performance of the developed lasers was modeled yielding a loss coefficient as low as 0.004-0.007 cm-1. The results indicate that the Yb3+- doped calcium aluminates are very promising candidates for high-peak-power passively Q-switched microchip lasers.

Broadband near-infrared downconversion luminescence in Eu2+-Yb3+ codoped Ca9Y(PO4)7

NASA Astrophysics Data System (ADS)

Sun, Jiayue; Zhou, Wei; Sun, Yining; Zeng, Junhui

2013-06-01

An efficient broadband near-infrared (NIR) quantum cutting was demonstrated in Eu2+-Yb3+ codoped Ca9Y(PO4)7 phosphor. Upon excitation of Eu2+ ions to the 4f65d1 level with an ultraviolet photon at 322 nm, emissions of two NIR photons at 983 nm of Yb3+were achieved. The dependences of the visible and NIR emissions, the decay lifetime, the energy transfer efficiency (ETE), and the quantum efficiency (QE) on the Yb3+ doping content were investigated in detail. The results indicated that the maximum ETE and the corresponding downconversion QE can reach between 80% and 179%, respectively.

Studies on up/down-conversion emission of Yb3+ sensitized Er3+ doped MLa2(MoO4)4 (M = Ba, Sr and Ca) phosphors for thermometry and optical heating

NASA Astrophysics Data System (ADS)

Sinha, Shriya; Kumar, Kaushal

2018-01-01

The photoluminescence properties of Yb3+ sensitized Er3+ doped BaLa2(MoO4)4, SrLa2(MoO4)4 and CaLa2(MoO4)4 phosphors synthesized via hydrothermal method are investigated upon 980 nm and 380 nm light excitations. The phase, purity, and morphology of the samples are characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Field emission scanning electron microscope. Among these three phosphors, the strongest emission intensity is seen in BaLa2(MoO4)4: Er3+/Yb3+ through both the 980 nm and 380 nm light excitations and is explained by the lifetime measurement of 4S3/2 level of Er3+ ion. Temperature sensing measurements were performed by using the fluorescence intensity ratio (FIR) of green emission bands originated from the two thermally coupled 2H11/2 → 4I15/2 and 4S3//2 → 4I15/2 transitions of Er3+ and maximum temperature sensitivity of 1.05% K-1 at 305 K is found for BLa2(MoO4)4: Er3+/Yb3+ sample. Moreover, the laser induced heating is measured in the samples and the maximum temperature of the sample particles is calculated as 422 K at 76 W/cm2 in BaLa2(MoO4)4: Er3+/Yb3+, pointing out large amount of heat generation in such phosphors. The BaLa2(MoO4)4: Er3+/Yb3+ also exhibits higher photothermal conversion efficiency of 46.7%.

Remote Water Temperature Measurements Based on Brillouin Scattering with a Frequency Doubled Pulsed Yb:doped Fiber Amplifier

PubMed Central

Schorstein, Kai; Popescu, Alexandru; Göbel, Marco; Walther, Thomas

2008-01-01

Temperature profiles of the ocean are of interest for weather forecasts, climate studies and oceanography in general. Currently, mostly in situ techniques such as fixed buoys or bathythermographs deliver oceanic temperature profiles. A LIDAR method based on Brillouin scattering is an attractive alternative for remote sensing of such water temperature profiles. It makes it possible to deliver cost-effective on-line data covering an extended region of the ocean. The temperature measurement is based on spontaneous Brillouin scattering in water. In this contribution, we present the first water temperature measurements using a Yb:doped pulsed fiber amplifier. The fiber amplifier is a custom designed device which can be operated in a vibrational environment while emitting narrow bandwidth laser pulses. The device shows promising performance and demonstrates the feasibility of this approach. Furthermore, the current status of the receiver is briefly discussed; it is based on an excited state Faraday anomalous dispersion optical filter. PMID:27873842

Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

DOE PAGES

Hu, Yanyun; Chen, Ning; Clancy, J. P.; ...

2017-12-29

We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

Local structure investigation of Ga and Yb dopants in Co 4 Sb 12 skutterudites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Yanyun; Chen, Ning; Clancy, J. P.

We report our x-ray absorption spectroscopy studies at both Ga K-edge and Yb L 2-edge to elucidate the local structure of Ga and Yb dopants in Yb xGa yCo 4Sb 12. Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24g site replacing Sb, and the other is the 2a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2a on-center site. At low concentrations of Yb,more » Ga 24g and Ga 2a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Mater. 23, 3194 (2013)]. The Ga 24g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24g site for the highest Yb concentration (x = 0.4). In addition to the local crystal structure evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K-edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga 2a to Ga 24g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co 4Sb 12 skutterudites is due to the increased Ga 24g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.« less

The complexity of the CaF2:Yb system: evidence that CaF2:Yb2+ is not an impurity trapped exciton system

NASA Astrophysics Data System (ADS)

Mackeen, Cameron; Bridges, Frank; Kozina, Michael; Mehta, Apurva; Reid, M. F.; Wells, J.-P. R.; BarandiaráN, Zoila

Fluorite crystal structures doped with rare-earth elements exhibit an anomalous redshifted luminescence upon UV excitation, generally attributed to the relaxation of impurity trapped excitons (ITE). We find that the intensity of this luminescence decreases as the total concentration of Yb 2+ increases in unexposed samples, which is in conflict with the currently accepted ITE model. Further, using x-ray absorption spectroscopy and UV-vis studies of CaF2:Yb, we find a large (but reversible) Yb valence reduction upon x-ray exposure at 200 K - from mostly 3+ to 2+. This valence reduction is stable for long time periods at low T < 50 K, but reverts to the initial state upon warming to 300 K. After reverting to the initial valence state of 3+ the anomalous luminescence does not reappear; only after annealing at 900 K do we again observe the anomalous emission below 150 K. To explore the mechanism at work, we employ extended x-ray fine-structure absorption spectroscopy (EXAFS) to probe local structure and its role in the anomalous luminescence. The x-ray and emission studies show that CaF2:Yb is not described by the ITE model; the data appear more consistent with an intervalence charge transfer (IVCT) model. It is likely that many similar ITE systems have also been misidentified.

NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Er{sup 3+}/Yb{sup 3+}) microspheres: the synthesis and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Zhiyi; Wang, Zhiying; Fu, Linlin

The strong green upconversion (UC) emission were observed in various Er{sup 3+}, Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples synthesized via a hydrothermal route. The UC intensity depends on the dopant concentration, and the optimal UC emission was obtained in NaLa(MoO{sub 4}){sub 2}: 0.02Er{sup 3+}/0.10 Yb{sup 3+}. - Highlights: • The NaLa(MoO{sub 4}){sub 2} microspheres doped with Eu{sup 3+}, Sm{sup 3+} and Er{sup 3+}/Yb{sup 3+} were synthesized by a hydrothermal method. • The effects of the EDTA in the initial solution crystal phase and morphology were studied. • The down-conversion luminescence properties of NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+}more » = Eu{sup 3+}, Sm{sup 3+}) were investigated. • The UC luminescence properties and mechanism of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} was discussed. - Abstract: NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}) microspheres have been synthesized at 180 °C via a facile EDTA-mediated hydrothermal route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the samples. It was found that the amount of EDTA in the initial solution was responsible for crystal phase and shape determination. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity was also investigated in details. Furthermore, the up-conversion (UC) emissions have been observed in a series of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples. Concentration dependent studies revealed that the optimal composition was realized for a 2% Er{sup 3+} and 10% Yb{sup 3+}-doping concentration.« less

Encapsulation and Implantation Studies of InP.

DTIC Science & Technology

1982-07-01

concluded that PSG encapsulation best preserves the initial characteristics of encapsulated InP during furnace anneals. ( t PL measurements indicate that...gradients in these zones than does Fe. Under typical annealing conditions for InP ( T > 700 C, t = 15-30 min) it is observed using SIMS that implanted 9Be...conditions for InP ( T > 700*C, t - 15-30 min) it is observed using SIMS that implanted 9Be is a rapid diffusant in SI InP. High dose (1015 cm -2

Enhanced photovoltaic performance of dye-sensitized solar cells based on NaYF4:Yb(3+), Er(3+)-incorporated nanocrystalline TiO2 electrodes.

PubMed

Zhu, Guang; Wang, Hongyan; Zhang, Quanxin; Zhang, Li

2015-08-01

Near infrared to visible up-conversion of light by rare earth ion-doped phosphors (NaYF4:Yb(3+), Er(3+)) that convert multiple photons of lower energy to higher energy photons offer new possibilities for improved performance of photovoltaic devices. Here, up-conversion phosphor NaYF4:Yb(3+), Er(3+) doped nanocrystalline TiO2 films are designed and used as a electrode for dye-sensitized solar cells, and the photovoltaic performance of DSSCs based on composite electrodes are investigated. The results show the cell with NaYF4:Yb(3+), Er(3+) achieves a power conversion efficiency of 7.65% under one sun illumination (AM 1.5G, 100mWcm(-2)), which is an increase of 14% compared to the cell without NaYF4:Yb(3+), Er(3+) (6.71%). The performance improvement is attributed to the dual effects of enhanced light harvesting from extended light absorption range and increased light scattering, and lower electron transfer resistance. Copyright © 2015 Elsevier Inc. All rights reserved.

The dawn of computer-assisted robotic osteotomy with ytterbium-doped fiber laser.

PubMed

Sotsuka, Yohei; Nishimoto, Soh; Tsumano, Tomoko; Kawai, Kenichiro; Ishise, Hisako; Kakibuchi, Masao; Shimokita, Ryo; Yamauchi, Taisuke; Okihara, Shin-ichiro

2014-05-01

Currently, laser radiation is used routinely in medical applications. For infrared lasers, bone ablation and the healing process have been reported, but no laser systems are established and applied in clinical bone surgery. Furthermore, industrial laser applications utilize computer and robot assistance; medical laser radiations are still mostly conducted manually nowadays. The purpose of this study was to compare the histological appearance of bone ablation and healing response in rabbit radial bone osteotomy created by surgical saw and ytterbium-doped fiber laser controlled by a computer with use of nitrogen surface cooling spray. An Ytterbium (Yb)-doped fiber laser at a wavelength of 1,070 nm was guided by a computer-aided robotic system, with a spot size of 100 μm at a distance of approximately 80 mm from the surface. The output power of the laser was 60 W at the scanning speed of 20 mm/s scan using continuous wave system with nitrogen spray level 0.5 MPa (energy density, 3.8 × 10(4) W/cm(2)). Rabbits radial bone osteotomy was performed by an Yb-doped fiber laser and a surgical saw. Additionally, histological analyses of the osteotomy site were performed on day 0 and day 21. Yb-doped fiber laser osteotomy revealed a remarkable cutting efficiency. There were little signs of tissue damage to the muscle. Lased specimens have shown no delayed healing compared with the saw osteotomies. Computer-assisted robotic osteotomy with Yb-doped fiber laser was able to perform. In rabbit model, laser-induced osteotomy defects, compared to those by surgical saw, exhibited no delayed healing response.

Study of radiation induced effects in the luminescence of nanostructured Al2O3: Yb, Er crystals

NASA Astrophysics Data System (ADS)

Gonçalves, K. A.; Bitencourt, J. F. S.; Mittani, J. C. R.; Tatumi, S. H.

2010-11-01

Alumina crystals doped with Yb and Er were obtained by sol gel process and their morphologies and luminescence properties were discussed. Nanocrystals formations composed by Er2O3, Yb2O3 e Yb3Al5O12 were observed by TEM images, EDS, electron beam diffraction and XRD, at the surface of the alumina grains. The size of the nanocrystals were of about (36±2) nm and (182±8) nm for the samples calcinated at 1200oC and 1600oC, respectively. The sample codoped with 1mol% of Er and 2 mol% of Yb supplied the best results for Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). The growth intensity of dosimetric TL peak at 205oC was linear with gamma radiation doses and the same behavior was observed in OSL results.

Local structure investigation of Ga and Yb dopants in Co4Sb12 skutterudites

NASA Astrophysics Data System (ADS)

Hu, Yanyun; Chen, Ning; Clancy, J. P.; Salvador, James R.; Kim, Chang-Yong; Shi, Xiaoya; Li, Qiang; Kim, Young-June

2017-12-01

We report comprehensive x-ray absorption spectroscopy studies at both the Ga K edge and Yb L2 edge to elucidate the local structure of Ga and Yb dopants in YbxGayCo4Sb12 . Our extended x-ray absorption fine structure (EXAFS) data confirm that Ga atoms occupy two crystallographic sites: one is the 24 g site replacing Sb, and the other is the 2 a site in the off-center void position. We find that the occupancy ratio of these two sites varies significantly as a function of the filling fraction of additional Yb, which exclusively occupies the 2 a on-center site. At low concentrations of Yb, Ga24 g and Ga2 a dopants coexist and they form a charge-compensated compound defect proposed by Qiu et al. [Adv. Funct. Mater. 23, 3194 (2013), 10.1002/adfm.201202571]. The Ga24 g occupancy increases gradually with increasing Yb concentration, and almost all Ga occupies the 24 g site for the highest Yb concentration studied (x =0.4 ). In addition to the local structural evidence provided by our EXAFS data, we also present x-ray absorption near-edge structure (XANES) spectra, which show a small Ga K -edge energy shift as a function of Yb concentration consistent with the change from predominantly Ga2 a to Ga24 g states. Our result suggests that the increased solubility of Yb in Yb-Ga co-doped Co4Sb12 skutterudites is due to the increased Ga24 g electron acceptor, and thus provides an important strategy to optimize the carrier concentration in partially filled skutterudites.

Microwave sol–gel synthesis and upconversion photoluminescence properties of CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with incommensurately modulated structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Chang Sung; Aleksandrovsky, Aleksandr; Department of Photonics and Laser Technologies, Siberian Federal University, Krasnoyarsk 660079

2015-08-15

CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method. The crystal structure of CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} tungstates have been refined, and upconversion photoluminescence properties have been investigated. The synthesized particles, being formed after the heat-treatment at 900 °C for 16 h, showed a well crystallized morphology. Under the excitation at 980 nm, CaGd{sub 2}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} particles exhibited a strong 525-nm and a weak 550-nm emission bandsmore » in the green region and a very weak 655-nm emission band in the red region. The Raman spectrum of undoped CaGd{sub 2}(WO{sub 4}){sub 4} revealed about 12 narrow lines. The strongest band observed at 903 cm{sup −1} was assigned to the ν{sub 1} symmetric stretching vibration of WO{sub 4} tetrahedrons. The spectra of the samples doped with Er and Yb obtained under the 514.5 nm excitation were dominated by Er{sup 3+} luminescence preventing the recording of these samples Raman spectra. Concentration quenching of the erbium luminescence at {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2} transition is weak in the range of erbium doping level x{sub Er}=0.05–0.2, while, for transition {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2}, the signs of concentration quenching become pronounced at x{sub Er}=0.2. - Graphical abstract: CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er{sup 3+}/Yb{sup 3+} phosphors with the doping concentrations of Er{sup 3+} and Yb{sup 3+} (x=Er{sup 3+}+Yb{sup 3+}, Er{sup 3+}=0.05, 0.1, 0.2 and Yb{sup 3+}=0.2, 0.45) have been successfully synthesized by the microwave sol–gel method and the crystal structure refinement, and upconversion photoluminescence properties have been investigated. - Highlights: • CaGd{sub 2−x}(WO{sub 4}){sub 4}:Er

Energy transfer and optical gain properties of P{sub 2}O{sub 5}-ZnO-LiF: (Yb{sup 3+}, Er{sup 3+}) glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, C. Parthasaradhi, E-mail: cgparthasaradhi@gmail.com, E-mail: ktrkreddy@gmail.com; Naresh, V.; Reddy, K. T. Ramakrishna, E-mail: cgparthasaradhi@gmail.com, E-mail: ktrkreddy@gmail.com

2015-06-24

The present paper reports on the results pertaining to the emission properties of 0.5 mol% Er{sup 3+} and together (0.5 Yb{sup 3+} /0.5 Er{sup 3+}) doped PZL (P{sub 2}O{sub 5}-ZnO-LiF) glasses prepared by a melt quenching method. From the optical absorption data, absorption and stimulated emission cross-sections have been evaluated using McCumber’s theory and further cross-sectional gain has also been computed for Yb{sup 3+}/Er{sup 3+} doped glass. On exciting the single (Er{sup 3+}) and dual rare earth ions (Yb{sup 3+}/Er{sup 3+}) doped glass sample at λ{sub exci} = 379 nm, three emission bands in the visible region {sup 2}H{sub 11/2}→{sup 4}I{sub 15/2}more » (526 nm), {sup 4}S{sub 3/2}→{sup 4}I{sub 15/2} (549 nm) and {sup 4}F{sub 9/2}→{sup 4}I{sub 15/2} (664 nm) are observed and while at λ{sub exci} = 980 nm (Laser Diode) excitation a broad emission at 1530 nm attributed to {sup 4}H{sub 13/2}→{sup 4}I{sub 15/2} is observed in the NIR region. The enhancement in visible and NIR emission intensities with the addition of Yb{sup 3+} to Er{sup 3+} due to an energy transfer process from Yb{sup 3+} to Er{sup 3+} has been explained in terms of an energy level diagram.« less

Near-infrared photoluminescence in La{sub 0.98}AlO{sub 3}: {sub 0.02}Ln{sup 3+}(Ln = Nd/Yb) for sensitization of c-Si solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawala, N. S., E-mail: nssawala@gmail.com; Koparkar, K. A.; Omanwar, S. K.

2016-05-06

The host matrix LaAlO{sub 3} was synthesized by conventional solid state reaction method in which the Nd{sup 3+} ions and Yb{sup 3+} ions successfully doped at 2mol% concentrations. The phase purity was confirmed by X ray powder diffraction (XRD) method. The photoluminescence (PL) properties were studied by spectrophotometer in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Nd{sup 3+} ion doped LaAlO{sub 3} converts a visible (VIS) green photon (587 nm) into near infrared (NIR) photon (1070 nm) while Yb{sup 3+} ion doped converts ultra violet (UV) photon (221 nm) into NIR photon (980 nm). The La{sub 0.98}AlO{sub 3}: {sub 0.02}Ln{supmore » 3+}(Ln = Nd / Yb) can be potentiality used for betterment of photovoltaic (PV) technology. This result further indicates its potential application as a luminescence converter layer for enhancing solar cells performance.« less

Structural and optical properties of nano-sized K3Nd(PO4)2:Yb3+ orthophosphate.

PubMed

Mizer, D; Macalik, L; Tomaszewski, P E; Lisiecki, R; Godlewska, P; Matraszek, A; Szczygieł, I; Zawadzki, M; Hanuza, J

2009-09-01

Nanocrystals of tripotassium neodymium bis-phosphate(V) doped with ytterbium ions, K3Nd(PO4)2: Yb3+, were synthesized by Pechini method. The obtained grains, having an average size of about 40 nm, were characterised by X-ray, electron microscopic, electron absorption, luminescence and IR studies. Moreover, fluorescence decay studies were carried out at room temperature. The energy transfer from the Nd3+ to Yb3+ was described and discussed. The results were compared to those of the K3Nd(PO4)2 bulk crystal.

Low-temperature magnetoelectric effect in multiferroic h-Yb1-xHoxMnO3

NASA Astrophysics Data System (ADS)

Zhang, Jincang; Gang, Qiang; Fang, Yifei

In this work, we study the low-temperature ferroelectricity, magnetic property and ME effect in Yb1-xHoxMnO3. In YbMnO3, ferroelectric polarization (P) is closely related with the structure change derived from spin-reorientation process. The initial symmetric relationship of P between the upper and lower half of magnetic sublattice will be broken, which gives rise to the detectable polarization. Additionally, the asymmetry of the P - T curves revealed the pinning effect of the defects in the material. In Ho-doped samples 2D antiferromagnetic perturbation as well as the second AFM ordering have been observed. Substitution of Yb by Ho atoms shows great influences on electric properties and the lowdoping concentration tend to be more favorable for the enhancement of P. The maximum polarization has been promoted hugely in Yb0.8Ho0.2MnO3. We suggested the variation of P is closely related with the stronger exchange interaction in Mn-O-Ho as well as the establishment of new Ho layers with the increase of Ho.

Synthesis and photocatalytic activity of ytterbium-doped titania/diatomite composite photocatalysts

NASA Astrophysics Data System (ADS)

Tang, Wenjian; Qiu, Kehui; Zhang, Peicong; Yuan, Xiqiang

2016-01-01

Ytterbium-doped titanium dioxide (Yb-TiO2)/diatomite composite materials with different Yb concentrations were prepared by sol-gel method. The phase structure, morphology, and chemical composition of the as-prepared composites were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and ultraviolet-visible (UV-vis) diffuse reflection spectroscopy. The XRD and Raman spectroscopy analysis indicated that the TiO2 existed in the form of pure anatase in the composites. The SEM images exhibited the well deposition and dispersion of TiO2 nanoparticles with little agglomeration on the surfaces of diatoms. The UV-vis diffuse reflection spectra showed that the band gap of TiO2 could be narrowed by the introduction of Yb species, which was further affected by doping concentration of Yb. The photocatalytic activity of synthesized samples was investigated by the degradation of methylene blue (MB) under UV light irradiation. It was observed that the photocatalytic degradation followed a pseudo-first-order kinetics according to the Langmuir-Hinshelwood model. Compared to TiO2 and TiO2/diatomite, the Yb-TiO2/diatomite composites exhibited higher photocatalytic activity toward degradation of MB using UV light irradiation.

Spin re-orientation in heavy fermion system α - YbAl1 - x FexB4

NASA Astrophysics Data System (ADS)

Wu, Shan; Broholm, C.; Kuga, K.; Suzuki, Shintaro; Nakatsuji, S.; Mourigal, M.; Stone, M.; Tian, Wei; Qiu, Y.; Rodriguez-Rivera, Jose

Non centro-symmetric α - YbAlB4 has a heavy Fermi liquid ground state and shares many characteristics with centro-symmetric β - YbAlB4 . Both isomorphs display intermediate valence, associated with a fluctuation scale of T0 = 200 K and a Kondo lattice scale of T* = 8 K. Unlike β - YbAlB4 , α - YbAlB4 is at the boundary of a transition from a Fermi liquid metallic state to an antiferromagnetic (AFM) insulating state, driven by Fe substitution of Al. Magnetization and specific heat measurements reveal two different antiferromagnetic phases with TN = 9 K and TN = 2 K for Fe concentration above and below x =0.07. We report single crystal neutron scattering experiments on Fe doped YbAlB4 with x =0.035 and x =0.125. While the ordering wave vector is identical, k -> = (1 , 0 , 0) , the spin orientation switches from c to a with increasing Fe concentration. This suggests different anisotropic hybridization between 4f and conduction electrons that we confirmed by determining the crystal field levels. Supported by DOE, BES through DE-FG02-08ER46544.

White light generation via up-conversion and blue tone in Er3+/Tm3+/Yb3+-doped zinc-tellurite glasses

NASA Astrophysics Data System (ADS)

Rivera, V. A. G.; Ferri, F. A.; Nunes, L. A. O.; Marega, E.

2017-05-01

Yb3+, Er3+ and Tm3+ triply doped zinc-tellurite glass have been prepared containing up to 3.23 wt% of rare-earth ion oxides, were characterized by absorption spectroscopy, excitation, emission and up-conversion spectra. Transparent and homogeneous glasses have been produced, managing the red, green and blue emission bands, in order to generate white light considering the human eye perception. The energy transfer (resonant or non-resonant) between those rare-earth ions provides a color balancing mechanism that maintains the operating point in the white region, generating warm white light, cool white light and artificial daylight through the increase of the 976/980 nm diode laser excitation power from 4 to 470 mW. A light source at 4000 K is obtained under the excitation at 980 nm with 15 mW, providing a white light environment that is comfortable to the human eye vision. The spectroscopic study presented in this work describes the white light generation by the triply-doped zinc-tellurite glass, ranging from blue, green and red, by controlling the laser excitation power and wavelength at 976/980 nm. Such white tuning provokes healthy effects on human health throughout the day, especially the circadian system.

High slope efficiency and high refractive index change in direct-written Yb-doped waveguide lasers with depressed claddings.

PubMed

Palmer, Guido; Gross, Simon; Fuerbach, Alexander; Lancaster, David G; Withford, Michael J

2013-07-15

We report the first Yb:ZBLAN and Yb:IOG10 waveguide lasers fabricated by the fs-laser direct-writing technique. Pulses from a Titanium-Sapphire laser oscillator with 5.1 MHz repetition rate were utilized to generate negative refractive index modifications in both glasses. Multiple modifications were aligned in a depressed cladding geometry to create a waveguide. For Yb:ZBLAN we demonstrate high laser slope efficiency of 84% with a maximum output power of 170 mW. By using Yb:IOG10 a laser performance of 25% slope efficiency and 72 mW output power was achieved and we measured a remarkably high refractive index change exceeding Δn = 2.3 × 10(-2).

An electron trap related to phosphorus deficiency in high-purity InP grown by metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Yamamoto, Norio; Uwai, Kunihiko; Takahei, Kenichiro

1989-04-01

Deep levels in high-purity InP crystal grown by metalorganic chemical vapor deposition (MOCVD) have been measured by deep level transient spectroscopy. While no electron traps are observed in the samples grown at 600 °C with a [PH3]/[In(C2H5)3] of 170, three electron traps with activation energies of 0.80, 0.44, and 0.24 eV were observed in the samples grown at 500 °C with the same [PH3]/[In(C2H5)3]. The 0.44-eV trap, whose capture cross section is 1.5×10-18 cm2, observed at a low [PH3]/[In(C2H5)3] shows a decrease in concentration as [PH3]/[In(C2H5)3] is increased, and becomes less than 5×1012 cm-3 at a [PH3]/[In(C2H5)3] of more than 170. The comparison of annealing behavior of this trap in MOCVD InP and that in liquid-encapsulated Czochralski InP suggests that the 0.44-eV trap is related to a complex formed from residual impurities and native defects related to a phosphorus deficiency such as phosphorus vacancies or indium interstitials. This trap is found to show configurational bistability similar to that observed for the trap in an Fe-doped InP, MFe center.

Space radiation effects in InP solar cells

NASA Astrophysics Data System (ADS)

Walters, R. J.; Messenger, S. R.; Summers, G. P.; Burke, E. A.; Keavney, C. J.

1991-12-01

InP solar cells and mesa diodes grown by metalorganic chemical vapor deposition (MOCVD) were irradiated with electrons and protons at room temperature. The radiation-induced defects (RIDs) were characterized by deep level transient spectroscopy (DLTS), and the degradation of the solar cell performance was determined through I-V measurements. The nonionizing energy loss (NIEL) of electrons and protons in InP was calculated as a function of energy from 1 to 200 MeV and compared to the measured defect introduction rates. A linear dependence was evident. InP solar cells showed significantly more radiation resistance than c-Si or GaAs/Ge cells under 1 MeV electron irradiation. Using the calculated InP damage rates and measured damage factors, the performance of InP solar cells as a function of orbital altitude and time in orbit was predicted and compared with the performance of c-Si solar cells in the same environment. In all cases, the InP cells showed highly superior radiation resistance.

Broadband down-conversion based near infrared quantum cutting in Eu{sup 2+}–Yb{sup 3+} co-doped SrAl{sub 2}O{sub 4} for crystalline silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tai, Yuping, E-mail: yupingtai@126.com; Zheng, Guojun, E-mail: zhengguojun88@126.com; Wang, Hui, E-mail: huiwang@nwu.edu.cn

2015-03-15

Near infrared (NIR) quantum cutting involving the down conversion of an absorbed visible photon to emission of two NIR photons was achieved in SrAl{sub 2}O{sub 4}:0.01Eu{sup 2+}, xYb{sup 3+} (x=0, 1, 2, 5, 10, 20, 30 mol%) samples. The photoluminescence properties of samples in visible and NIR regions were measured to verify the energy transfer (ET) from Eu{sup 2+} to Yb{sup 3+}. The results demonstrated that Eu{sup 2+} was an efficient sensitizer for Yb{sup 3+} in the SrAl{sub 2}O{sub 4} host lattice. According to Gaussian fitting analysis and temperature-dependent luminescence experiments, the conclusion was drawn that the cooperative energy transfermore » (CET) process dominated the ET process and the influence of charge transfer state (CTS) of Yb{sup 3+} could be negligible. As a result, the high energy transfer efficiency (ETE) and quantum yield (QY) have been acquired, the maximum value approached 73.68% and 147.36%, respectively. Therefore, this down-conversion material has potential application in crystalline silicon solar cells to improve conversion efficiency. - Graphical abstract: Near infrared quantum cutting was achieved in Eu{sup 2+}–Yb{sup 3+} co-doped SrAl{sub 2}O{sub 4} samples. The cooperative energy transfer process dominated energy transfer process and high energy transfer efficiency was acquired. - Highlights: • The absorption spectrum of Eu{sup 2+} ion is strong in intensity and broad in bandwidth. • The spectra of Eu{sup 2+} in SrAl{sub 2}O{sub 4} lies in the strongest region of solar spectrum. • The cooperative energy transfer (CET) dominated the energy transfer process. • The domination of CET is confirmed by experimental analysis. • SrAl{sub 2}O{sub 4}:Eu{sup 2+},Yb{sup 3+} show high energy transfer efficiency and long lifetime.« less

InP materials/cell fabrication

NASA Technical Reports Server (NTRS)

Coutts, T. J.

1987-01-01

The main points of discussion, conclusions and recommendations of a workshop on InP materials and cell fabrication are given. The importance of assessing the quality of p-Inp crystals supplied by different vendors, back contacts to solar cells, junction formation, energy conversion efficiency, testing for radiation resistance, and future develpments were among the topics discussed.

Energy-transfer processes in Yb:Tm-doped KY3F10, LiYF4, and BaY2F8 single crystals for laser operation at 1.5 and 2.3 μm

NASA Astrophysics Data System (ADS)

Braud, A.; Girard, S.; Doualan, J. L.; Thuau, M.; Moncorgé, R.; Tkachuk, A. M.

2000-02-01

Energy-transfer processes have been quantitatively studied in various Tm:Yb-doped fluoride crystals. A comparison between the three host crystals which have been examined (KY3F10, LiYF4, and BaY2F8) shows clearly that the efficiency of the Yb-->Tm energy transfers is larger in KY3F10 than in LiYF4 or BaY2F8. The dependence of the energy-transfer parameters upon the codopant concentrations has been experimentally measured and compared with the results calculated on the basis of migration-assisted energy-transfer models. Using these energy-transfer parameters and a rate equation model, we have performed a theoretical calculation of the laser thresholds for the 3H4-->3F4 and 3H4-->3H5 laser transitions of the Tm ion around 1.5 and 2.3 μm, respectively. Laser experiments performed at 1.5 μm in Yb:Tm:LiYF4 then led to laser threshold values in good agreement with those derived theoretically. Based on these results, optimized values for the Yb and Tm dopant concentrations for typical values of laser cavity and pump modes were finally derived to minimize the threshold pump powers for the laser transitions around 1.5 and 2.3 μm.

Narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using multimode interference filter.

PubMed

Chakravarty, Usha; Mukhopadhyay, P K; Kuruvilla, A; Upadhyaya, B N; Bindra, K S

2017-05-01

A narrow-linewidth broadly tunable Yb-doped Q-switched fiber laser using an acousto-optic modulator and multimode interference filter (MMIF) in the linear bulk cavity resonator and an all-fiber ring cavity resonator has been demonstrated. Insertion of an MMIF in the linear cavity resonator using bulk components decreased the spectral bandwidth of the Q-switched signal by two orders of magnitude from 11 to less than 0.1 nm. Spectral tunability of more than 16 nm in the range from 1057 to 1073 nm has also been achieved by the combination of MMIF and a standard polarization controller (SPC). A decrease in the pulse duration with a decrease in the spectral bandwidth of the output signal has also been recorded. The pulse duration of the Q-switched signal was reduced from ∼305 to ∼240  ns by the introduction of the MMIF in the resonator at the same value of the input pump power. In the case of the all-fiber Q-switched ring cavity resonator, the spectral bandwidth of the Q-switched signal was reduced by two orders of magnitude from ∼17 to less than 0.1 nm due to the introduction of the MMIF in the resonator. The spectral tunability of more than 12 nm in the range from 1038 to 1050 nm was achieved by an MMIF and an SPC.

Diode-pumped Yb:Sr{sub 5}(PO{sub 4}){sub 3}F laser performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C.D.; Payne, S.A.; Smith, L.K.

The performance of the first diode-pumped Yb{sup 3+}-doped Sr{sub 5}(PO{sub 4}){sub 3}F (Yb:S-FAP) laser is discussed. We found the pumping dynamics and extraction cross-sections of Yb:S-FAP crystals to be similar to those previously inferred by purely spectroscopic techniques. The saturation fluence for pumping was measured to be 2.2 J/cm{sup 2} using three different methods based on either the spatial, temporal, or energy transmission properties of a Yb:S-FAP rod. The small signal gain implies an emission cross section of 6.0 x 10{sup -20} cm{sup 2} that falls within error bars of the previously reported value of 7.3 x 10{sup -20} cm{supmore » 2}, obtained from spectroscopic techniques. Up to 1.7 J/cm{sup 3} of stored energy density was achieved in a 6 x 6 x 44 mm Yb:S-FAP amplifier rod. An InGaAs diode array has been fabricated that has suitable specifications for pumping a 3 x 3 x 30 mm Yb:S-FAP rod. In a free running configuration diode-pumped slope efficiencies up to 43% were observed with output energies up to {approximately}0.5 J per 1 ms pulse. When the rod was mounted in a copper block for cooling, 13 W of average power was produced with power supply limited operation at 70 Hz and 500 {mu}s pulses.« less

Large size crystalline vs. co-sintered ceramic Yb(3+):YAG disk performance in diode pumped amplifiers.

PubMed

Albach, Daniel; Chanteloup, Jean-Christophe

2015-01-12

A comprehensive experimental benchmarking of Yb(3+):YAG crystalline and co-sintered ceramic disks of similar thickness and doping level is presented in the context of high average power laser amplifier operation. Comparison is performed considering gain, depolarization and wave front deformation quantitative measurements and analysis.

Electronic structure of ferromagnetic heavy fermion, YbPdSi, YbPdGe, and YbPtGe studied by photoelectron spectroscopy, x-ray emission spectroscopy, and DFT + DMFT calculations

DOE PAGES

Yamaoka, Hitoshi; Thunstrom, Patrik; Tsujii, Naohito; ...

2017-11-02

Here, the electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d–4f resonance, resonant x-ray emission spectroscopy at the Yb L 3 absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with largemore » $${\\rm Yb}^{3+}$$ and small $${\\rm Yb}^{2+}$$ components. The magnitude of the Yb valence is evaluated to be YbPtGe $<$ YbPdGe $$\\lesssim $$ YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.« less

Electronic structure of ferromagnetic heavy fermion, YbPdSi, YbPdGe, and YbPtGe studied by photoelectron spectroscopy, x-ray emission spectroscopy, and DFT + DMFT calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamaoka, Hitoshi; Thunstrom, Patrik; Tsujii, Naohito

Here, the electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d–4f resonance, resonant x-ray emission spectroscopy at the Yb L 3 absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with largemore » $${\\rm Yb}^{3+}$$ and small $${\\rm Yb}^{2+}$$ components. The magnitude of the Yb valence is evaluated to be YbPtGe $<$ YbPdGe $$\\lesssim $$ YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.« less

High-energy and high-peak-power nanosecond pulse generation with beam quality control in 200-µm core highly multimode Yb-doped fiberamplifiers

NASA Astrophysics Data System (ADS)

Cheng, Ming-Yuan; Chang, Yu-Chung; Galvanauskas, Almantas; Mamidipudi, Pri; Changkakoti, Rupak; Gatchell, Peter

2005-02-01

We explored high-energy and high-peak-power pulse generation in large-core multimode fiber amplifiers, achieving what is to our knowledge the highest reported energies, up to 82 mJ for 500-ns pulses, 27 mJ for 50-ns pulses, and 2.4-MW peak power for 4-ns pulses at 1064 nm, using 200-µm-diameter and 0.062-N.A. core Yb-doped double-clad fiber amplifiers. The highly multimode nature of the fiber core was mitigated by use of a coiling-induced mode-filtering effect to yield a significant improvement in output-beam quality from M^2 = 25 from an uncoiled fiber to M^2 = 6.5 from a properly coiled fiber, with the corresponding reduction in number of propagating transverse modes from >or=200 to <or=20.

[The heating effect of the Er3+/Yb3+ doped Y2O3 nanometer powder by 980 nm laser diode pumping].

PubMed

Zheng, Long-Jiang; Gao, Xiao-Yang; Liu, Hai-Long; Li, Bing; Xu, Chen-Xi

2013-01-01

The Er3+ and Yb3+ doped Y2O3 Nano powder was prepared by sol-gel method. Based on 2H11/2 --> 4I15/2 and 4S3/2 --> 4I15/2 green conversion luminescence intensity rate of Er3+, the sample surface temperature changes caused by the increase in 980 nm diode laser pump power were studied. The results show that with pump power increasing, the sample surface temperature substantially rises. And the surface temperature reached to 820 K when the pump power was 1 000 mW. The phenomenon plays an important role in the analysis of upconversion process, especially with saturation power. And this feature has a potential application prospect in the biomedicine, soft tissue hole burning as well as the field of temperature sensing materials.

Rich stochastic dynamics of co-doped Er:Yb fluorescence upconversion nanoparticles in the presence of thermal, non-conservative, harmonic and optical forces

NASA Astrophysics Data System (ADS)

Nome, Rene A.; Sorbello, Cecilia; Jobbágy, Matías; Barja, Beatriz C.; Sanches, Vitor; Cruz, Joyce S.; Aguiar, Vinicius F.

2017-03-01

The stochastic dynamics of individual co-doped Er:Yb upconversion nanoparticles (UCNP) were investigated from experiments and simulations. The UCNP were characterized by high-resolution scanning electron microscopy, dynamic light scattering, and zeta potential measurements. Single UCNP measurements were performed by fluorescence upconversion micro-spectroscopy and optical trapping. The mean-square displacement (MSD) from single UCNP exhibited a time-dependent diffusion coefficient which was compared with Brownian dynamics simulations of a viscoelastic model of harmonically bound spheres. Experimental time-dependent two-dimensional trajectories of individual UCNP revealed correlated two-dimensional nanoparticle motion. The measurements were compared with stochastic trajectories calculated in the presence of a non-conservative rotational force field. Overall, the complex interplay of UCNP adhesion, thermal fluctuations and optical forces led to a rich stochastic behavior of these nanoparticles.

Violet-green excitation for NIR luminescence of Yb3+ ions in Bi2O3-B2O3-SiO2-Ga2O3 glasses.

PubMed

Li, Weiwei; Cheng, Jimeng; Zhao, Guoying; Chen, Wei; Hu, Lili; Guzik, Malgorzata; Boulon, Georges

2014-04-21

60Bi(2)O(3)-20B(2)O(3)-10SiO(2)-10Ga(2)O(3) glasses doped with 1-9 mol% Yb(2)O(3) were prepared and investigated mainly on their violet-green excitation for the typical NIR emission of Yb(3+), generally excited in the NIR. Two violet excitation bands at 365 nm and 405 nm are related to Yb(2+) and Bi(3+). 465 nm excitation band and 480 nm absorption band in the blue-green are assigned to Bi(0) metal nanoparticles/grains. Yb-content-dependence of the excitation and absorption means that Bi(0) is the reduced product of Bi(3+), but greatly competed by the redox reaction of Yb(2+) ↔ Yb(3+). It is proved that the violet-green excitations result in the NIR emission of Yb(3+). On the energy transfer, the virtual level of Yb(3+)-Yb(3+) as well as Bi(0) dimers probably plays an important role. An effective and controllable way is suggested to achieve nano-optical applications by Bi(0) metal nanoparticles/grains and Yb(3+).

Nd3+, Yb3+ and Ho3+ Codoped Oxyfluoride Glass Ceramics with High Efficient Green Upconversion Luminescence

NASA Astrophysics Data System (ADS)

Zhang, Jun-Jie; Kawamoto, Yoji; Dai, Shi-Xun; Zhang, Li-Yan; Hu, Li-Li

2004-06-01

New oxyfluoride glasses and glass ceramic codoped with Nd3+, Yb3+ and Ho3+ were prepared. The x-ray diffraction analysis revealed that the heat treatments of the oxyfluoride glasses could cause the precipitation of (Nd3+, Yb3+, Ho3+)-doped fluorite-type crystals. Very strong green up-conversion luminescence due to the Ho3+: (5F4, 5S2)rightarrow5I8 transition under 800-nm excitation was observed in these transparent glass ceramics. The intensity of the green up-conversion luminescence in a 1-mol% YbF3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho3+ up-conversion luminescence in the oxyfluoride glass ceramics is discussed.

Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

NASA Astrophysics Data System (ADS)

Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

2016-05-01

Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this

Study of Stark Effect in n-doped 1.55 μm InN0.92yP1-1.92yBiy/InP MQWs

NASA Astrophysics Data System (ADS)

Bilel, C.; Chakir, K.; Rebey, A.; Alrowaili, Z. A.

2018-05-01

The effect of an applied electric field on electronic band structure and optical absorption properties of n-doped InN0.92y P1-1.92y Bi y /InP multiple quantum wells (MQWs) was theoretically studied using a self-consistent calculation combined with the 16-band anti-crossing model. The incorporation of N and Bi atoms into an InP host matrix leads to rapid reduction of the band gap energy covering a large infrared range. The optimization of the well parameters, such as the well/barrier widths, N/Bi compositions and doping density, allowed us to obtain InN0.92y P1-1.92y Bi y /InP MQWs operating at the wavelength 1.55 μm. Application of the electric field causes a red-shift of the fundamental transition energy T 1 accompanied by a significant change in the spatial distribution of confined electron density. The Stark effect on the absorption coefficient of n-doped InN0.92y P1-1.92y Bi y /InP MQWs was investigated. The Bi composition of these MQWs was adjusted for each electric field value in order to maintain the wavelength emission at 1.55 μm.

Synthesis and properties of ultra-long InP nanowires on glass.

PubMed

Dhaka, Veer; Pale, Ville; Khayrudinov, Vladislav; Kakko, Joona-Pekko; Haggren, Tuomas; Jiang, Hua; Kauppinen, Esko; Lipsanen, Harri

2016-12-16

We report on the synthesis of Au-catalyzed InP nanowires (NWs) on low-cost glass substrates. Ultra-dense and ultra-long (up to ∼250 μm) InP NWs, with an exceptionally high growth rate of ∼25 μm min -1 , were grown directly on glass using metal organic vapor phase epitaxy (MOVPE). Structural properties of InP NWs grown on glass were similar to the ones grown typically on Si substrates showing many structural twin faults but the NWs on glass always exhibited a stronger photoluminescence (PL) intensity at room temperature. The PL measurements of NWs grown on glass reveal two additional prominent impurity related emission peaks at low temperature (10 K). In particular, the strongest unusual emission peak with an activation energy of 23.8 ± 2 meV was observed at 928 nm. Different possibilities including the role of native defects (phosphorus and/or indium vacancies) are discussed but most likely the origin of this PL peak is related to the impurity incorporation from the glass substrate. Furthermore, despite the presence of suspected impurities, the NWs on glass show outstanding light absorption in a wide spectral range (60%-95% for λ = 300-1600 nm). The optical properties and the NW growth mechanism on glass is discussed qualitatively. We attribute the exceptionally high growth rate mostly to the atmospheric pressure growth conditions of our MOVPE reactor and stronger PL intensity on glass due to the impurity doping. Overall, the III-V NWs grown on glass are similar to the ones grown on semiconductor substrates but offer additional advantages such as low-cost and light transparency.

Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

PubMed

Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

2016-04-01

For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display.

Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bobkov, K K; Rybaltovsky, A A; Vel'miskin, V V

2014-12-31

We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicatemore » glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)« less

Iron incorporation in InP layers using a ferrocene source in atmospheric pressure MOVPE

NASA Astrophysics Data System (ADS)

Robein, D.; Kazmierski, C.; Pougnet, A. M.; Rose, B.

1991-02-01

Iron incorporation into InP has been studied using an AP MOVPE method. A very good control of the iron doping has been obtained with a ferrocene diffusion cell source. Semi-insulating material with a resistivity as a high as 5 × 10 8 Ω cm has been measured on n-SI-n diodes with iron-doped 1 mum thick layers. A compensation activity of iron near 100% has been found. An iron incorporation activition energy of 2.5 eV has been determined below the solubility limit. The iron concentration was found to be proportional to the gas-phase ferrocene concentration and to follow an inverse square-root law under increasing phosphine flow. In order to explain the observed phenomena, an incorporation mechanism model is developed assuming a two-phosphorus vacancy— substitutional iron complex as the incorporated species.

Analysis of intrinsic optical bistability in Tm-doped laser-related crystals

NASA Astrophysics Data System (ADS)

Noginov, M. A.; Vondrova, M.; Casimir, D.

2003-11-01

We predict and theoretically study intrinsic optical bistability (IOB) mediated by nonlinear energy transfer processes in rare-earth-doped laser-related crystals. In particular, we investigate Tm-Ho and Tm-Yb systems, in which avalanche pumping is overimposed by energy transfer up-conversion. We predict that IOB can be experimentally observed in (Tm,Yb):BaY2F8 crystals in a wide range of experimentally achievable parameters.

DOR/Tp53inp2 and Tp53inp1 constitute a metazoan gene family encoding dual regulators of autophagy and transcription.

PubMed

Sancho, Ana; Duran, Jordi; García-España, Antonio; Mauvezin, Caroline; Alemu, Endalkachew A; Lamark, Trond; Macias, Maria J; DeSalle, Rob; Royo, Miriam; Sala, David; Chicote, Javier U; Palacín, Manuel; Johansen, Terje; Zorzano, Antonio

2012-01-01

Human DOR/TP53INP2 displays a unique bifunctional role as a modulator of autophagy and gene transcription. However, the domains or regions of DOR that participate in those functions have not been identified. Here we have performed structure/function analyses of DOR guided by identification of conserved regions in the DOR gene family by phylogenetic reconstructions. We show that DOR is present in metazoan species. Invertebrates harbor only one gene, DOR/Tp53inp2, and in the common ancestor of vertebrates Tp53inp1 may have arisen by gene duplication. In keeping with these data, we show that human TP53INP1 regulates autophagy and that different DOR/TP53INP2 and TP53INP1 proteins display transcriptional activity. The use of molecular evolutionary information has been instrumental to determine the regions that participate in DOR functions. DOR and TP53INP1 proteins share two highly conserved regions (region 1, aa residues 28-42; region 2, 66-112 in human DOR). Mutation of conserved hydrophobic residues in region 1 of DOR (that are part of a nuclear export signal, NES) reduces transcriptional activity, and blocks nuclear exit and autophagic activity under autophagy-activated conditions. We also identify a functional and conserved LC3-interacting motif (LIR) in region 1 of DOR and TP53INP1 proteins. Mutation of conserved acidic residues in region 2 of DOR reduces transcriptional activity, impairs nuclear exit in response to autophagy activation, and disrupts autophagy. Taken together, our data reveal DOR and TP53INP1 as dual regulators of transcription and autophagy, and identify two conserved regions in the DOR family that concentrate multiple functions crucial for autophagy and transcription.

DOR/Tp53inp2 and Tp53inp1 Constitute a Metazoan Gene Family Encoding Dual Regulators of Autophagy and Transcription

PubMed Central

Sancho, Ana; Duran, Jordi; García-España, Antonio; Mauvezin, Caroline; Alemu, Endalkachew A.; Lamark, Trond; Macias, Maria J.; DeSalle, Rob; Royo, Miriam; Sala, David; Chicote, Javier U.; Palacín, Manuel; Johansen, Terje; Zorzano, Antonio

2012-01-01

Human DOR/TP53INP2 displays a unique bifunctional role as a modulator of autophagy and gene transcription. However, the domains or regions of DOR that participate in those functions have not been identified. Here we have performed structure/function analyses of DOR guided by identification of conserved regions in the DOR gene family by phylogenetic reconstructions. We show that DOR is present in metazoan species. Invertebrates harbor only one gene, DOR/Tp53inp2, and in the common ancestor of vertebrates Tp53inp1 may have arisen by gene duplication. In keeping with these data, we show that human TP53INP1 regulates autophagy and that different DOR/TP53INP2 and TP53INP1 proteins display transcriptional activity. The use of molecular evolutionary information has been instrumental to determine the regions that participate in DOR functions. DOR and TP53INP1 proteins share two highly conserved regions (region 1, aa residues 28–42; region 2, 66–112 in human DOR). Mutation of conserved hydrophobic residues in region 1 of DOR (that are part of a nuclear export signal, NES) reduces transcriptional activity, and blocks nuclear exit and autophagic activity under autophagy-activated conditions. We also identify a functional and conserved LC3-interacting motif (LIR) in region 1 of DOR and TP53INP1 proteins. Mutation of conserved acidic residues in region 2 of DOR reduces transcriptional activity, impairs nuclear exit in response to autophagy activation, and disrupts autophagy. Taken together, our data reveal DOR and TP53INP1 as dual regulators of transcription and autophagy, and identify two conserved regions in the DOR family that concentrate multiple functions crucial for autophagy and transcription. PMID:22470510

Role of Yb3+ ions on enhanced ~2.9 μm emission from Ho3+ ions in low phonon oxide glass system

PubMed Central

Balaji, Sathravada; Gupta, Gaurav; Biswas, Kaushik; Ghosh, Debarati; Annapurna, Kalyandurg

2016-01-01

The foremost limitation of an oxide based crystal or glass host to demonstrate mid- infrared emissions is its high phonon energy. It is very difficult to obtain radiative mid-infrared emissions from these hosts which normally relax non-radiatively between closely spaced energy levels of dopant rare earth ions. In this study, an intense mid-infrared emission around 2.9 μm has been perceived from Ho3+ ions in Yb3+/Ho3+ co-doped oxide based tellurite glass system. This emission intensity has increased many folds upon Yb3+: 985 nm excitation compared to direct Ho3+ excitations due to efficient excited state resonant energy transfer through Yb3+: 2F5/2 → Ho3+: 5I5 levels. The effective bandwidth (FWHM) and cross-section (σem) of measured emission at 2.9 μm are assessed to be 180 nm and 9.1 × 10−21 cm2 respectively which are comparable to other crystal/glass hosts and even better than ZBLAN fluoride glass host. Hence, this Ho3+/Yb3+ co-doped oxide glass system has immense potential for the development of solid state mid-infrared laser sources operating at 2.9 μm region. PMID:27374129

Dual functional NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ core-shell nanoparticles for cell temperature sensing and imaging

NASA Astrophysics Data System (ADS)

Shi, Zengliang; Duan, Yue; Zhu, Xingjun; Wang, Qiwei; Li, DongDong; Hu, Ke; Feng, Wei; Li, Fuyou; Xu, Chunxiang

2018-03-01

Lanthanide-doped up-conversion nanoparticles (UCNPs) provide a remote temperature sensing approach to monitoring biological microenvironments. In this research, the UCNPs of NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ with hexagonal (β)-phase were synthesized and applied in cell temperature sensing as well as imaging after surface modification with meso-2, 3-dimercaptosuccinic acid. In the core-shell UCNPs, Yb3+ ions were introduced as energy transfer media between sensitizers of Nd3+ and activators of Er3+ to improve Er3+emission and prevent their quenching behavior due to multiple energy levels of Nd3+. Under the excitations of 808 nm and 980 nm lasers, the NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+ nanoparticles exhibited an efficient green band with two emission peaks at 525 nm and 545 nm, respectively, which originated from the transitions of 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 for Er3+ ions. We demonstrate that an occurrence of good logarithmic linearity exists between the intensity ratio of these two emission peaks and the reciprocal of the inside or outside temperature of NIH-3T3 cells. A better thermal stability is proved through temperature-dependent spectra with a heating-cooling cycle. The obtained viability of NIH-3T3 cells is greater than 90% after incubations of about 12 and 24 (h), and they possess a lower cytotoxicity of UCNPs. This work provides a method for monitoring the cell temperature and its living state from multiple dimensions including temperature response, cell images and visual up-conversion fluorescent color.

Enhanced performance of Cr,Yb:YAG microchip laser by bonding Yb:YAG crystal.

PubMed

Cheng, Ying; Dong, Jun; Ren, Yingying

2012-10-22

Highly efficient, laser-diode pumped Yb:YAG/Cr,Yb:YAG self-Q-switched microchip lasers by bonding Yb:YAG crystal have been demonstrated for the first time to our best knowledge. The effect of transmission of output coupler (T(oc)) on the enhanced performance of Yb:YAG/Cr,Yb:YAG microchip lasers has been investigated and found that the best laser performance was achieved with T(oc) = 50%. Slope efficiency of over 38% was achieved. Average output power of 0.8 W was obtained at absorbed pump power of 2.5 W; corresponding optical-to-optical efficiency of 32% was obtained. Laser pulses with pulse width of 1.68 ns, pulse energy of 12.4 μJ, and peak power of 7.4 kW were obtained. The lasers oscillated in multi-longitudinal modes. The wide separation of longitudinal modes was attributed to the mode selection by combined etalon effect of Cr,Yb:YAG, Yb:YAG thin plates and output coupler. Stable periodical pulse trains at different pump power levels have been observed owing to the longitudinal modes coupling and competition.

Measurement of the minority carrier diffusion length and edge surface-recombination velocity in InP

NASA Technical Reports Server (NTRS)

Bailey, Sheila G.; Hakimzadeh, Roshanak

1993-01-01

A scanning electron microscope (SEM) was used to measure the electron (minority carrier) diffusion length (L(sub n)) and the edge surface-recombination velocity (V(sub s)) in zinc-doped Czochralski-grown InP wafers. Electron-beam-induced current (EBIC) profiles were obtained in specimens containing a Schottky barrier perpendicular to the scanned (edge) surface. An independent technique was used to measure V(sub s), and these values were used in a theoretical expression for normalized EBIC. A fit of the experimental data with this expression enabled us to determine L(sub n).

Efficient lasing in Yb:(YLa){sub 2}O{sub 3} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snetkov, I L; Mukhin, I B; Palashov, O V

2015-02-28

A high-optical-quality sample of Yb{sub 0.1}Y{sub 1.7}La{sub 0.2}O{sub 3} ceramics is prepared using a recently developed technique of selfpropagating high-temperature synthesis of rare-earth-doped yttrium oxide nanopowder from acetate – nitrates of metals. Its optical and spectral characteristics are studied, and quasi-cw lasing at a wavelength of 1033 nm is achieved with a power of 7 W and a slope efficiency of 25%. (lasers)

Structure and intense UV up-conversion emissions in RE3+-doped sol-gel glass-ceramics containing KYF4 nanocrystals

NASA Astrophysics Data System (ADS)

Yanes, A. C.; Santana-Alonso, A.; Méndez-Ramos, J.; del-Castillo, J.

2013-12-01

Transparent nano-glass-ceramics containing KYF4 nanocrystals were successfully obtained by the sol-gel method, doped with Eu3+ and co-doped with Yb3+ and Tm3+ ions. Precipitation of cubic KYF4 nanocrystals was confirmed by X-ray diffraction and high-resolution transmission electron microscope images. Excitation and emission spectra let us to discern between ions into KYF4 nanocrystals and those remaining in a glassy environment, supplemented with time-resolved photoluminescence decays, that also clearly reveal differences between local environments. Unusual high-energy up-conversion emissions in the UV range were obtained in Yb3+-Tm3+ co-doped samples, and involved mechanisms were discussed. The intensity of these high-energy emissions was analyzed as a function of Yb3+ concentration, heat treatment temperature of precursor sol-gel glasses and pump power, determining the optimum values for potential optical applications as highly efficient UV up-conversion materials in UV solid-state lasers.

Optical ridge waveguides in Er3+/Yb3+ co-doped phosphate glass produced by ion irradiation combined with femtosecond laser ablation for guided-wave green and red upconversion emissions

NASA Astrophysics Data System (ADS)

Chen, Chen; He, Ruiyun; Tan, Yang; Wang, Biao; Akhmadaliev, Shavkat; Zhou, Shengqiang; de Aldana, Javier R. Vázquez; Hu, Lili; Chen, Feng

2016-01-01

This work reports on the fabrication of ridge waveguides in Er3+/Yb3+ co-doped phosphate glass by the combination of femtosecond laser ablation and following swift carbon ion irradiation. The guiding properties of waveguides have been investigated at 633 and 1064 nm through end face coupling arrangement. The refractive index profile on the cross section of the waveguide has been constructed. The propagation losses can be reduced considerably after annealing treatment. Under the optical pump laser at 980 nm, the upconversion emission of both green and red fluorescence has been realized through the ridge waveguide structures.

Optimized design of Yb3+/Er3+-codoped cross-coupled integrated microring resonator arrays

NASA Astrophysics Data System (ADS)

Gǎlǎtus, Ramona; Vallés, Juan A.

2014-09-01

In this work the analytical model of the scattering response of a highly Yb3+/Er3+-codoped phosphate glass microring resonator array is developed. The microscopic statistical formalism is used to simulate its performance as a wavelengthselective amplifier. The performance of the integrated add-drop filter was investigated based on the signal transfer functions for Through and Drop ports, correlated the with gain coefficient and its dependence on pump power, signal power and Yb3+/Er3+- dopants concentration. In consequence, microring arrays with gain operating in the near infrared spectral range and, in particular, in the 1.5-mm wavelength band (emission band of Er-doped fiber amplifiers and lasers, already used in several bio/chemical sensing tasks) are highly attractive.

High-temperature-resistant distributed Bragg reflector fiber laser written in Er/Yb co-doped fiber.

PubMed

Guan, Bai-Ou; Zhang, Yang; Wang, Hong-Jun; Chen, Da; Tam, Hwa-Yaw

2008-03-03

We present a high-temperature-resistant distributed Bragg reflector fiber laser photowritten in Er/Yb codoped phosphosilicate fiber that is capable of long-term operation at 500 degrees C. Highly saturated Bragg gratings are directly inscribed into the Er/Yb fiber without hydrogen loading by using a 193 nm excimer laser and phase mask method. After annealing at elevated temperature, the remained gratings are strong enough for laser oscillation. The laser operates in robust single mode with output power more than 1 dBm and signal-to-noise ratio better than 70 dB over the entire temperature range from room temperature to 500 degrees C.

InP nanopore arrays for photoelectrochemical hydrogen generation.

PubMed

Li, Qiang; Zheng, Maojun; Zhang, Bin; Zhu, Changqing; Wang, Faze; Song, Jingnan; Zhong, Miao; Ma, Li; Shen, Wenzhong

2016-02-19

We report a facile and large-scale fabrication of highly ordered one-dimensional (1D) indium phosphide (InP) nanopore arrays (NPs) and their application as photoelectrodes for photoelectrochemical (PEC) hydrogen production. These InP NPs exhibit superior PEC performance due to their excellent light-trapping characteristics, high-quality 1D conducting channels and large surface areas. The photocurrent density of optimized InP NPs is 8.9 times higher than that of planar counterpart at an applied potential of +0.3 V versus RHE under AM 1.5G illumination (100 mW cm(-2)). In addition, the onset potential of InP NPs exhibits 105 mV of cathodic shift relative to planar control. The superior performance of the nanoporous samples is further explained by Mott-Schottky and electrochemical impedance spectroscopy ananlysis.

The influence of co-sintering Bi2O3 on Yb0.2Ce0.8O2-δ ceramic SOFC

NASA Astrophysics Data System (ADS)

Budiana, B.; Suasmoro, S.

2017-01-01

Ceramic Yb-doped CeO2 were prepared through two ways. First, sintering of mixed 20 mol % Yb2O3 and 80 mol % CeO2 at 1350 °C for 20 h and second sintering of mixed 96 mol % calcined Yb-doped CeO2 with 4 mol % Bi2O3 as a co-sintering agent at 1100 °C for 8h. Phase identification revealed that for the first sample was a cubic phase (a=5,3939Å) while the second sample showed three phases, CeO2 (cubic a=5,4254Å), YbxCe1-xO2-δ (cubic a=5,3980Å) and Bi5Yb3O12 (cubic a=10,5343Å). Cole-cole plot of impedance revealed 3 semicircles as marked of grain, grain boundary and electrode responses for B1 while for B2 showed two semicircles as marked of grain, grain boundary+electrode responses. Plot of log (σt) versus 1/T for both samples possed 2 activation energy regime, for the Sample B1 at T>650 °C Ea grain =1,01±0,04 eV and T<650 °C Ea grain =0,76±0,06 eV while for the sample B2 at T>650 °C, Ea grain =0,99±0,03 eV and T<650 °C Ea grain=0,70±0,09 eV.

Effect of silver nanoparticles on the 1.53 μm fluorescence in Er3+/Yb3+ codoped tellurite glasses

NASA Astrophysics Data System (ADS)

Wu, Libo; Zhou, Yaxun; Zhou, Zizhong; Cheng, Pan; Huang, Bo; Yang, Fengjing; Li, Jun

2016-07-01

Improving the spectroscopic properties of rare earth (RE) doped glass materials is a challenging task. In the present work the metallic silver nanoparticles (Ag NPs) were embedded into Er3+/Yb3+ codoped tellurite glasses with composition TeO2-Bi2O3-TiO2, prepared using melt-quenching and subsequent heat-treated techniques, and the improved effect of Ag NPs on the 1.53 μm band fluorescence of Er3+ ions was investigated. About 24 h heat-treatment of Er3+/Yb3+ codoped tellurite glass containing 1 mol % amount of AgNO3 at the temperature 370 °C yielded the well-dispersed and near-spherical Ag NPs with ∼11.4 nm average diameter as evidenced by transmission electron microscopy (TEM) image. The intense 1.53 μm band fluorescence was observed in the prepared Er3+/Yb3+ codoped tellurite glasses under the excitation of 980 nm and was further improved with the presence of Ag NPs in the glass matrix, which is attributed to the enhanced local electric field around doped RE ions induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced local electric field was well demonstrated by comparing the variation of emission spectra of hypersensitive probe Eu3+ ions in tellurite glasses with and without Ag NPs. From the Judd-Ofelt analysis, it was also found that the value of Ω6 intensity parameter increased slightly with the increase of Ag NPs concentration in a certain range, also confirming the possibility of realizing strong fluorescence emission. In addition, the amorphous structural nature was demonstrated by the measured X-ray diffraction (XRD) patterns with no sharp diffraction peak. The enhanced 1.53 μm band fluorescence indicates that the Er3+/Yb3+ codoped tellurite glass with an appropriate amount of Ag NPs is a promising candidate for the development of Er3+-doped fiber amplifiers (EDFAs) applied in the WDM systems.

Development of ytterbium-doped oxyfluoride glasses for laser cooling applications.

PubMed

Krishnaiah, Kummara Venkata; de Lima Filho, Elton Soares; Ledemi, Yannick; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman

2016-02-26

Oxyfluoride glasses doped with 2, 5, 8, 12, 16 and 20 mol% of ytterbium (Yb(3+)) ions have been prepared by the conventional melt-quenching technique. Their optical, thermal and thermo-mechanical properties were characterized. Luminescence intensity at 1020 nm under laser excitation at 920 nm decreases with increasing Yb(3+) concentration, suggesting a decrease in the photoluminescence quantum yield (PLQY). The PLQY of the samples was measured with an integrating sphere using an absolute method. The highest PLQY was found to be 0.99(11) for the 2 mol% Yb(3+): glass and decreases with increasing Yb(3+) concentration. The mean fluorescence wavelength and background absorption of the samples were also evaluated. Upconversion luminescence under 975 nm laser excitation was observed and attributed to the presence of Tm(3+) and Er(3+) ions which exist as impurity traces with YbF3 starting powder. Decay curves for the Yb(3+): (2)F5/2 → (2)F7/2 transition exhibit single exponential behavior for all the samples, although lifetime decrease was observed for the excited level of Yb(3+) with increasing Yb(3+) concentration. Also observed are an increase in the PLQY and a slight decrease in lifetime with increasing the pump power. Finally, the potential of these oxyfluoride glasses with high PLQY and low background absorption for laser cooling applications is discussed.

Photo-acoustic spectroscopy and quantum efficiency of Yb{sup 3+} doped alumino silicate glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhn, Stefan, E-mail: stefan.kuhn84@googlemail.com; Tiegel, Mirko; Herrmann, Andreas

2015-09-14

In this contribution, we analyze the effect of several preparation methods of Yb{sup 3+} doped alumino silicate glasses on their quantum efficiency by using photo-acoustic measurements in comparison to standard measurement methods including the determination via the fluorescence lifetime and an integrating sphere setup. The preparation methods focused on decreasing the OH concentration by means of fluorine-substitution and/or applying dry melting atmospheres, which led to an increase in the measured fluorescence lifetime. However, it was found that the influence of these methods on radiative properties such as the measured fluorescence lifetime alone does not per se give exact information aboutmore » the actual quantum efficiency of the sample. The determination of the quantum efficiency by means of fluorescence lifetime shows inaccuracies when refractive index changing elements such as fluorine are incorporated into the glass. Since fluorine not only eliminates OH from the glass but also increases the “intrinsic” radiative fluorescence lifetime, which is needed to calculate the quantum efficiency, it is difficult to separate lifetime quenching from purely radiative effects. The approach used in this contribution offers a possibility to disentangle radiative from non-radiative properties which is not possible by using fluorescence lifetime measurements alone and allows an accurate determination of the quantum efficiency of a given sample. The comparative determination by an integrating sphere setup leads to the well-known problem of reabsorption which embodies itself in the measurement of too low quantum efficiencies, especially for samples with small quantum efficiencies.« less

5 GHz fundamental repetition rate, wavelength tunable, all-fiber passively mode-locked Yb-fiber laser.

PubMed

Cheng, Huihui; Wang, Wenlong; Zhou, Yi; Qiao, Tian; Lin, Wei; Xu, Shanhui; Yang, Zhongmin

2017-10-30

A passively mode-locked Yb 3+ -doped fiber laser with a fundamental repetition rate of 5 GHz and wavelength tunable performance is demonstrated. A piece of heavily Yb 3+ -doped phosphate fiber with a high net gain coefficient of 5.7 dB/cm, in conjunction with a fiber mirror by directly coating the SiO 2 /Ta 2 O 5 dielectric films on a fiber ferrule is exploited for shortening the laser cavity to 2 cm. The mode-locked oscillator has a peak wavelength of 1058.7 nm, pulse duration of 2.6 ps, and the repetition rate signal has a high signal-to-noise ratio of 90 dB. Moreover, the wavelength of the oscillator is found to be continuously tuned from 1056.7 to 1060.9 nm by increasing the temperature of the laser cavity. Simultaneously, the repetition rate correspondingly decreases from 4.945874 to 4.945496 GHz. Furthermore, the long-term stability of the mode-locked operation in the ultrashort laser cavity is realized by exploiting temperature controls. This is, to the best of our knowledge, the highest fundamental pulse repetition rate for 1-μm mode-locked fiber lasers.

Lanthanide-doped upconversion nanocrystals: Synthesis and optical properties study

NASA Astrophysics Data System (ADS)

Sun, Qiang

Upconversion phosphor materials have attracted considerable attention in recent years for their potential applications in a wide range of fields, including three-dimensional displays technologies, bio-imaging and photovoltaics. This dissertation aims to develop novel lanthanide-doped upconversion luminescent nanomaterials by using wet chemistry methods. Considerable efforts have been devoted to manipulating the optical properties of the synthesized lanthanide-doped nanoparticles under excitation of different wavelengths, for example, 808, 980 and 1532 nm. In the first research work, a novel core-shell-shell design has been developed for finely tuning of energy migration upconversion of activators without long-lived mediated states, such as Eu3+ and Tb3+ upon excitation at 808 nm by using Nd3+ as sensitizer. Exquisite control the composition of each layer gives rise to maximized upconversion emissions of the activators. For example, with the use of core layer for energy harvesting (NaGdF4:Yb/Nd, active core), the optimal doping concentrations of Eu3+ and Tb3+ is fixed to 15 and 15 mol%, respectively. In contrast, active shell can also provide access to strong upconversion of Eu3+ and Tb3+ by doping Nd (40 mol%) into the outmost layer. Note that the effect of active shell is much stronger than active core in generating upconversion emissions of Eu3+ and Tb3+. Next, upconversion emission tuning of Er/Tm/Yb-doped NaYF4 upconversion nanoparticles has been conducted under excitation at 1532 nm. The output color of the nanoparticles is tunable by changing the doping levels of the lanthanides. With the use of core-shell design, the optical properties of the doped nanoparticles can be further optimized, for example, strongest upconversion emission was observed for NaYF4:Er(10 mol%) NaYF4:Er(0.5 mol%) with a relative emission of green-to-red of 1.2. This work provides a new dimension to control the color output of upconversion nanoparticles. It should be noted that the

Polarized spectral properties and 1.5-1.6 μm laser operation of Er:Sr3Yb2(BO3)4 crystal

NASA Astrophysics Data System (ADS)

Lin, F. L.; Huang, J. H.; Chen, Y. J.; Gong, X. H.; Lin, Y. F.; Luo, Z. D.; Huang, Y. D.

2013-10-01

Undoped and Er3+-doped Sr3Yb2(BO3)4 crystals were grown by the Czochralski method. Room temperature polarized spectral properties of the Er:Sr3Yb2(BO3)4 crystal were investigated. The efficiency of the energy transfer from Yb3+ to Er3+ ions in this crystal was calculated to be about 95%. End-pumped by a diode laser at 970 nm in a hemispherical cavity, a 0.75 W quasi-CW laser at 1.5-1.6 μm with a slope efficiency of 7% and an absorbed pump threshold of 3.8 W was achieved in a 0.5-mm-thick Z-cut crystal glued on a 5-mm-thick pure YAG crystal with UV-curable adhesive.

Role of Gd{sup 3+} ion on downshifting and upconversion emission properties of Pr{sup 3+}, Yb{sup 3+} co-doped YNbO{sub 4} phosphor and sensitization effect of Bi{sup 3+} ion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dwivedi, A.; Rai, S. B., E-mail: sbrai49@yahoo.co.in; Mishra, Kavita

Dual-mode luminescence (downshifting-DS and upconversion-UC) properties of Pr{sup 3+}/Yb{sup 3+} co-doped Y{sub 1−x}Gd{sub x}NbO{sub 4} (x = 0.0, 0.5, and 1.0) phosphors synthesized by solid state reaction technique have been explored with and without Gd{sup 3+} ion. The structural characterizations (XRD, SEM, and FTIR) confirm the pure phase of YNbO{sub 4} phosphor. Further, with the Gd{sup 3+} ion co-doping, the YNbO{sub 4} phosphors having a random shape and the large particle size are found to be transformed into nearly spherical shape particles with the reduced particle size. The optical band gaps (E{sub g}) of Y{sub 1−x}Gd{sub x}NbO{sub 4} (x = 0.00, 0.25, 0.50, andmore » 1.00) calculated from UV-Vis-NIR measurements are ∼3.69, 4.00, 4.38, and 4.44 eV, respectively. Moreover, YNbO{sub 4} phosphor is a promising blue emitting material, whereas Y{sub 1−x−y−z}Pr{sub y}Yb{sub z}Gd{sub x}NbO{sub 4} phosphor gives intense green, blue, and red emissions via dual-mode optical processes. The broad blue emission arises due to (NbO{sub 4}){sup 3−} group of the host with λ{sub ex} = 264 nm, whereas Pr{sup 3+} doped YNbO{sub 4} phosphor gives dominant red and blue emissions along with comparatively weak green emission on excitation with λ{sub ex} = 300 nm and 491 nm. The concentration dependent variation in emission intensity at 491 nm ({sup 3}P{sub 0}→{sup 3}H{sub 4} transition) and 612 nm ({sup 1}D{sub 2}→{sup 3}H{sub 4} transition); at 612 nm ({sup 1}D{sub 2}→{sup 3}H{sub 4} transition) and 658 nm ({sup 3}P{sub 0}→{sup 3}F{sub 2} transition) of Pr{sup 3+} ion in YNbO{sub 4} phosphor with λ{sub ex} = 300 nm and 491 nm excitations, respectively, has been thoroughly explored and explained by the cross-relaxation process through different channels. The sensitization effect of Bi{sup 3+} ion co-doping on DS properties of the phosphor has also been studied. The observed DS results have been optimized by

Guiding and amplification properties of rod-type photonic crystal fibers with sectioned core doping

NASA Astrophysics Data System (ADS)

Selleri, S.; Poli, F.; Passaro, D.; Cucinotta, A.; Lægsgaard, J.; Broeng, J.

2009-05-01

Rod-type photonic crystal fibers are large mode area double-cladding fibers with an outer diameter of few millimeters which can provide important advantages for high-power lasers and amplifiers. Numerical studies have recently demonstrated the guidance of higher-order modes in these fibers, which can worsen the output beam quality of lasers and amplifiers. In the present analysis a sectioned core doping has been proposed for Ybdoped rod-type photonic crystal fibers, with the aim to improve the higher-order mode suppression. A full-vector modal solver based on the finite element method has been applied to properly design the low refractive index ring in the fiber core, which can provide an increase of the differential overlap between the fundamental and the higher-order mode. Then, the gain competition among the guided modes along the Yb-doped rod-type fibers has been investigated with a spatial and spectral amplifier model. Simulation results have shown the effectiveness of the sectioned core doping in worsening the higher-order mode overlap on the doped area, thus providing an effective single-mode behavior of the Yb-doped rod-type photonic crystal fibers.

Backward optical gain originating from weak localization strengthened three-photon process in Er/Yb co-doped (Pb,La)(Zr,Ti)O₃ ceramics.

PubMed

Xu, Caixia; Zhang, Jingwen; Zou, Yingyin K; Zhao, Hua

2016-03-21

The enhancement of green upconverted emission from the Er³⁺/Yb³⁺ co-doped (Pb,La)(Zr,Ti)O₃ ceramic powder under a pumping light with a wavelength of 1480 nm was observed to be greater than 30 times that from the bulk of the same sample. Weak localization of light supported by the spatial profile of scattered light facilitated the three-photon process contributing to stronger green upconverted emission. Significant backward light amplification was also observed and studied in detail. Additionally, the distribution of the localization zones in the sample was investigated using a probing laser beam with a wavelength of 532 nm. The findings in this work could be used in improving the solar cell efficiency, modulating color, and designing smart devices.

Summary of Workshop on InP: Status and Prospects

NASA Technical Reports Server (NTRS)

Walters, R. J.; Weinberg, I.

1994-01-01

The primary objective of most of the programs in InP solar cells is the development of the most radiation hard solar cell technology. In the workshop, it was generally agreed that the goal is a cell which displays high radiation tolerance in a radiation environment equivalent to a 1 MeV electron fluence of about 10(exp 16)/sq cm. Furthermore, it is desired that the radiation response of the cell be essentially flat out to this fluence - i.e. that the power output of the cell not decrease from its beginning of life (BOL) value in this radiation environment. It was also agreed in the workshop that the manufacturability of InP solar cells needs to be improved. In particular, since InP wafers are relatively dense and brittle, alternative substrates need to be developed. Research on hetero-epitaxial InP cells grown on Si, Ge, and GaAs substrates is currently underway. The ultimate goal is to develop hetero-epitaxial InP solar cells using a cheap, strong, and lightweight substrate.

Yb:S-FAP Lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schaffers, K I

It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass,more » diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.« less

Study by AES, EELS Spectroscopy of electron Irradiation on InP and InPO4/InP in comparison with Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Lounis, Z.; Bouslama, M.; Hamaida, K.; Jardin, C.; Abdellaoui, A.; Ouerdane, A.; Ghaffour, M.; Berrouachedi, N.

2012-02-01

We give the great interest to characterise the InP and InPO4/InP submitted to electron beam irradiation owing to the Auger Electron Spectroscopy (AES) associated to both methods Electron Energy Loss Spectroscopy (EELS). The incident electron produces breaking of (In-P) chemical bonds. The electron beam even acts to stimulate oxidation of InP surface involving on the top layers. Other, the oxide InPO4 developed on InP does appear very sensitive to the irradiation due to electron beam shown by the monitoring of EELS spectra recorded versus the irradiated times of the surface. There appears a new oxide thought to be In2O3. We give the simulation methods Casino (Carlo simulation of electron trajectory in solids) for determination with accuracy the loss energy of backscattered electrons and compared with reports results have been obtained with EELS Spectroscopy. These techniques of spectroscopy alone do not be able to verify the affected depth during interaction process. So, using this simulation method, we determine the interaction of electrons in the matter.

Young's Modulus of Wurtzite and Zinc Blende InP Nanowires.

PubMed

Dunaevskiy, Mikhail; Geydt, Pavel; Lähderanta, Erkki; Alekseev, Prokhor; Haggrén, Tuomas; Kakko, Joona-Pekko; Jiang, Hua; Lipsanen, Harri

2017-06-14

The Young's modulus of thin conical InP nanowires with either wurtzite or mixed "zinc blende/wurtzite" structures was measured. It has been shown that the value of Young's modulus obtained for wurtzite InP nanowires (E [0001] = 130 ± 30 GPa) was similar to the theoretically predicted value for the wurtzite InP material (E [0001] = 120 ± 10 GPa). The Young's modulus of mixed "zinc blende/wurtzite" InP nanowires (E [111] = 65 ± 10 GPa) appeared to be 40% less than the theoretically predicted value for the zinc blende InP material (E [111] = 110 GPa). An advanced method for measuring the Young's modulus of thin and flexible nanostructures is proposed. It consists of measuring the flexibility (the inverse of stiffness) profiles 1/k(x) by the scanning probe microscopy with precise control of loading force in nanonewton range followed by simulations.

Tunable upconversion luminescence of monodisperse Y2O3: Er3+/Yb3+/Tm3+ nanoparticles

NASA Astrophysics Data System (ADS)

Wu, Qibai; Lin, Shaoteng; Xie, Zhongxiang; Zhang, Liqing; Qian, Yannan; Wang, Yaodong; Zhang, Haiyan

2017-12-01

Monodisperse Y2O3: Er3+/Yb3+/Tm3+ nanoparticles with various dopant concentrations have been synthesized successfully by a homogeneous precipitation method. Their phase structures and surface morphologies have been characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The diversities of upconversion luminescence spectra and CIE coordinates of prepared samples are investigated in detail at room temperature under 980 nm excitation. Through adjusting the concentrations of Yb3+, Tm3+ and Er3+ ions, three upconversion emission bands in red, green and blue region could be tunable to achieve the color of interest and near white light emission can be obtained in the tri-doped Y2O3 nanoparticles for a variety of application.

Near infrared emission of TbAG:Ce{sup 3+},Yb{sup 3+} phosphor for solar cell applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meshram, N. D., E-mail: meshramnileshsd@gmail.com; Yadav, P. J., E-mail: yadav.pooja75@yahoo.in; Pathak, A. A., E-mail: aapathak@yahoo.com

2016-05-06

Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimatedmore » to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr{sup 3+}, Gd{sup 3+},Gd{sup 3+}–Eu{sup 3+}, and Er{sup 3+}–Tb{sup 3+} had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb{sup 3+}–Yb{sup 3+}, Pr{sup 3+}–Yb{sup 3+}, and Tm{sup 3+}–Yb{sup 3+} has been reported. The Yb{sup 3+} ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb{sup 3+} is close to 100% and the energy of the only excited level of Yb{sup 3+} (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce{sup 3+}-doped Tb{sub 3}Al{sub 5}O{sub 12} (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300–500 nm due to strong ligand field and high luminescent quantum efficiency

P/N InP solar cells on Ge wafers

NASA Technical Reports Server (NTRS)

Wojtczuk, Steven; Vernon, Stanley; Burke, Edward A.

1994-01-01

Indium phosphide (InP) P-on-N one-sun solar cells were epitaxially grown using a metalorganic chemical vapor deposition process on germanium (Ge) wafers. The motivation for this work is to replace expensive InP wafers, which are fragile and must be thick and therefore heavy, with less expensive Ge wafers, which are stronger, allowing use of thinner, lighter weight wafers. An intermediate InxGs1-xP grading layer starting as In(0.49)Ga(0.51) at the GaAs-coated Ge wafer surface and ending as InP at the top of the grading layer (backside of the InP cell) was used to attempt to bend some of the threading dislocations generated by lattice-mismatch between the Ge wafer and InP cell so they would be harmlessly confined in this grading layer. The best InP/Ge cell was independently measured by NASA-Lewis with a one-sun 25 C AMO efficiently measured by NASA-Lewis with a one-circuit photocurrent 22.6 mA/sq cm. We believe this is the first published report of an InP cell grown on a Ge wafer. Why get excited over a 9 percent InP/Ge cell? If we look at the cell weight and efficiency, a 9 percent InP cell on an 8 mil Ge wafer has about the same cell power density, 118 W/kg (BOL), as the best InP cell ever made, a 19 percent InP cell on an 18 mil InP wafer, because of the lighter Ge wafer weight. As cell panel materials become lighter, the cell weight becomes more important, and the advantage of lightweight cells to the panel power density becomes more important. In addition, although InP/Ge cells have a low beginning-of-life (BOL) efficiency due to dislocation defects, the InP/Ge cells are very radiation hard (end-of-life power similar to beginning-of-life). We have irradiated an InP/Ge cell with alpha particles to an equivalent fluence of 1.6 x 10(exp 16) 1 MeV electrons/sq cm and the efficiency is still 83 percent of its BOL value. At this fluence level, the power output of these InP/Ge cells matches the GaAs/Ge cell data tabulated in the JPL handbook. Data are presented

Electronic Structure of Ytterbium-Doped Strontium Fluoroapatite: Photoemission and Photoabsorption Investigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, Art J.; Van Buuren, Tony W.; Bostedt, C

X-ray photoemission and x-ray photoabsorption were used to study the composition and the electronic structure of ytterbium-doped strontium fluoroapatite (Yb:S-FAP). High resolution photoemission measurements on the valence band electronic structure and Sr 3d, P 2p and 2s, Yb 4d and 4p, F 1s and O 1s core lines were used to evaluate the surface and near surface chemistry of this fluoroapatite. Element specific density of unoccupied electronic states in Yb:S-FAP were probed by x-ray absorption spectroscopy (XAS) at the Yb 4d (N4,5-edge), Sr 3d (M4,5-edge), P 2p (L2,3-edge), F 1s and O 1s (K-edges) absorption edges. These results provide themore » first measurements of the electronic structure and surface chemistry of this material.« less

Characterization of bubble core and cloudiness in Yb3+:Sr5(PO4)3F crystals using Micro-Raman spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Y; Roy, U N; Bai, L

Ytterbium doped strontium fluoroapatite Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F (Yb: S-FAP) crystals have been used in High Average Power Laser systems as gain medium. Growth induced defects associated with the crystal often affect their performance. In order to improve the crystal quality and its optical applications, it is imperative to understand the nature of these defects. In this study, we utilize Micro-Raman spectroscopy to characterize two common growth-induced defects: bubble core and cloudiness. We find the bubble core consist of voids and microcrystals of Yb: S-FAP. These microcrystals have very different orientation from that of the pure crystal outside themore » bubble core. In contrast to a previous report, neither Sr{sub 3}(PO{sub 4}){sub 2} nor Yb{sub 2}O{sub 3} are observed in the bubble core regions. On the other hand, the cloudy regions are made up of the host materials blended with a structural deformation along with impurities which include CaCO{sub 3}, YbPO{sub 4}, SrHPO{sub 4} and Sr{sub 2}P{sub 2}O{sub 7}. The impurities are randomly distributed in the cloudy regions. This analysis is necessary for understanding and eliminating these growth defects in Yb:S-FAP crystals.« less

Fabrication and evaluation of chitosan/NaYF4:Yb3+/Tm3+ upconversion nanoparticles composite beads based on the gelling of Pickering emulsion droplets.

PubMed

Yan, Huiqiong; Chen, Xiuqiong; Shi, Jia; Shi, Zaifeng; Sun, Wei; Lin, Qiang; Wang, Xianghui; Dai, Zihao

2017-02-01

The rare earth ion doped upconversion nanoparticles (UCNPs) synthesized by hydrophobic organic ligands possess poor solubility and low fluorescence quantum yield in aqueous media. To conquer this issue, NaYF 4 :Yb 3+ /Tm 3+ UCNPs, synthesized by a hydrothermal method, were coated with F127 and then assembled with chitosan to fabricate the chitosan/NaYF 4 :Yb 3+ /Tm 3+ composite beads (CS/NaYF 4 :Yb 3+ /Tm 3+ CBs) by Pickering emulsion system. The characterization results revealed that the as-synthesized NaYF 4 :Yb 3+ /Tm 3+ UCNPs with an average size of 20nm exhibited spherical morphology, high crystallinity and characteristic emission upconversion fluorescence with an overall blue color output. The NaYF 4 :Yb 3+ /Tm 3+ UCNPs were successfully conjugated on the surface of chitosan beads by the gelling of emulsion droplets. The resultant CS/NaYF 4 :Yb 3+ /Tm 3+ CBs showed good upconversion luminescent property, drug-loading capacity, release performance and excellent biocompatibility, exhibiting great potentials in targeted drug delivery and tissue engineering with potential tracking capability and lasting release performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of ytterbium-doped oxyfluoride glasses for laser cooling applications

PubMed Central

Krishnaiah, Kummara Venkata; Soares de Lima Filho, Elton; Ledemi, Yannick; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman

2016-01-01

Oxyfluoride glasses doped with 2, 5, 8, 12, 16 and 20 mol% of ytterbium (Yb3+) ions have been prepared by the conventional melt-quenching technique. Their optical, thermal and thermo-mechanical properties were characterized. Luminescence intensity at 1020 nm under laser excitation at 920 nm decreases with increasing Yb3+ concentration, suggesting a decrease in the photoluminescence quantum yield (PLQY). The PLQY of the samples was measured with an integrating sphere using an absolute method. The highest PLQY was found to be 0.99(11) for the 2 mol% Yb3+: glass and decreases with increasing Yb3+ concentration. The mean fluorescence wavelength and background absorption of the samples were also evaluated. Upconversion luminescence under 975 nm laser excitation was observed and attributed to the presence of Tm3+ and Er3+ ions which exist as impurity traces with YbF3 starting powder. Decay curves for the Yb3+: 2F5/2 → 2F7/2 transition exhibit single exponential behavior for all the samples, although lifetime decrease was observed for the excited level of Yb3+ with increasing Yb3+ concentration. Also observed are an increase in the PLQY and a slight decrease in lifetime with increasing the pump power. Finally, the potential of these oxyfluoride glasses with high PLQY and low background absorption for laser cooling applications is discussed. PMID:26915817

Zero-field quantum critical point in Ce0.91Yb0.09CoIn5

NASA Astrophysics Data System (ADS)

Singh, Y. P.; Adhikari, R. B.; Haney, D. J.; White, B. D.; Maple, M. B.; Dzero, M.; Almasan, C. C.

2018-05-01

We present results of specific heat, electrical resistance, and magnetoresistivity measurements on single crystals of the heavy-fermion superconducting alloy Ce0.91Yb0.09CoIn5 . Non-Fermi-liquid to Fermi-liquid crossovers are clearly observed in the temperature dependence of the Sommerfeld coefficient γ and resistivity data. Furthermore, we show that the Yb-doped sample with x =0.09 exhibits universality due to an underlying quantum phase transition without an applied magnetic field by utilizing the scaling analysis of γ . Fitting of the heat capacity and resistivity data based on existing theoretical models indicates that the zero-field quantum critical point is of antiferromagnetic origin. Finally, we found that at zero magnetic field the system undergoes a third-order phase transition at the temperature Tc 3≈7 K.

Electron guns and collectors developed at INP for electron cooling devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharapa, A.N.; Shemyakin, A.V.

1997-09-01

Institute of Nuclear Physics (INP) has a rich experience in designing electron guns and collectors for electron cooling devices. This paper is a review of the experience of several INP research groups in this field. Some results obtained at INP for systems without a guiding magnetic field are also discussed.

Upconversion luminescence of CsScF4 crystals doped with erbium and ytterbium

NASA Astrophysics Data System (ADS)

Ikonnikov, D. A.; Voronov, V. N.; Molokeev, M. S.; Aleksandrovsky, A. S.

2016-10-01

Tetragonal CsScF4 crystals doped with (5 at.%) Er and Er/Yb (0.5 at.%/5 at.%) are grown and their crystal structure is determined to belong to Pmmn space group. Er and Yb ions are shown to occupy distorted octahedral Sc sites with the center of inversion. Bright visible upconversion luminescence was observed under 970-980 nm pumping with red (4F9/2), yellow (4S3/2) and green (2H11/2) bands of comparable intensity. UCL tuning curves maximize at 972 nm (CSF:Er) and at 969.7 nm (CSF:Er,Yb) pumping wavelengths. Different ratios between yellow-green and red luminescence intensities in CSF:Er and CSF:Er, Yb are explained by contribution of cross-relaxation in CSF:Er UCL. UC in CSF:Er is a three stage process while UC in CSF:Er, Yb is a two stage process. The peculiarities of power dependences are explained by the power-dependent repopulation between starting levels of UC.

A "win-win" nanoplatform: TiO2:Yb,Ho,F for NIR light-induced synergistic therapy and imaging.

PubMed

Zhou, Jie; Luo, Pei; Sun, Chong; Meng, Lingchang; Ye, Weiran; Chen, Shanshan; Du, Bin

2017-03-23

To avoid the defect of low energy transfer efficiency in core-shell UCNP-TiO 2 NPs, doping rare earth into TiO 2 and improving the photocatalytic activity of TiO 2 itself under Vis-NIR light might be a more direct and efficient strategy for high 1 O 2 production. Here, we designed a TiO 2 :Yb,Ho,F-β-CD@DTX/HA nanoplatform using TiO 2 :Yb,Ho,F as the core, β-CD as the drug carrier, hyaluronic acid (HA) as the capping agent and target, and then applied it for 808 nm induced photodynamic-chemotherapy and 980 nm upconversion fluorescence/MR imaging. The results were as follows: (i) for TiO 2 as a photosensitizer, after doping Yb, Ho, F into TiO 2 , it could directly generate reactive oxygen species under an 808 nm laser; the dopants enhanced the absorption under the UV-Vis-NIR region and increased the electron-hole pair separation. (ii) For TiO 2 as the upconversion host, F and Ho also endowed TiO 2 :Yb,Ho,F with enhanced upconversion fluorescence under a 980 nm laser and T 2 -MRI contrast performance (r 2 = 30.71 mM -1 s -1 ), respectively, thus, facilitating imaging for deep tissues. (iii) The HA shell outside of β-CD prevented the unexpected leaking of DTX, which improved the target abilities and achieved the enzyme-responsive drug release. The in vitro and in vivo studies also demonstrated the nanosystem could efficiently suppress tumor growth by combination therapy and had excellent imaging (UCL/MR) ability. Particularly, our work was the first example that utilized TiO 2 simultaneously as a photosensitizer and upconversion host, which simplified the core-shell UCNP-TiO 2 nanocomposites and reached a "win-win" cooperation in NIR-induced photodynamic therapy and UCL imaging.

Color-tunable up-conversion emission in Y2O3:Yb3+, Er3+ nanoparticles prepared by polymer complex solution method

PubMed Central

2013-01-01

Abstract Powders of Y2O3 co-doped with Yb3+ and Er3+ composed of well-crystallized nanoparticles (30 to 50 nm in diameter) with no adsorbed ligand species on their surface are prepared by polymer complex solution method. These powders exhibit up-conversion emission upon 978-nm excitation with a color that can be tuned from green to red by changing the Yb3+/Er3+ concentration ratio. The mechanism underlying up-conversion color changes is presented along with material structural and optical properties. PACS 42.70.-a, 78.55.Hx, 78.60.-b PMID:23522083

Diffusion length damage coefficient and annealing studies in proton-irradiated InP

NASA Technical Reports Server (NTRS)

Hakimzadeh, Roshanak; Vargas-Aburto, Carlos; Bailey, Sheila G.; Williams, Wendell

1993-01-01

We report on the measurement of the diffusion length damage coefficient (K(sub L)) and the annealing characteristics of the minority carrier diffusion length (L(sub n)) in Czochralski-grown zinc-doped indium phosphide (InP), with a carrier concentration of 1 x 10(exp l8) cm(exp -3). In measuring K(sub L) irradiations were made with 0.5 MeV protons with fluences ranging from 1 x 10(exp 11) to 3 x 10(exp 13) cm(exp -2). Pre- and post-irradiation electron-beam induced current (EBIC) measurements allowed for the extraction of L(sub n) from which K(sub L) was determined. In studying the annealing characteristics of L(sub n) irradiations were made with 2 MeV protons with fluence of 5 x 10(exp 13) cm(exp -2). Post-irradiation studies of L(sub n) with time at room temperature, and with minority carrier photoinjection and forward-bias injection were carried out. The results showed that recovery under Air Mass Zero (AMO) photoinjection was complete. L(sub n) was also found to recover under forward-bias injection, where recovery was found to depend on the value of the injection current. However, no recovery of L(sub n) after proton irradiation was observed with time at room temperature, in contrast to the behavior of 1 MeV electron-irradiated InP solar cells reported previously.

Performance, Defect Behavior and Carrier Enhancement in Low Energy, Proton Irradiated p(+)nn(+) InP Solar Cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Rybicki, G. C.; Vargas-Aburto, C.; Jain, R. K.; Scheiman, D.

1994-01-01

InP p(+)nn(+) cells, processed by MOCVD, were irradiated by 0.2 MeV protons and their performance and defect behavior observed to a maximum fluence of 10(exp 13)/sq cm. Their radiation induced degradation, over this fluence range, was considerably+less than observed for similarly irradiated, diffused junction n p InP cells. Significant degradation occurred in both the cell's emitter and base regions the least degradation occurring in the depletion region. A significant increase in series resistance occurs at the highest fluenc.e. Two majority carrier defect levels, E7 and E10, are observed by DLTS with activation energies at (E(sub C) - 0.39)eV and (E(sub C) - 0.74)eV respectively. The relative concentration of these defects differs considerably from that observed after 1 MeV electron irradiation. An increased carrier concentration in the cell's n-region was observed at the highest proton fluence, the change in carrier concentration being insignificant at the lower fluences. In agreement with previous results, for 1 and 1.5 MeV electron irradiated InP p(+)n junctions, the defect level E10 is attributed to a complex between zinc, diffused into the n-region from the zinc doped emitter, and a radiation induced defect. The latter is assumed to be either a phosphorus vacancy or interstitial. The increased, or enhanced carrier concentration is attributed to this complex acting as a donor.

Cooperative down-conversion of UV light in disordered scheelitelike Yb-doped NaGd(MoO4)2 and NaLa(MoO4)2 crystals

NASA Astrophysics Data System (ADS)

Subbotin, K. A.; Osipova, Yu. N.; Lis, D. A.; Smirnov, V. A.; Zharikov, E. V.; Shcherbakov, I. A.

2017-07-01

Concentration series of disordered scheelitelike Yb:NaGd(MoO4)2 and Yb:NaLa(MoO4)2 single crystals are grown by the Czochralski method. The actual concentrations of Yb3+ ions in the crystals are determined by optical-absorption spectroscopy. The luminescence of Yb3+ ions in these crystals in the region of 1 μm is studied under UV and IR excitation. In the case of UV excitation, this luminescence appears as a result of nonradiative excited state energy transfer from donor centers of unknown nature to ytterbium. The character of the concentration dependence of Yb3+ luminescence indicates that the energy transfer at high Yb concentrations occurs with active participation of a cooperative mechanism, according to which the excitation energy of one donor center is transferred simultaneously to two Yb3+ ions. In other words, the quantum yield of this transfer exceeds unity, which can be used to increase the efficiency of crystalline silicon (c-Si) solar cells.

CNPq/INPE-LANDSAT system

NASA Technical Reports Server (NTRS)

Debarrosaguirre, J. L.

1985-01-01

The current status of the Brazilian LANDSAT facilities operated by Instituto de Pesquisas Espaciais (INPE) and the results achieved during the period from October 1, 1984 to August 31, 1985 are presented. INPE's Receiving Station at Cuiaba, MT, operates normally the two tracking and receiving systems it has installed, the old one (1973) for Band S and the new one (February 1983) for dual S- and X-band. Both MSS and TM recording capabilities are functional. Support to the NASA Backup Plan for MSS data also remains active. Routine recordings are being made for LANDSAT-5 only, for both MSS and TM. Originally, MSS was recorded over the full acquisition range. However, since December, 1984, due to further reduction of operational expenses, both instruments are being recorded over Brazilian territory only.

Ti : sapphire laser synchronised with femtosecond Yb pump laser via nonlinear pulse coupling in Ti : sapphire active medium

NASA Astrophysics Data System (ADS)

Didenko, N. V.; Konyashchenko, A. V.; Konyashchenko, D. A.; Kostryukov, P. V.; Kuritsyn, I. I.; Lutsenko, A. P.; Mavritskiy, A. O.

2017-02-01

A laser system utilising the method of synchronous pumping of a Ti : sapphire laser by a high-power femtosecond Yb3+-doped laser is described. The pulse repetition rate of the Ti : sapphire laser is successfully locked to the repetition rate of the Yb laser for more than 6 hours without the use of any additional electronics. The measured timing jitter is shown to be less than 1 fs. A simple qualitative model addressing the synchronisation mechanism utilising the cross-phase modulation of oscillation and pump pulses within a Ti : sapphire active medium is proposed. Output parameters of the Ti : sapphire laser as functions of its cavity length are discussed in terms of this model.

Crystal field excitations from Yb3 + ions at defective sites in highly stuffed Yb2Ti2O7

NASA Astrophysics Data System (ADS)

Sala, G.; Maharaj, D. D.; Stone, M. B.; Dabkowska, H. A.; Gaulin, B. D.

2018-06-01

The pyrochlore magnet Yb2Ti2O7 has been proposed as a quantum spin ice candidate, a spin liquid state expected to display emergent quantum electrodynamics with gauge photons among its elementary excitations. However, Yb2Ti2O7 's ground state is known to be very sensitive to its precise stoichiometry. Powder samples, produced by solid-state synthesis at relatively low temperatures, tend to be stoichiometric, while single crystals grown from the melt tend to display weak "stuffing" wherein ˜2 % of the Yb3 +, normally at the A site of the A2B2O7 pyrochlore structure, reside as well at the B site. In such samples Yb3 + ions should exist in defective environments at low levels and be subjected to crystalline electric fields very different from those at the stoichiometric A sites. Neutron scattering measurements of Yb3 + in four compositions of Yb2 +xTi2 -xO7 -y show the spectroscopic signatures for these defective Yb3 + ions and explicitly demonstrate that the spin anisotropy of the Yb3 + moment changes from X Y -like for stoichiometric Yb3 + to Ising-like for "stuffed" B site Yb3 + or for A site Yb3 + in the presence of oxygen vacancies.

Thermometry properties of Er, Yb-Gd2O2S microparticles: dependence on the excitation mode (cw versus pulsed excitation) and excitation wavelength (980 nm versus 1500 nm)

NASA Astrophysics Data System (ADS)

Avram, Daniel; Tiseanu, Carmen

2018-04-01

Herein, we present a first report on the luminescence thermometry properties of Er, Yb doped Gd2O2S microparticles under near infrared up-conversion excitation at 980 and 1500 nm measured in the 280-800 K interval. The thermometry properties are assessed using both cw and ns pulsed excitation as well as tuning the excitation wavelength across Yb and Er absorption profiles. For low cw (300 mW cm-1) and pulsed ns (400 ÷ 550 mW cm-1) excitation modes, no thermal load is observed. At room-temperature (280 K), the maximum relative sensitivity values are comparable under pulsed excitation at 980 and 1500 nm, around ˜0.01 and ˜0.008% K-1, respectively. In addition, a relative intense up-conversion emission at 980 nm under excitation at 1500 nm is measured. Our findings evidence attractive up-conversion and thermometry properties Er, Yb doped Gd2O2S under near-infrared excitation and highlight the need to explore further these properties in the nanoparticulate regime.

Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Page, R.H.; Schaffers, K.I.; Waide, P.A.

We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beammore » profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.« less

Three-Stage InP Submillimeter-Wave MMIC Amplifier

NASA Technical Reports Server (NTRS)

Pukala, David; Samoska, Lorene; Man, King; Gaier, Todd; Deal, William; Lai, Richard; Mei, Gerry; Makishi, Stella

2008-01-01

A submillimeter-wave monolithic integrated- circuit (S-MMIC) amplifier has been designed and fabricated using an indium phosphide (InP) 35-nm gate-length high electron mobility transistor (HEMT) device, developed at Northrop Grumman Corporation. The HEMT device employs two fingers each 15 micrometers wide. The HEMT wafers are grown by molecular beam epitaxy (MBE) and make use of a pseudomorphic In0.75Ga0.25As channel, a silicon delta-doping layer as the electron supply, an In0.52Al0.48As buffer layer, and an InP substrate. The three-stage design uses coplanar waveguide topology with a very narrow ground-to-ground spacing of 14 micrometers. Quarter-wave matching transmission lines, on-chip metal-insulator-metal shunt capacitors, series thin-film resistors, and matching stubs were used in the design. Series resistors in the shunt branch arm provide the basic circuit stabilization. The S-MMIC amplifier was measured for S-parameters and found to be centered at 320 GHz with 13-15-dB gain from 300-345 GHz. This chip was developed as part of the DARPA Submillimeter Wave Imaging Focal Plane Technology (SWIFT) program (see figure). Submillimeter-wave amplifiers could enable more sensitive receivers for earth science, planetary remote sensing, and astrophysics telescopes, particularly in radio astronomy, both from the ground and in space. A small atmospheric window at 340 GHz exists and could enable ground-based observations. However, the submillimeter-wave regime (above 300 GHz) is best used for space telescopes as Earth s atmosphere attenuates most of the signal through water and oxygen absorption. Future radio telescopes could make use of S-MMIC amplifiers for wideband, low noise, instantaneous frequency coverage, particularly in the case of heterodyne array receivers.

InP concentrator solar cells for space applications

NASA Technical Reports Server (NTRS)

Ward, J. S.; Wanlass, M. W.; Coutts, T. J.; Emery, K. A.

1991-01-01

The design, fabrication, and characterization of high-performance, n(+)/p InP shallow-homojunction (SHJ) concentrator solar cells is described. The InP device structures were grown by atmospheric-pressure metalorganic vapor phase epitaxy (APMOVPE). A preliminary assessment of the effects of grid collection distance and emitter sheet resistance on cell performance is presented. At concentration ratios of over 100, cells with AM0 efficiencies in excess of 21 percent at 25 C and 19 percent at 80 C are reported. These results indicate that high-efficiency InP concentrator cells can be fabricated using existing technologies. The performance of these cells as a function of temperature is discussed, and areas for future improvement are outlined.

Graphene enhanced field emission from InP nanocrystals.

PubMed

Iemmo, L; Di Bartolomeo, A; Giubileo, F; Luongo, G; Passacantando, M; Niu, G; Hatami, F; Skibitzki, O; Schroeder, T

2017-12-08

We report the observation of field emission (FE) from InP nanocrystals (NCs) epitaxially grown on an array of p-Si nanotips. We prove that FE can be enhanced by covering the InP NCs with graphene. The measurements are performed inside a scanning electron microscope chamber with a nano-controlled W-thread used as an anode. We analyze the FE by Fowler-Nordheim theory and find that the field enhancement factor increases monotonically with the spacing between the anode and the cathode. We also show that InP/p-Si junction has a rectifying behavior, while graphene on InP creates an ohmic contact. Understanding the fundamentals of such nanojunctions is key for applications in nanoelectronics.

Lateral spreading of Au contacts on InP

NASA Technical Reports Server (NTRS)

Fatemi, Navid S.; Weizer, Victor G.

1990-01-01

The contact spreading phenomenon observed when small area Au contacts on InP are annealed at temperatures above about 400 C was investigated. It was found that the rapid lateral expansion of the contact metallization which consumes large quantities of InP during growth is closely related to the third stage in the series of solid state reactions that occur between InP and Au, i.e., to the Au3In-to-Au9In4 transition. Detailed descriptions are presented of both the spreading process and the Au3In-to-Au9In4 transition along with arguments that the two processes are manifestations of the same basic phenomenon.

Graphene enhanced field emission from InP nanocrystals

NASA Astrophysics Data System (ADS)

Iemmo, L.; Di Bartolomeo, A.; Giubileo, F.; Luongo, G.; Passacantando, M.; Niu, G.; Hatami, F.; Skibitzki, O.; Schroeder, T.

2017-12-01

We report the observation of field emission (FE) from InP nanocrystals (NCs) epitaxially grown on an array of p-Si nanotips. We prove that FE can be enhanced by covering the InP NCs with graphene. The measurements are performed inside a scanning electron microscope chamber with a nano-controlled W-thread used as an anode. We analyze the FE by Fowler-Nordheim theory and find that the field enhancement factor increases monotonically with the spacing between the anode and the cathode. We also show that InP/p-Si junction has a rectifying behavior, while graphene on InP creates an ohmic contact. Understanding the fundamentals of such nanojunctions is key for applications in nanoelectronics.

Rugosity and hardness determination in obsidianus lapis for the design of an Yb3+-doped fiber laser

NASA Astrophysics Data System (ADS)

Alvarez-Chavez, J. A.; Aguilar-Morales, A. I.; Perez-Sanchez, G. G.; Morales-Ramirez, A. J.

2015-01-01

Obsidianus lapis is a volcanic rock that has been worked into tools for cutting or weaponry by Teotihuacan people for hundreds of years. Currently, it is used in jewelry or for house decorative items such as elaborated sculptures. From the physico-chemical properties point of view, obsidianus lapis is considered a glass as its composition is 80% silicon dioxide. In México, there are different kinds of obsidianus lapis which are classified according to its colour: rainbow, black, brown, red, silver, golden and snowflake. The traditional grinding process for working with obsidianus lapis includes fixed grinders and sandpaper for the polishing process, where the craftsman grinds the rock manually for obtaining a variety of shapes. Laser processing of natural stones is a relatively new area. We propose the use of an Yb3+-doped fibre laser for cutting and ablating obsidianus lapis into spherical, rectangular and oval shapes. By means of a theoretical analysis of roughness and hardness, which affect the different surfaces and final shapes, and by considering the changes in material temperature during laser interaction, this work will focus on parameter determination such as: laser fluence, incidence angle, laser average power and peak pulse energy, from the proposed Q-switched fibre laser design. Full optical, hardness and rugosity, initial and final characterization will be included in the presentation.

Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses for ∼1.2 μm laser applications

NASA Astrophysics Data System (ADS)

Wang, Shunbin; Li, Chengzhi; Yao, Chuanfei; Jia, Shijie; Jia, Zhixu; Qin, Guanshi; Qin, Weiping

2017-02-01

Intense ∼1.2 μm fluorescence is observed in Ho3+/Yb3+ co-doped TeO2-BaF2-Y2O3 glasses under 915 nm laser diode excitation. The 1.2 μm emission can be ascribed to the transition 5I6→5I8 of Ho3+. With the introducing of BaF2, the content of OH in the glasses drops markedly, and the 1.2 μm emission intensity increases gradually as increasing the concentration percentage of BaF2. Furthermore, microstructured fibers based on the TeO2-BaF2-Y2O3 glasses are fabricated by using a rod-in-tube method, and a relative positive gain of ∼9.42 dB at 1175.3 nm is obtained in a 5 cm long fiber.

Photoemission and Photoabsorption Investigation of the Electronic Structure of Ytterbium Doped Strontium Fluoroapatite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nelson, A J; van Buuren, T; Bostedt, C

X-ray photoemission and x-ray photoabsorption were used to study the composition and the electronic structure of ytterbium doped strontium fluoroapatite (Yb:S-FAP). High resolution photoemission measurements on the valence band electronic structure was used to evaluate the density of occupied states of this fluoroapatite. Element specific density of unoccupied electronic states in Yb:S-FAP were probed by x-ray absorption spectroscopy (XAS) at the Yb 4d (N{sub 4,5}-edge), Sr 3d (M{sub 4,5}-edge), P 2p (L{sub 2,3}-edge), F 1s and O 1s (K-edges) absorption edges. These results provide the first measurements of the electronic structure and surface chemistry of this material.

Magnetic and upconverted luminescent properties of multifunctional lanthanide doped cubic KGdF4 nanocrystals.

PubMed

Yang, L W; Zhang, Y Y; Li, J J; Li, Y; Zhong, J X; Chu, Paul K

2010-12-01

Lanthanide (Ln3+) doped KGdF4 (Ln=Yb3+, Er3+, Ho3+, Tm3+) nanocrystals with a mean diameter of approximately 12 nm were synthesized by a hydrothermal method using oleic acid as a stabilizing agent at 180 °C. The nanocrystals crystallize in the cubic phase as α-NaGdF4. When excited by a 980 nm laser, these Ln3+ doped nanocrystals exhibit multicolor up-conversion (UC) emissions in red, yellow, blue and white. The calculated color coordinates demonstrate that white UC emission (CIE-X=0.352, CIE-Y=0.347) can be obtained by varying the dopant concentrations in the Yb3+/Ho3+/Tm3+ triply-doped nanocrystals to yield different RGB emission intensities. The measured field dependence of magnetization (M-H curves) of the KGdF4 nanocrystals shows their paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of Gd3+ ions. Moreover, low temperature thermal treatment can enhance UC properties, magnetization and magnetic mass susceptibility of Ln3+ doped KGdF4 nanocrystals. The multifunctional Ln3+ doped KGdF4 nanocrystals have potential applications in color displays, bioseparation, and optical-magnetic dual modal nanoprobes in biomedical imaging.

Magnetic and upconverted luminescent properties of multifunctional lanthanide doped cubic KGdF4nanocrystals

NASA Astrophysics Data System (ADS)

Yang, L. W.; Zhang, Y. Y.; Li, J. J.; Li, Y.; Zhong, J. X.; Chu, Paul K.

2010-12-01

Lanthanide (Ln3+) doped KGdF4 (Ln = Yb3+, Er3+, Ho3+, Tm3+) nanocrystals with a mean diameter of approximately 12 nm were synthesized by a hydrothermal method using oleic acid as a stabilizing agent at 180 °C. The nanocrystals crystallize in the cubic phase as α-NaGdF4. When excited by a 980 nm laser, these Ln3+ doped nanocrystals exhibit multicolor up-conversion (UC) emissions in red, yellow, blue and white. The calculated color coordinates demonstrate that white UC emission (CIE-X = 0.352, CIE-Y = 0.347) can be obtained by varying the dopant concentrations in the Yb3+/Ho3+/Tm3+ triply-doped nanocrystals to yield different RGB emission intensities. The measured field dependence of magnetization (M-H curves) of the KGdF4nanocrystals shows their paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of Gd3+ ions. Moreover, low temperature thermal treatment can enhance UC properties, magnetization and magnetic mass susceptibility of Ln3+ doped KGdF4nanocrystals. The multifunctional Ln3+ doped KGdF4nanocrystals have potential applications in color displays, bioseparation, and optical-magnetic dual modal nanoprobes in biomedical imaging.

Formation of Deep Electron Trap by Yb3+ Codoping Leads into Super-Long Persistent Luminescence in Ce3+-doped Yttrium Aluminum Gallium Garnet Phosphors.

PubMed

Ueda, Jumpei; Miyano, Shun; Tanabe, Setsuhisa

2018-05-23

The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Cr 3+ compound is one of the brightest persistent phosphors, but its persistent luminescence (PersL) duration is not so long due to the relatively shallow Cr 3+ electron trap. Comparing the vacuum referred binding energy of the electron trapping state by Cr 3+ and those by lanthanide ions, we selected Yb 3+ as a deeper electron trapping center. The Y 3 Al 2 Ga 3 O 12 :Ce 3+ -Yb 3+ phosphors show Ce 3+ :5d→4f green persistent luminescence after ceasing blue light excitation. The formation of Yb 2+ was confirmed by the increased intensity of absorption at 585 nm during the charging process. This result indicates that the Yb 3+ ions act as electron traps by capturing an electron. From the thermoluminescence glow curves, it was found the Yb 3+ trap makes much deeper electron trap with 1.01 eV depth than the Cr 3+ electron trap with 0.81 eV depth. This deeper Yb 3+ trap provides much slower detrapping rate of filled electron traps than the Cr 3+ -codoped persistent phosphor. In addition, by preparing transparent ceramics and optimizing Ce 3+ and Yb 3+ concentrations, the Y 3 Al 2 Ga 3 O 12 :Ce 3+ (0.2%)-Yb 3+ (0.1%) as-made transparent ceramic phosphor showed super long persistent luminescence for over 138.8 hours after ceasing blue light charging.

Yb7Ni4InGe12: a quaternary compound having mixed valent Yb atoms grown from indium flux.

PubMed

Subbarao, Udumula; Jana, Rajkumar; Chondroudi, Maria; Balasubramanian, Mahalingam; Kanatzidis, Mercouri G; Peter, Sebastian C

2015-03-28

The new intermetallic compound Yb7Ni4InGe12 was obtained as large silver needle shaped single crystals from reactive indium flux. Single crystal X-ray diffraction suggests that Yb7Ni4InGe12 crystallizes in the Yb7Co4InGe12 structure type, and tetragonal space group P4/m and lattice constants are a = b = 10.291(2) Å and c = 4.1460(8) Å. The crystal structure of Yb7Ni4InGe12 consists of columnar units of three different types of channels filled with the Yb atoms. The crystal structure of Yb7Ni4InGe12 is closely related to Yb5Ni4Ge10. The effective magnetic moment obtained from the magnetic susceptibility measurements in the temperature range 200-300 K is 3.66μB/Yb suggests mixed/intermediate valence behavior of ytterbium atoms. X-ray absorption near edge spectroscopy (XANES) confirms that Yb7Ni4InGe12 exhibits mixed valence.

Influence of doping on thermal diffusivity of single crystals used in photonics: measurements based on thermal wave methods.

PubMed

Bodzenta, Jerzy; Kaźmierczak-Bałata, Anna; Wokulska, Krystyna B; Kucytowski, Jacek; Łukasiewicz, Tadeusz; Hofman, Władysław

2009-03-01

Three crystals used in solid-state lasers, namely, yttrium aluminum garnet (YAG), yttrium orthovanadate (YVO(4)), and gadolinium calcium oxoborate (GdCOB), were investigated to determine the influence of dopants on their thermal diffusivity. The thermal diffusivity was measured by thermal wave method with a signal detection based on mirage effect. The YAG crystals were doped with Yb or V, the YVO(4) with Nd or Ca and Tm, and the GdCOB crystals contained Nd or Yb. In all cases, the doping caused a decrease in thermal diffusivity. The analysis of complementary measurements of ultrasound velocity changes caused by dopants leads to the conclusion that impurities create phonon scattering centers. This additional scattering reduces the phonon mean free path and accordingly results in the decrease of the thermal diffusivity of the crystal. The influence of doping on lattice parameters was investigated, additionally.

Long-Term INP Measurements within the BACCHUS project

NASA Astrophysics Data System (ADS)

Schrod, Jann; Bingemer, Heinz; Curtius, Joachim

2016-04-01

The European research project BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) studies the interactions between aerosols, clouds and the climate system, and tries to reconstruct pre-industrial aerosol and cloud conditions from data collected in pristine environments. The number concentration of Ice Nucleating Particles (INP) is an important, yet scarcely known parameter. As a partner of Work package 1 of BACCHUS we began in September 2014 to operate a globally spanned network of four INP sampling stations, which is the first of its kind. The stations are located at the ATTO observatory in the Brazilian Rainforest, the Caribbean Sea (Martinique), the Zeppelin Observatory at Svalbard in the Arctic, and in central Europe (Germany). Samples are collected routinely every day or every few days by electrostatic precipitation of aerosol particles onto Si substrates. The samples are stored in petri-slides, and shipped to our laboratory in Frankfurt, Germany. The number of ice nucleating particles on the substrate is analyzed in the isothermal static diffusion chamber FRIDGE by growing ice on the INP and photographing and counting the crystals. The measurements in the temperature range from -20°C to -30°C and relative humidities of 100-135% (with respect to ice) address primarily the deposition/condensation nucleation modes. Here we present INP and supporting aerosol data from this novel INP network for the first time.

Coupling of Ag Nanoparticle with Inverse Opal Photonic Crystals as a Novel Strategy for Upconversion Emission Enhancement of NaYF4: Yb(3+), Er(3+) Nanoparticles.

PubMed

Shao, Bo; Yang, Zhengwen; Wang, Yida; Li, Jun; Yang, Jianzhi; Qiu, Jianbei; Song, Zhiguo

2015-11-18

Rare-earth-ion-doped upconversion (UC) nanoparticles have generated considerable interest because of their potential application in solar cells, biological labeling, therapeutics, and imaging. However, the applications of UC nanoparticles were still limited because of their low emission efficiency. Photonic crystals and noble metal nanoparticles are applied extensively to enhance the UC emission of rare earth ions. In the present work, a novel substrate consisting of inverse opal photonic crystals and Ag nanoparticles was prepared by the template-assisted method, which was used to enhance the UC emission of NaYF4: Yb(3+), Er(3+) nanoparticles. The red or green UC emissions of NaYF4: Yb(3+), Er(3+) nanoparticles were selectively enhanced on the inverse opal substrates because of the Bragg reflection of the photonic band gap. Additionally, the UC emission enhancement of NaYF4: Yb(3+), Er(3+) nanoparticles induced by the coupling of metal nanoparticle plasmons and photonic crystal effects was realized on the Ag nanoparticles included in the inverse opal substrate. The present results demonstrated that coupling of Ag nanoparticle with inverse opal photonic crystals provides a useful strategy to enhance UC emission of rare-earth-ion-doped nanoparticles.

Near infrared absorbing near infrared emitting highly-sensitive luminescent nanothermometer based on Nd(3+) to Yb(3+) energy transfer.

PubMed

Marciniak, Ł; Bednarkiewicz, A; Stefanski, M; Tomala, R; Hreniak, D; Strek, W

2015-10-07

A new type of near infrared absorbing near infrared emitting (NANE) luminescent nanothermometer is presented, with a physical background that relies on efficient Nd(3+) to Yb(3+) energy transfer under 808 nm photo-excitation. The emission spectra of LiLa0.9-xNd0.1YbxP4O12 (x = 0.05, 0.1, 0.2, 0.3, 0.5) nanocrystals were measured in a wide 100-700 °C temperature range. The ratio between the Nd(3+) ((4)F3/2→(4)I9/2) and Yb(3+) ((2)F5/2→(2)F7/2) luminescence bands, and the thermometer sensitivity were found to be strongly dependent on the Yb(3+) concentration. These phenomenological relations were discussed in terms of the competition between three phenomena, namely (a) Nd(3+)→ Yb(3+) phonon assisted energy transfer, (b) Yb(3+)→ Nd(3+) back energy transfer and (c) energy diffusion between Yb(3+) ions. The highest sensitivity of the temperature measurement was found for x = 0.5 (LiLa0.4Nd0.1Yb0.5P4O12), which was equal to 4 × 10(-3) K(-1) at 330 K. In stark contrast to conventional approaches, the proposed phosphate host matrix allows for a high level of doping, and thus, owing to the negligible concentration quenching, the presented luminophores exhibit a high absorption cross section and bright emission. Moreover, such optical remote thermometers, whose excitation and emission wavelengths are weakly scattered or absorbed and fall into the optical transmission window of the skin, may therefore become a practical solution for biomedical applications, such as remote control of thermotherapy.

Synthesis and evaluation of rare-earth doped glasses and crystals for optical refrigeration

NASA Astrophysics Data System (ADS)

Patterson, Wendy

This research focused on developing and characterizing rare-earth doped, solid-state materials for laser cooling. In particular, the work targeted the optimization of the lasercooling efficiency in Yb3+ and Tm3+ doped fluorides. The first instance of laser-induced cooling in a Tm3+-doped crystal, BaY2F8 was reported. Cooling by 3 degrees Kelvin below ambient temperature was obtained in a single-pass pump geometry at lambda = 1855 nm. Protocols were developed for materials synthesis and purification which can be applied to each component of ZBLANI:Yb 3+/Tm3+ (ZrF4 -- BaF2 -- LaF3 -- AlF3 -- NaF -- InF3: YbF3/TmF3) glass to enable a material with significantly reduced transition-metal impurities. A method for OH- impurity removal and ultra-drying of the metal fluorides was also improved upon. Several characterization tools were used to quantitatively and qualitatively verify purity, including inductively-coupled plasma mass spectrometry (ICP-MS). Here we found a more than 600-fold reduction in transition-metal impurities in a ZrCl2O solution. A non-contact spectroscopic technique for the measurement of laser-induced temperature changes in solids was developed. Two-band differential luminescence thermometry (TBDLT) achieved a sensitivity of ˜7 mK and enabled precise measurement of the zero-crossing temperature and net quantum efficiency. Several Yb3+-doped ZBLANI glasses fabricated from precursors of varying purity and by different processes were analyzed in detail by TBDLT. Laser-induced cooling was observed at room temperature for several of the materials. A net quantum efficiency of 97.39+/-0.01% at 238 K was found for the best ZBLANI:1%Yb 3+ laser-cooling sample produced from purified metal-fluoride precursors, and proved competitive with the best commercially procured material. The TBDLT technique enabled rapid and sensitive benchmarking of laser-cooling materials and provided critical feedback to the development and optimization of high-performance optical

Self-propagating high-temperature synthesis and luminescent properties of ytterbium doped rare earth (Y, Sc, Lu) oxides nanopowders

NASA Astrophysics Data System (ADS)

Permin, D. A.; Novikova, A. V.; Balabanov, S. S.; Gavrishchuk, E. M.; Kurashkin, S. V.; Savikin, A. P.

2018-04-01

This paper describes a comparative study of structural and luminescent properties of 5%Yb-doped yttrium, scandium, and lutetium oxides (Yb:RE2O3) powders and ceramics fabricated by self-propagating high-temperature synthesis. According to X-ray diffractometry and electron microscopy the chosen method ensures preparation of low-agglomerated cubic Ctype crystal structured powders at one step. No crucial differences in luminescence spectra were found the Yb:RE2O3 powders and ceramics. It was shown that the emission lifetimes of the Yb:RE2O3 powders are lowered by crystal structure defects, while its values for ceramics samples are compared to that of monocrystals and more influenced by rare earth impurities.

Functional conservation of rice OsNF-YB/YC and Arabidopsis AtNF-YB/YC proteins in the regulation of flowering time.

PubMed

Hwang, Yoon-Hyung; Kim, Soon-Kap; Lee, Keh Chien; Chung, Young Soo; Lee, Jeong Hwan; Kim, Jeong-Kook

2016-04-01

Rice Os NF - YB and Os NF - YC complement the late flowering phenotype of Arabidopsis nf - yb double and nf - yc triple mutants, respectively. In addition, OsNF-YB and OsNF-YC interact with AtNF-YC and AtNF-YB, respectively. Plant NUCLEAR FACTOR Y (NF-Y) transcription factors play important roles in plant development and abiotic stress. In Arabidopsis thaliana, two NF-YB (AtNF-YB2 and AtNF-YB3) and five NF-YC (AtNF-YC1, AtNF-YC2, AtNF-YC3, AtNF-YC4, and AtNF-YC9) genes regulate photoperiodic flowering by interacting with other AtNF-Y subunit proteins. Three rice NF-YB (OsNF-YB8, OsNF-YB10, and OsNF-YB11) and five rice OsNF-YC (OsNF-YC1, OsNF-YC2, OsNF-YC4, OsNF-YC6, and OsNF-YC7) genes are clustered with two AtNF-YB and five AtNF-YC genes, respectively. To investigate the functional conservation of these NF-YB and NF-YC genes in rice and Arabidopsis, we analyzed the flowering phenotypes of transgenic plants overexpressing the respective OsNF-YB and OsNF-YC genes in Arabidopsis mutants. Overexpression of OsNF-YB8/10/11 and OsNF-YC2 complemented the late flowering phenotype of Arabidopsis nf-yb2 nf-yb3 and nf-yc3 nf-yc4 nf-yc9 mutants, respectively. The rescued phenotype of 35S::OsNF-YC2 nf-yc3 nf-yc4 nf-yc9 plants was attributed to the upregulation of FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). In vitro and in planta protein-protein analyses revealed that OsNF-YB8/10/11 and OsNF-YC1/2/4/6/7 interact with AtNF-YC3/4/9 and AtNF-YB2/3, respectively. Our data indicate that some OsNF-YB and OsNF-YC genes are functional equivalents of AtNF-YB2/3 and AtNF-YC3/4/9 genes, respectively, and suggest functional conservation of Arabidopsis and rice NF-Y genes in the control of flowering time.

Tuning upconversion luminescence of LiYF4:Yb3+,Er3+/Tm3+/Ho3+ microcrystals synthesized through a molten salt process.

PubMed

Niu, Na; He, Fei; Wang, Liuzhen; Wang, Lin; Wang, Yan; Gai, Shili; Yang, Piaoping

2014-05-01

In this paper, well-defined tetragonal-phase LiYF4:Yb3+,Er3+/Tm3+/Ho3+ micro-crystals with octahedral morphology were successfully prepared through a surfactant-free molten salt process for the first time. By gradually increasing the LiF content in the NaNO3-KNO3 reaction medium, the crystal phase transforms from a mixture of YF3 and LiYF4 to pure tetragonal-phase LiYF4. The possible formation process for the phase and morphology evolution is also presented. Moreover, upon 980 nm laser diode (LD) excitation, the lanthanide ions (Yb3+, Er3+/Tm3+/Ho3+) doped LiYF4 crystals exhibit intense upconversion emission lights. By tuning the sensitizer concentrations of Yb3+ ions in LiYF4:Yb3+,Er3+, the relative intensities of green and red emissions can be precisely adjusted under single wavelength excitation. Consequently, multicolor upconversion emissions can be obtained. On the other hand, UC mechanisms were also given based on the emission spectra and the plot of luminescence intensity to pump power.

Study of InGaAs-based modulation doped field effect transistor structures using variable-angle spectroscopic ellipsometry

NASA Technical Reports Server (NTRS)

Alterovitz, S. A.; Sieg, R. M.; Yao, H. D.; Snyder, P. G.; Woollam, J. A.; Pamulapati, J.; Bhattacharya, P. K.; Sekula-Moise, P. A.

1991-01-01

Variable-angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs-based modulation doped field effect transistor structures. Strained and unstrained InGaAs channels were made by molecular beam epitaxy (MBE) on InP substrates and by metal-organic chemical vapor deposition on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10% of the growth-calibration results. The MBE-made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice-matched concentration.

Optical transitions of Ho(3+) in oxyfluoride glasses and upconversion luminescence of Ho(3+)/Yb(3+)-codoped oxyfluoride glasses.

PubMed

Feng, Li; Wu, Yinsu

2015-05-05

Optical properties of Ho(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Ho(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980nm excitation. The effects of composition, concentration of the doping ions, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2015 Elsevier B.V. All rights reserved.

Preferentially etched epitaxial liftoff of InP material

NASA Technical Reports Server (NTRS)

Bailey, Sheila G. (Inventor); Wilt, David M. (Inventor); Deangelo, Frank L. (Inventor)

1995-01-01

The present invention is directed toward a method of removing epitaxial substrates from host substrates. A sacrificial release layer of ternary material is placed on the substrate. A layer of InP is then placed on the ternary material. Afterward a layer of wax is applied to the InP layer to apply compressive force and an etchant material is used to remove the sacrificial release layer.

Preferentially Etched Epitaxial Liftoff of InP Material

NASA Technical Reports Server (NTRS)

Bailey, Sheila G. (Inventor); Wilt, David M. (Inventor); DeAngelo, Frank L. (Inventor)

1997-01-01

The present invention is directed toward a method of removing epitaxial substrates from host substrates. A sacrificial release layer of ternary material is placed on the substrate. A layer of InP is then placed on the ternary material. Afterward a layer of wax is applied to the InP layer to apply compressive force and an etchant material is used to remove the sacrificial release layer.

Bioimaging and toxicity assessments of near-infrared upconversion luminescent NaYF4:Yb,Tm nanocrystals.

PubMed

Zhou, Jia-Cai; Yang, Zheng-Lin; Dong, Wei; Tang, Ruo-Jin; Sun, Ling-Dong; Yan, Chun-Hua

2011-12-01

In vitro or in vivo bioimaging utilizing the upconversion (UC) luminescence of rare earth fluoride nanocrystals (NCs) has attracted much attention, especially for Yb(3+)/Tm(3+) doped NCs with a near-infrared (NIR) UC emission at 800 nm. Herein, water-soluble NaYF(4):Yb,Tm NCs with strong NIR UC emission were synthesized with a solvothermal method. In vitro and in vivo bioimaging and toxicity assessments were carried out with HeLa cell and Caenorhabditis elegans (C. elegans) cases, respectively. NaYF(4):Yb,Tm NCs afforded an efficient NIR image of the HeLa cells with an incubation concentration of 10 μg mL(-1), and CCK-8 assay revealed a low cytotoxicity. Fed with Escherichia coli (E. coli) and NCs together, the C. elegans showed a NIR image in the gut from the pharynx to the anus. Further, these NCs could be excreted out when those worms were then fed with only E. coli. Toxicity studies were further addressed with protein expression, life span, egg production, egg viability, and growth rate of the worms in comparison with those of the intact ones. The feeding of rare earth fluoride NCs with a dose of 100 μg does not arise obvious toxicity effect from the growth to procreation. The in vitro and in vivo studies confirm that NaYF(4):Yb,Tm NCs could be served as an excellent NIR emission bioprobe with low toxicity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Nonepitaxial Thin-Film InP for Scalable and Efficient Photocathodes.

PubMed

Hettick, Mark; Zheng, Maxwell; Lin, Yongjing; Sutter-Fella, Carolin M; Ager, Joel W; Javey, Ali

2015-06-18

To date, some of the highest performance photocathodes of a photoelectrochemical (PEC) cell have been shown with single-crystalline p-type InP wafers, exhibiting half-cell solar-to-hydrogen conversion efficiencies of over 14%. However, the high cost of single-crystalline InP wafers may present a challenge for future large-scale industrial deployment. Analogous to solar cells, a thin-film approach could address the cost challenges by utilizing the benefits of the InP material while decreasing the use of expensive materials and processes. Here, we demonstrate this approach, using the newly developed thin-film vapor-liquid-solid (TF-VLS) nonepitaxial growth method combined with an atomic-layer deposition protection process to create thin-film InP photocathodes with large grain size and high performance, in the first reported solar device configuration generated by materials grown with this technique. Current-voltage measurements show a photocurrent (29.4 mA/cm(2)) and onset potential (630 mV) approaching single-crystalline wafers and an overall power conversion efficiency of 11.6%, making TF-VLS InP a promising photocathode for scalable and efficient solar hydrogen generation.

Comparative thermometric properties of bi-functional Er3+-Yb3+ doped rare earth (RE = Y, Gd and La) molybdates

NASA Astrophysics Data System (ADS)

Sinha, Shriya; Mahata, Manoj Kumar; Kumar, Kaushal

2018-02-01

The molybdate compounds as luminescent medium have received great attention of recent research due to their excellent intrinsic optical properties. Therefore, the investigation on the optical thermometry and nanoheating effect in Er3+-Yb3+ doped molybdates of yttrium (EYYMO), gadolinium (EYGMO) and lanthanum (EYLMO) nanophosphors is reported herein. The temperature dependent fluorescence intensity ratio of green (525 and 548 nm) emission bands of Er3+ ions were analyzed within 300-500 K temperature range to determine the thermal behavior. The comparative temperature sensitivity of the materials has been found to depend on the phonon energy of their own. The thermal sensitivity is higher in the materials with low phonon energy. The intensity ratio of the green emission bands has been found to alter with the laser excitation density, which can be used to estimate the induced temperature in the materials. Furthermore, the photothermal conversion efficiency is calculated in the water dispersed samples and the maximum photothermal conversion efficiency of 49.6% is achieved for EYGMO nanophosphor. Comparative experimental results explore unequal thermal sensing and induced optical heating in the three rare earth molybdates. The optical properties of the green emitting molybdates are interesting for temperature sensing and optical heating applications.

Four nucleocytoplasmic-shuttling proteins and p53 interact specifically with the YB-NLS and are involved in anticancer reagent-induced nuclear localization of YB-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Toru; Ohashi, Sachiyo; Kobayashi, Shunsuke

In cancer cells, anticancer reagents often trigger nuclear accumulation of YB-1, which participates in the progression of cancer malignancy. YB-1 has a non-canonical nuclear localization signal (YB-NLS). Here we found that four nucleocytoplasmic-shuttling RNA-binding proteins and p53 interact specifically with the YB-NLS and co-accumulate with YB-1 in the nucleus of actinomycin D-treated cells. To elucidate the roles of these YB-NLS-binding proteins, we performed a dominant-negative experiment in which a large excess of YB-NLS interacts with the YB-NLS-binding proteins, and showed inhibitory effects on actinomycin D-induced nuclear transport of endogenous YB-1 and subsequent MDR1 gene expression. Furthermore, the YB-NLS-expressing cells weremore » also found to show increased drug sensitivity. Our results suggest that these YB-NLS-associating proteins are key factors for nuclear translocation/accumulation of YB-1 in cancer cells. - Highlights: • Four nucleocytoplasmic-shuttling proteins and p53 associate with YB-NLS. • They showed nuclear co-accumulation with YB-1 in actinomycin D-treated cells. • Overexpression of YB-NLS was carried out to take YB-NLS-binding proteins from YB-1. • YB-NLS inhibited actinomycin D-induced nuclear localization of endogenous YB-1. • YB-NLS suppressed actinomycin D-induced expression of MDR1.« less

Electrochemical characterization of p(+)n and n(+)p diffused InP structures

NASA Technical Reports Server (NTRS)

Wilt, David M.; Faur, Maria; Faur, Mircea; Goradia, M.; Vargas-Aburto, Carlos

1993-01-01

The relatively well documented and widely used electrolytes for characterization and processing of Si and GaAs-related materials and structures by electrochemical methods are of little or no use with InP because the electrolytes presently used either dissolve the surface preferentially at the defect areas or form residual oxides and introduce a large density of surface states. Using an electrolyte which was newly developed for anodic dissolution of InP, and was named the 'FAP' electrolyte, accurate characterization of InP related structures including nature and density of surface states, defect density, and net majority carrier concentration, all as functions of depth was performed. A step-by-step optimization of n(+)p and p(+)n InP structures made by thermal diffusion was done using the electrochemical techniques, and resulted in high performance homojunction InP structures.

Quantum sized Ag nanocluster assisted fluorescence enhancement in Tm{sup 3+}-Yb{sup 3+} doped optical fiber beyond plasmonics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chattopadhyay, Rik; Haldar, Arindam; Paul, Mukul C.

2015-12-07

We report a process for enhancing fluorescence emission from conventional rare earth ions in optical fiber by metal nanocluster (MNC) in nonresonant indirect pumping. The process is completely different from formal metal enhanced fluorescence phenomenon as the MNCs are too small in size to support localized surface plasmon and the excitation wavelength is far from plasmon resonance frequency. We used an established theory of two coupled oscillators to explain the simultaneous enhancement of Ytterbium (Yb{sup 3+}) and Thulium (Tm{sup 3+}) emission by silver (Ag) NCs under nonresonant pumping in optical fiber. The fiber is pumped with a 980 nm fiber pigtailedmore » laser diode with input power of 20–100 mW to excite the Yb{sup 3+}. Four times enhancement of Yb{sup 3+} emission of 900–1100 nm and Tm{sup 3+} upconversion emission around 474 nm, 650 nm, and 790 nm is observed in the fiber with Ag NCs.« less

Plasma Deposited SiO2 for Planar Self-Aligned Gate Metal-Insulator-Semiconductor Field Effect Transistors on Semi-Insulating InP

NASA Technical Reports Server (NTRS)

Tabory, Charles N.; Young, Paul G.; Smith, Edwyn D.; Alterovitz, Samuel A.

1994-01-01

Metal-insulator-semiconductor (MIS) field effect transistors were fabricated on InP substrates using a planar self-aligned gate process. A 700-1000 A gate insulator of Si02 doped with phosphorus was deposited by a direct plasma enhanced chemical vapor deposition at 400 mTorr, 275 C, 5 W, and power density of 8.5 MW/sq cm. High frequency capacitance-voltage measurements were taken on MIS capacitors which have been subjected to a 700 C anneal and an interface state density of lxl0(exp 11)/eV/cq cm was found. Current-voltage measurements of the capacitors show a breakdown voltage of 107 V/cm and a insulator resistivity of 10(exp 14) omega cm. Transistors were fabricated on semi-insulating InP using a standard planar self-aligned gate process in which the gate insulator was subjected to an ion implantation activation anneal of 700 C. MIS field effect transistors gave a maximum extrinsic transconductance of 23 mS/mm for a gate length of 3 microns. The drain current drift saturated at 87.5% of the initial current, while reaching to within 1% of the saturated value after only 1x10(exp 3). This is the first reported viable planar InP self-aligned gate transistor process reported to date.

The down-conversion and up-conversion photoluminescence properties of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}:Yb{sup 3+}/Pr{sup 3+} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Yinpeng; Luo, Laihui, E-mail: luolaihui@nbu.edu.cn; Wang, Jia

2015-07-28

Na{sub 0.5}Bi{sub 0.5−x−y}Yb{sub x}Pr{sub y}TiO{sub 3} (NBT:xYb/yPr) ceramics with different Yb and Pr contents are prepared. Both the down-conversion (DC) and up-conversion (UC) photoluminescence (PL) of the ceramics via 453 and 980 nm excitation, respectively, are investigated. The effect of Yb{sup 3+} and Pr{sup 3+} doping contents on the DC and UC PL is significantly different from each other. Furthermore, the UC PL of the ceramics as a function of temperatures is measured to investigate the UC process in detail. Based on energy level diagram of Pr{sup 3+} and Yb{sup 3+} ions and the DC and UC PL spectra, the DCmore » and UC PL mechanisms of Pr{sup 3+} and Yb{sup 3+} ions are discussed. Especially, the UC PL mechanism is clarified, which is different from the previously reported literature. Also, the temperature sensing properties of the ceramics are studied based on the photoluminescence ratio technique, using the thermal coupling energy levels of Pr{sup 3+}.« less

High-temperature thermoelectric properties of Ca0.92La0.04RE0.04MnO3 (RE = Sm, Dy and Yb) prepared by coprecipitation

NASA Astrophysics Data System (ADS)

Li, Cuiqin; Chen, Qianlin; Yan, Yunan; Li, Yanan; Zhao, Ying

2018-02-01

A series of Ca0.92La0.04RE0.04MnO3 (RE = Sm, Dy and Yb) compounds are synthesized via a coprecipitation technique. The influence of La/RE dual doping on the phase structure, microstructure and thermoelectric properties of the CaMnO3 system is investigated. Increased material density with grain sizes of 1-2 μm and a homogeneous microstructure is realized. Dual doping decreases the electrical resistivity due to an increase in the carrier concentration and also decreases the thermal conductivity due to increased grain scattering, damping of local vibrations by heavier La/RE ions compared to Ca and lattice distortion. The Ca0.92La0.04Yb0.04MnO3 shows the highest power factor of 3.49 × 10-4 W m-1 K-2 and the highest dimensionless figure of merit ZT of 0.25 at 770 K, which is approximately 3 times larger than that obtained for the undoped CaMnO3 and significantly larger than that of single-doped CaMnO3 prepared by solid-state reaction. This work provides a basic foundation for the industrial application of this thermoelectric material.

Wafer-scale self-organized InP nanopillars with controlled orientation for photovoltaic devices.

PubMed

Sanatinia, Reza; Berrier, Audrey; Dhaka, Veer; Perros, Alexander P; Huhtio, Teppo; Lipsanen, Harri; Anand, Srinivasan

2015-10-16

A unique wafer-scale self-organization process for generation of InP nanopillars is demonstrated, which is based on maskless ion-beam etching (IBE) of InP developed to obtain the nanopillars, where the height, shape, and orientation of the nanopillars can be varied by controlling the processing parameters. The fabricated InP nanopillars exhibit broadband suppression of the reflectance, 'black InP,' a property useful for solar cells. The realization of a conformal p-n junction for carrier collection, in the fabricated solar cells, is achieved by a metalorganic vapor phase epitaxy (MOVPE) overgrowth step on the fabricated pillars. The conformal overgrowth retains the broadband anti-reflection property of the InP nanopillars, indicating the feasibility of this technology for solar cells. Surface passivation of the formed InP nanopillars using sulfur-oleylamine solution resulted in improved solar-cell characteristics. An open-circuit voltage of 0.71 V and an increase of 0.13 V compared to the unpassivated device were achieved.

Fluorescence investigation of Ho3+ in Yb3+ sensitized mixed-alkali bismuth gallate glasses.

PubMed

Lin, H; Zhang, Y Y; Pun, E Y B

2008-12-15

Efficient 2.0 microm infrared and visible upconversion emissions have been observed in Ho3+/Yb3+ co-doped mixed-alkali bismuth gallate (LKBBG) glasses having a maximum-phonon energy of 673 cm(-1). The Judd-Ofelt parameters Omega2, Omega4 and Omega6 of Ho3+ indicate that there is a high asymmetry and strong covalent environment in LKBBG glasses. The large absorption and emission cross-sections of Yb3+ confirm that it is a suitable sensitizer for capturing and transferring pump energy to Ho3+. The emission cross-section profile for the 5I7-->5I8 transition is derived using the reciprocity method and the peak value is 5.54 x 10(-21)cm2, which is much larger than the value in fluorozircoaluminate glasses. LKBBG glasses exhibit low maximum-phonon energy and large refractive index, and it is possible to achieve an effective 1.66 microm U-band emission of Ho3+ under 900 nm laser radiation.

Cathodoluminescence of InP

NASA Technical Reports Server (NTRS)

Gatos, C. H.; Vaughan, J. J.; Lagowski, J.; Gatos, H. C.

1981-01-01

Cathodoluminescence studies were carried out on p-type InP having carrier concentrations ranging from 7.2 x 10 to the 16th to 7.4 x 10 to the 18th per cu cm in the temperature range of 80-580 K. It was found that low-temperature spectra exhibited peaks at 1.41 and 1.38 eV. These peaks were attributed to band-to-band and band-acceptor transitions, respectively. The dependence of the band-to-band peak on temperature was used to extend knowledge of the temperature dependence of the energy gap of InP to 550 K. It was shown that the half-width of the cathodoluminescence peak can be used for the determination of carrier concentration and carrier-concentration inhomogeneities in the material. The variations of the cathodoluminescence peak height with temperature indicated the possibility of Auger recombination for high carrier concentrations (7.4 x 10 to the 18th per cu cm) at temperatures above 450 K.

Efficient up-conversion in Yb:Er:NaT(XO4)2 thermal nanoprobes. Imaging of their distribution in a perfused mouse

PubMed Central

Serrano, María Dolores; Han, Xiumei; Cascales, Concepción; Cantero, Marta; Montoliu, Lluís; Arza, Elvira; Caiolfa, Valeria R.; Zamai, Moreno

2017-01-01

Yb and Er codoped NaT(XO4)2 (T = Y, La, Gd, Lu and X = Mo, W) disordered oxides show a green (Er3+ related) up-conversion (UC) efficiency comparable to that of Yb:Er:β-NaYF4 compound and unless 3 times larger UC ratiometric thermal sensitivity. The similar UC efficiency of Yb:Er doped NaT(XO4)2 and β-NaYF4 compounds allowed testing equal subcutaneous depths of ex-vivo chicken tissue in both cases. This extraordinary behavior for NaT(XO4)2 oxides with large cutoff phonon energy (ħω≈ 920 cm-1) is ascribed to 4F9/2 electron population recycling to higher energy 4G11/2 level by a phonon assisted transition. Crystalline nanoparticles of Yb:Er:NaLu(MoO4)2 have been synthesized by sol-gel with sizes most commonly in the 50–80 nm range, showing a relatively small reduction of the UC efficiency with regards to bulk materials. Fluorescence lifetime and multiphoton imaging microscopies show that these nanoparticles can be efficiently distributed to all body organs of a perfused mouse. PMID:28542327

Carrier thermalization dynamics in single zincblende and wurtzite InP Nanowires.

PubMed

Wang, Yuda; Jackson, Howard E; Smith, Leigh M; Burgess, Tim; Paiman, Suriati; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati

2014-12-10

Using transient Rayleigh scattering (TRS) measurements, we obtain photoexcited carrier thermalization dynamics for both zincblende (ZB) and wurtzite (WZ) InP single nanowires (NW) with picosecond resolution. A phenomenological fitting model based on direct band-to-band transition theory is developed to extract the electron-hole-plasma density and temperature as a function of time from TRS measurements of single nanowires, which have complex valence band structures. We find that the thermalization dynamics of hot carriers depends strongly on material (GaAs NW vs InP NW) and less strongly on crystal structure (ZB vs WZ). The thermalization dynamics of ZB and WZ InP NWs are similar. But a comparison of the thermalization dynamics in ZB and WZ InP NWs with ZB GaAs NWs reveals more than an order of magnitude slower relaxation for the InP NWs. We interpret these results as reflecting their distinctive phonon band structures that lead to different hot phonon effects. Knowledge of hot carrier thermalization dynamics is an essential component for effective incorporation of nanowire materials into electronic devices.

Wide bandgap, strain-balanced quantum well tunnel junctions on InP substrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lumb, M. P.; US Naval Research Laboratory, Washington, DC 20375; Yakes, M. K.

In this work, the electrical performance of strain-balanced quantum well tunnel junctions with varying designs is presented. Strain-balanced quantum well tunnel junctions comprising compressively strained InAlAs wells and tensile-strained InAlAs barriers were grown on InP substrates using solid-source molecular beam epitaxy. The use of InAlAs enables InP-based tunnel junction devices to be produced using wide bandgap layers, enabling high electrical performance with low absorption. The impact of well and barrier thickness on the electrical performance was investigated, in addition to the impact of Si and Be doping concentration. Finally, the impact of an InGaAs quantum well at the junction interfacemore » is presented, enabling a peak tunnel current density of 47.6 A/cm{sup 2} to be realized.« less

Observation of defect-assisted enhanced visible whispering gallery modes in ytterbium-doped ZnO microsphere

NASA Astrophysics Data System (ADS)

Khanum, Rizwana; Moirangthem, Rakesh S.; Das, Nayan Mani

2017-06-01

Smooth surfaced and crystalline undoped and ytterbium doped zinc oxide (ZnO) microspheres having an approximate size of 3-5 μm were synthesized by hydrothermal process. Out of these microspheres, a single microparticle was chosen and engaged as a whispering gallery wave microresonator. The defect induced luminescence from an individual ZnO microsphere was investigated with micro-photoluminescence measurement in the spectral range of 565 to 740 nm under the excitation of a green laser having a centered wavelength at 532 nm. The defects-related emissions from a single ZnO microsphere show optical resonance peaks so-called "whispering gallery modes" (WGMs) which are confirmed with the theoretical calculation. Further, ZnO microspheres were chemically doped with the different molar percentages of Ytterbium (Yb), and enhancement in their emission properties was investigated. Our experimental results show that ZnO microspheres with 0.5 mol. % doping of Yb gives the strongest optical emission and has highest Q-factor which can be employed in the development of WGM based optical biosensor or laser.

Ultralow surface recombination velocity in InP nanowires probed by terahertz spectroscopy.

PubMed

Joyce, Hannah J; Wong-Leung, Jennifer; Yong, Chaw-Keong; Docherty, Callum J; Paiman, Suriati; Gao, Qiang; Tan, H Hoe; Jagadish, Chennupati; Lloyd-Hughes, James; Herz, Laura M; Johnston, Michael B

2012-10-10

Using transient terahertz photoconductivity measurements, we have made noncontact, room temperature measurements of the ultrafast charge carrier dynamics in InP nanowires. InP nanowires exhibited a very long photoconductivity lifetime of over 1 ns, and carrier lifetimes were remarkably insensitive to surface states despite the large nanowire surface area-to-volume ratio. An exceptionally low surface recombination velocity (170 cm/s) was recorded at room temperature. These results suggest that InP nanowires are prime candidates for optoelectronic devices, particularly photovoltaic devices, without the need for surface passivation. We found that the carrier mobility is not limited by nanowire diameter but is strongly limited by the presence of planar crystallographic defects such as stacking faults in these predominantly wurtzite nanowires. These findings show the great potential of very narrow InP nanowires for electronic devices but indicate that improvements in the crystallographic uniformity of InP nanowires will be critical for future nanowire device engineering.

Comparison on different repetition rate locking methods in Er-doped fiber laser

NASA Astrophysics Data System (ADS)

Yang, Kangwen; Zhao, Peng; Luo, Jiang; Huang, Kun; Hao, Qiang; Zeng, Heping

2018-05-01

We demonstrate a systematic comparative research on the all-optical, mechanical and opto-mechanical repetition rate control methods in an Er-doped fiber laser. A piece of Yb-doped fiber, a piezoelectric transducer and an electronic polarization controller are simultaneously added in the laser cavity as different cavity length modulators. By measuring the cavity length tuning ranges, the output power fluctuations, the temporal and frequency repetition rate stability, we show that all-optical method introduces the minimal disturbances under current experimental condition.

Radiation effects in heteroepitaxial InP solar cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Curtis, H. B.; Swartz, C. K.; Brinker, D. J.; Vargas-Aburto, C.

1993-01-01

Heteroepitaxial InP solar cells, with GaAs substrates, were irradiated by 0.5 and 3 MeV protons and their performance, temperature dependency, and carrier removal rates determined as a function of fluence. The radiation resistance of the present cells was significantly greater than that of non-heteroepitaxial InP cells at both proton energies. A clear difference in the temperature dependency of V(sub oc), was observed between heteroepitaxial and homoepitaxial InP cells. The analytically predicted dependence of dV(sub oc)/dT on Voc was confirmed by the fluence dependence of these quantities. Carrier removal was observed to increase with decreasing proton energy. The results obtained for performance and temperature dependency were attributed to the high dislocation densities present in the heteroepitaxial cells while the energy dependence of carrier removal was attributed to the energy dependence of proton range.

Different growth regimes in InP nanowire growth mediated by Ag nanoparticles.

PubMed

Oliveira, D S; Zavarize, M; Tizei, L H G; Walls, M; Ospina, C A; Iikawa, F; Ugarte, D; Cotta, M A

2017-12-15

We report on the existence of two different regimes in one-step Ag-seeded InP nanowire growth. The vapor-liquid-solid-mechanism is present at larger In precursor flows and temperatures, ∼500 °C, yielding high aspect ratio and pure wurtzite InP nanowires with a semi-spherical metal particle at the thin apex. Periodic diameter oscillations can be achieved under extreme In supersaturations at this temperature range, showing the presence of a liquid catalyst. However, under lower temperatures and In precursor flows, large diameter InP nanowires with mixed wurtzite/zincblende segments are obtained, similarly to In-assisted growth. Chemical composition analysis suggest that In-rich droplet formation is catalyzed at the substrate surface via Ag nanoparticles; this process might be facilitated by the sulfur contamination detected in these nanoparticles. Furthermore, part of the original Ag nanoparticle remains solid and is embedded inside the actual catalyst, providing an in situ method to switch growth mechanisms upon changing In precursor flow. Nevertheless, our Ag-seeded InP nanowires exhibit overall optical emission spectra consistent with the observed structural properties and similar to Au-catalyzed InP nanowires. We thus show that Ag nanoparticles may be a suitable replacement for Au in InP nanowire growth.

Nd- And Er-Doped Phosphate Glass For Fiber Laser.

NASA Astrophysics Data System (ADS)

Yamashita, Toshiharu T.

1990-02-01

Laser fibers prepared from Nd- and Er-doped phosphate glass possessing a large stimulated emission cross section have been investigated both in a single fiber and in a fiber bundle. In the single fiber, continuous wave oscillations were successfully obtained at 1.054 p.m and 1.366 µm on a high Nd-doped single-mode fiber of 10 mm in length and also at 1.535 pm in a Er-doped single-mode fiber, sensitized by Nd, Yb. Especially, a low threshold of 1 mw and a high slope-efficiency of 50% were achieved in 1.054 pm laser oscillation on a Nd-doped fiber, end-pumped with a laser diode. A fiber bundle of phosphate glass doped with 8 wt% Nd2O3 yielded an average output power of 100 W at 50 pps where the bundle was 4.6 mm in diameter and was side-pumped with flash lamps.

Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling.

PubMed

Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

2016-09-23

InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

Tunable absorption resonances in the ultraviolet for InP nanowire arrays.

PubMed

Aghaeipour, Mahtab; Anttu, Nicklas; Nylund, Gustav; Samuelson, Lars; Lehmann, Sebastian; Pistol, Mats-Erik

2014-11-17

The ability to tune the photon absorptance spectrum is an attracting way of tailoring the response of devices like photodetectors and solar cells. Here, we measure the reflectance spectra of InP substrates patterned with arrays of vertically standing InP nanowires. Using the reflectance spectra, we calculate and analyze the corresponding absorptance spectra of the nanowires. We show that we can tune absorption resonances for the nanowire arrays into the ultraviolet by decreasing the diameter of the nanowires. When we compare our measurements with electromagnetic modeling, we generally find good agreement. Interestingly, the remaining differences between modeled and measured spectra are attributed to a crystal-phase dependence in the refractive index of InP. Specifically, we find indication of significant differences in the refractive index between the modeled zinc-blende InP nanowires and the measured wurtzite InP nanowires in the ultraviolet. We believe that such crystal-phase dependent differences in the refractive index affect the possibility to excite optical resonances in the large wavelength range of 345 < λ < 390 nm. To support this claim, we investigated how resonances in nanostructures can be shifted in wavelength by geometrical tuning. We find that dispersion in the refractive index can dominate over geometrical tuning and stop the possibility for such shifting. Our results open the door for using crystal-phase engineering to optimize the absorption in InP nanowire-based solar cells and photodetectors.

Anisotropic strain relaxation of Si-doped metamorphic InAlAs graded buffers on InP

NASA Astrophysics Data System (ADS)

Gu, Yi; Zhang, Yonggang; Chen, Xingyou; Ma, Yingjie; Zheng, Yuanliao; Du, Ben; Zhang, Jian

2017-09-01

The effects of Si doping on the strain relaxation of InP-based metamorphic In x Al1-x As graded buffers have been investigated. The highly Si-doped sample shows an increased ridge period along the [1 1 0] direction in the cross-hatch morphology measured by atomic force microscope. X-ray diffraction reciprocal space mapping measurements reveal that the high Si-doping induced incomplete relaxation as well as inhomogeneous residual strain along the [1 -1 0] direction, which was also observed in micro-Raman measurements. The anisotropic strain relaxation is attributed to the Si-doping enhanced anisotropy of misfit dislocations along the orthogonal directions. The α-misfit dislocations along the [1 -1 0] direction are further delayed to generate in highly Si-doped InAlAs buffer, while the β-misfit dislocations along the [1 1 0] direction are not. These results supply useful suggestions on the design and demonstration of semiconductor metamorphic devices.

Spectroscopy and visible frequency upconversion in Er3+-Yb3+: TeO2-ZnO glass.

PubMed

Mohanty, Deepak Kumar; Rai, Vineet Kumar

2014-01-01

The UV-Vis-NIR absorption studies of the Er(3+)/Er(3+)-Yb(3+) doped/codoped TeO2-ZnO (TZO) glasses fabricated by the melting and quenching method has been performed. The spectroscopic radiative parameters viz. radiative transition probabilities, branching ratios and lifetimes have been determined from the absorption spectrum by using Judd-Ofelt theory. The near infrared (NIR) to visible frequency upconversion (UC) have been monitored by using an excitation of 976 nm wavelength radiation from a CW diode laser. The effect of codoping with Yb(3+) ions on the intensity of the UC emission bands from the Er(3+) ions throughout visible region has been studied. The mechanism responsible for the observed upconversion emissions in the prepared samples have been explained on the basis of excited state absorption and efficient energy transfer processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Size and shape effects in β-NaGdF4: Yb3+, Er3+ nanocrystals

NASA Astrophysics Data System (ADS)

Noculak, Agnieszka; Podhorodecki, Artur

2017-04-01

Three sets of β-NaGdF4:Yb3+, Er3+ nanocrystals (NCs) with different shapes (spherical and more complex flower shapes), different sizes (6-17 nm) and Yb3+ concentrations (2%-15%) were synthesized by a co-precipitation method using oleic acid as a stabilizing agent. The uncommon, single-crystalline flower-shaped NCs were obtained by simply adjusting the fluorine-to-lanthanides molar ratio. Additionally, some of the NCs with different sizes have been covered by the un-doped shell. The crystal phase, shapes and sizes of all NCs were examined using transmission electron microscopy and x-ray diffraction methods. Simultaneously, upconversion luminescence and lifetimes, under 980 nm excitation, were measured and the changes in green to red (G/R) emission ratios as well as emission decay times were correlated with the evolution of nanocrystal sizes and surface to volume ratios. Three different mechanisms responsible for the changes in G/R ratios were presented and discussed.

Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm(3+) and Yb(3+).

PubMed

Soares, M R N; Ferro, M; Costa, F M; Monteiro, T

2015-12-21

Lanthanide doped inorganic nanoparticles with upconversion luminescence are of utmost importance for biomedical applications, solid state lighting and photovoltaics. In this work we studied the downshifted luminescence, upconversion luminescence (UCL) and blackbody radiation of tetragonal yttrium stabilized zirconia co-doped with Tm(3+) and Yb(3+) single crystals and nanoparticles produced by laser floating zone and laser ablation in liquids, respectively. The photoluminescence (PL) and PL excitation (PLE) were investigated at room temperature (RT). PL spectra exhibit the characteristic lines in UV, blue/green, red and NIR regions of the Tm(3+) (4f(12)) under resonant excitation into the high energy (2S+1)LJ multiplets. Under NIR excitation (980 nm), the samples placed in air display an intense NIR at ∼800 nm due to the (1)G4→(3)H5/(3)H4→(3)H6 transitions. Additionally, red, blue/green and ultraviolet UCL is observed arising from higher excited (1)G4 and (1)D2 multiplets. The power excitation dependence of the UCL intensity indicated that 2-3 low energy absorbed photons are involved in the UCL for low power levels, while for high powers, the identified saturation is dependent on the material size with a enhanced effect on the NPs. The temperature dependence of the UCL was investigated for single crystals and targets used in the ablation. An overall increase of the integrated intensity was found to occur between 12 K and the RT. The thermally activated process is described by activation energies of 10 meV and 30 meV for single crystals and targets, respectively. For the NPs, the UCL was found to be strongly sensitive to pressure conditions. Under vacuum conditions, instead of the narrow lines of the Tm(3+), a wide blackbody radiation was detected, responsible for the change in the emission colour from blue to orange. This phenomenon is totally reversible when the NPs are placed at ambient pressure. The UCL/blackbody radiation in the nanosized material exhibits

Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

DOEpatents

Krupke, William F.; Payne, Stephen A.; Marshall, Christopher D.

2001-01-01

The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

Multicolor tuning towards single red-emission band of upconversion nanoparticles for tunable optical component and optical/x-ray imaging agents via Ce(3+) doping.

PubMed

Yi, Zhigao; Zeng, Tianmei; Xu, Yaru; Lu, Wei; Qian, Chao; Liu, Hongrong; Zeng, Songjun; Hao, Jianhua

2015-09-25

A simple strategy of Ce(3+) doping is proposed to realize multicolor tuning and predominant red emission in BaLnF5:Yb(3+)/Ho(3+) (Ln(3+) = Gd(3+), Y(3+), Yb(3+)) systems. A tunable upconversion (UC) multicolor output from green/yellow to red can be readily achieved in a fixed Yb(3+)/Ho(3+) composition by doping Ce(3+), providing an effective route for multicolor tuning widely used for various optical components. Moreover, compared with Ce(3+)-free UC nanoparticles (UCNPs), a remarkable enhancement of the red-to-green (R/G) ratio is observed by doping 30% Ce(3+), arising from the two largely promoted cross-relaxation (CR) processes between Ce(3+) and Ho(3+). UCNPs with pure red emission are selected as in vivo UC bioimaging agents, demonstrating the merits of deep penetration depth, the absence of autofluorescence and high contrast in small animal bioimaging. Moreover, such fluorescence imaging nanoprobes can also be used as contrast agents for three-dimensional (3D) x-ray bioimaging by taking advantage of the high K-edge values and x-ray absorption coefficients of Ba(2+), Gd(3+), and Ce(3+) in our designed nanoprobes. Thus, the simultaneous realization of multicolor output, highly enhanced R/G ratio, and predominant red emission makes the Ce(3+)-doped UCNPs very useful for widespread applications in optical components and bioimaging.

Fiber Amplifier Report for NEPP 2008

NASA Technical Reports Server (NTRS)

Thomes, Joe; Ott, Melanie; LaRocca, Frank; Chuska, Rick; Switzer, Rob

2008-01-01

Ongoing qualification activities of LiNbO3 modulators. Passive (unpumped) radiation testing of Er-, Yb-, and Er/Yb-doped fibers: a) Yb-doped fibers exhibit higher radiation resistance than Er-doped fibers; b) Er/Yb co-doped fibers exhibit largest radiation resistance. Active (pumped) radiation testing of Yb-doped fibers conducted at NASA GSFC: a) Typical decay behavior observed; b) No comparison could be made to other fibers due to problems with test setup. Development of new high power fiber terminations.

InP Heterojunction Bipolar Transistor Amplifiers to 255 GHz

NASA Technical Reports Server (NTRS)

Radisic, Vesna; Sawdai, Donald; Scott, Dennis; Deal, William; Dang, Linh; Li, Danny; Cavus, Abdullah; To, Richard; Lai, Richard

2009-01-01

Two single-stage InP heterojunction bipolar transistor (HBT) amplifiers operate at 184 and 255 GHz, using Northrop Grumman Corporation s InP HBT MMIC (monolithic microwave integrated circuit) technology. At the time of this reporting, these are reported to be the highest HBT amplifiers ever created. The purpose of the amplifier design is to evaluate the technology capability for high-frequency designs and verify the model for future development work.

Tuning from green to red the upconversion emission of Y2O3:Er3+-Yb3+ nanophosphors

NASA Astrophysics Data System (ADS)

Diaz-Torres, L. A.; Salas, P.; Oliva, J.; Resendiz-L, E.; Rodriguez-Gonzalez, C.; Meza, O.

2017-01-01

In this work, the structural, morphological and luminescent properties of Y2O3 nanophosphors doped with Er3+ (1 mol%) and different Yb3+ concentrations (2-12 mol%) have been studied. Those nanophosphors were synthesized using a simple hydrothermal method. XRD analysis indicates that all the samples presented a pure cubic phase even for Yb concentrations as high as 12 mol%. In addition, SEM images show nanoparticles with quasi-spherical shapes with average sizes in the range of 300-340 nm. Photoluminescence measurements obtained after excitation at 967 nm revealed that our samples have strong green (563 nm) and red emissions (660 nm) corresponding to 2H11/2 + 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3+ ions, respectively. We also observed that the green band is quenched and the red emission enhanced as the Yb concentration increases. In consequence, the CIE coordinates changed from (0.35, 0.64) in the green region to (0.59, 0.39) in the red region. Thus, the tuning properties of Y2O3 nanophosphors suggest that they are good candidates for applications in lighting.

Ytterbium-doped glass-ceramics for optical refrigeration.

PubMed

Filho, Elton Soares de Lima; Krishnaiah, Kummara Venkata; Ledemi, Yannick; Yu, Ye-Jin; Messaddeq, Younes; Nemova, Galina; Kashyap, Raman

2015-02-23

We report for the first time the characterization of glass-ceramics for optical refrigeration. Ytterbium-doped nanocrystallites were grown in an oxyfluoride glass matrix of composition 2YbF(3):30SiO(2)-15Al(2)O(3)-25CdF(2)-22PbF(2)-4YF(3), forming bulk glass-ceramics at three different crystalisation levels. The samples are compared with a corresponding uncrystalised (glass) sample, as well as a Yb:YAG sample which has presented optical cooling. The measured X-ray diffraction spectra, and thermal capacities of the samples are reported. We also report for the first time the use of Yb:YAG as a reference for absolute photometric quantum efficiency measurement, and use the same setup to characterize the glass and glass-ceramic samples. The cooling figure-of-merit was measured by optical calorimetry using a fiber Bragg grating and found to depend on the level of crystallization of the sample, and that samples with nanocrystallites result in higher quantum efficiency and lower background absorption than the pure-glass sample. In addition to laser-induced cooling, the glass-ceramics have the potential to serve as a reference for quantum efficiency measurements.

Hydrogen Passivation of Interstitial Zn Defects in Heteroepitaxial InP Cell Structures and Influence on Device Characteristics

NASA Technical Reports Server (NTRS)

Ringel, S. A.; Chatterjee, B.

2004-01-01

Hydrogen passivation of heteroepitaxial InP solar cells is of recent interest for deactivation of dislocations and other defects caused by the cell/substrate lattice mismatch that currently limit the photovoltaic performance of these devices. In this paper we present strong evidence that, in addition to direct hydrogen-dislocation interactions, hydrogen forms complexes with the high concentration of interstitial Zn defects present within the p(+) Zn-doped emitter of MOCVD-grown heteroepitaxial InP devices, resulting in a dramatic increase of the forward bias turn-on voltage by as much as 280 mV, from 680 mV to 960 mV. This shift is reproducible and thermally reversible and no such effect is observed for either n(+)p structures or homoepitaxial p(+)n structures grown under identical conditions. A combination of photoluminescence (PL), electrochemical C-V dopant profiling, SIMS and I-V measurements were performed on a set of samples having undergone a matrix of hydrogenation and post-hydrogenation annealing conditions to investigate the source of this voltage enhancement and confirm the expected role of interstitial Zn and hydrogen. A precise correlation between all measurements is demonstrated which indicates that Zn interstitials within the p(+) emitter and their interaction with hydrogen are indeed responsible for this device behavior.

Modeling transient gain dynamics in a cladding-pumped Yb-doped fiber ampliefier pulsed at low repetition rates

NASA Technical Reports Server (NTRS)

Valley, G. C.; Wright, M.

2001-01-01

Simulations of 1-50 kHz repetition rate, pulsed Yb-fiber amplifiers show peak powers to 10 kW with half-widths < 30 ns, consistent with commercial amplifier performance. This device is a potential source for deep space-communication.

Limits to Maximum Absorption Length in Waveguide Photodiodes

DTIC Science & Technology

2011-04-13

InGaAsP to InGaAs graded layer (35 nm), a very thin undoped InGaAs absorber layer (20 nm), a p- InP cla~din~ layer (1 J.Lm, Zn = 1x1018 em·\\ a p- InP ...expected excess opticall_oss results from non-ideal coupling, excess waveguide scattering, Zn diffusion from the p-doped InP , larger than...waveguide scattering, Zn diffusion from the p-doped InP , n-doped region absorption, or a combination of the above. The SCOWPD has demonst:r:ated an

A near-infrared luminescent Mn2+-doped NaYF4:Yb,Tm/Fe3+ upconversion nanoparticles redox reaction system for the detection of GSH/Cys/AA.

PubMed

Zhang, Liping; Ling, Bo; Wang, Lun; Chen, Hongqi

2017-09-01

An upconversion luminescence method was developed for the determination of glutathione (GSH), L-cysteine (Cys) or L-ascorbic acid (AA) based on redox reaction. We synthesized poly(acrylic acid) (PAA)-modified Mn 2+ -doped NaYF 4 :Yb,Tm upconversion nanoparticles (UCNPs), and the luminescence of these UCNPs was effectively quenched due to their carboxyl groups coordinating with Fe 3+ to form a UCNPs/Fe 3+ system. GSH, Cys or AA reduced Fe 3+ to Fe 2+ , which induced the luminescence recovery of the UCNPs. Under the optimized conditions, wide linear concentration ranges from 0.25-300μM for GSH, 0.5-875μM for Cys and 0.5-350μM for AA were found, and the detection limits (3S/K) were 0.2μM, 0.5μM and 0.2μM, respectively. Thus, the UCNPs/Fe 3+ system was successfully applied for sensing GSH, Cys or AA. Copyright © 2017 Elsevier B.V. All rights reserved.

An improved large signal model of InP HEMTs

NASA Astrophysics Data System (ADS)

Li, Tianhao; Li, Wenjun; Liu, Jun

2018-05-01

An improved large signal model for InP HEMTs is proposed in this paper. The channel current and charge model equations are constructed based on the Angelov model equations. Both the equations for channel current and gate charge models were all continuous and high order drivable, and the proposed gate charge model satisfied the charge conservation. For the strong leakage induced barrier reduction effect of InP HEMTs, the Angelov current model equations are improved. The channel current model could fit DC performance of devices. A 2 × 25 μm × 70 nm InP HEMT device is used to demonstrate the extraction and validation of the model, in which the model has predicted the DC I–V, C–V and bias related S parameters accurately. Project supported by the National Natural Science Foundation of China (No. 61331006).

Workshop on Heteroepitaxial InP Solar Cells

NASA Technical Reports Server (NTRS)

Weinberg, I.; Walters, R. W.

1993-01-01

In a generic sense, the justification for any sort of InP solar cell research applies, i.e. to take advantage of the inherently high radiation resistance and efficiency of InP solar cells. To be more specific, the approach is justified by its potential for significant cost reduction and the availability of greatly increased cell area afforded by substrates such as Si and Ge. The use of substrates, such as the latter two, would result in increased ruggedness, ease of handling, and improved manufacturability. The use of more rugged substrates would lead to a greatly increased capability for cell thinning leading to the desirable feature of reduced array weight.

Yb:Lu2SiO5 crystal : characterization of the laser emission along the three dielectric axes

NASA Astrophysics Data System (ADS)

Toci, Guido; Pirri, Angela; Beitlerova, Alena; Shoji, Yasuhiro; Yoshikawa, Akira; Hybler, Jiri; Nikl, Martin; Vannini, Matteo

2015-05-01

Yb:doped Lu2SiO5 (Lutetium orthosilicate, LSO) is an optically biaxial crystal with laser emission in the range 1000- 1100 nm. It features different absorption and emission spectra for polarization along its three dielectric axes. In this work we have characterized the laser emission properties of Yb:LSO along all the three dielectric axis, evidencing differences that can be exploited in the design of ultrafast laser sources. The material was tested in a longitudinally pumped laser cavity. The laser emission efficiency was found similar along all the three dielectric axes, with slope efficiencies around 90% in most cases. Regarding the tuning range, for the most favourable polarization direction we obtained a continuously tunable emission between 993 and 1088 nm (i. e. 95 nm) peaked at 1040 nm. The tuning curves along the three dielectric axes spanned similar ranges but with relevant differences in the shape.

Wurtzite-Phased InP Micropillars Grown on Silicon with Low Surface Recombination Velocity.

PubMed

Li, Kun; Ng, Kar Wei; Tran, Thai-Truong D; Sun, Hao; Lu, Fanglu; Chang-Hasnain, Connie J

2015-11-11

The direct growth of III-V nanostructures on silicon has shown great promise in the integration of optoelectronics with silicon-based technologies. Our previous work showed that scaling up nanostructures to microsize while maintaining high quality heterogeneous integration opens a pathway toward a complete photonic integrated circuit and high-efficiency cost-effective solar cells. In this paper, we present a thorough material study of novel metastable InP micropillars monolithically grown on silicon, focusing on two enabling aspects of this technology-the stress relaxation mechanism at the heterogeneous interface and the microstructure surface quality. Aberration-corrected transmission electron microscopy studies show that InP grows directly on silicon without any amorphous layer in between. A set of periodic dislocations was found at the heterointerface, relaxing the 8% lattice mismatch between InP and Si. Single crystalline InP therefore can grow on top of the fully relaxed template, yielding high-quality micropillars with diameters expanding beyond 1 μm. An interesting power-dependence trend of carrier recombination lifetimes was captured for these InP micropillars at room temperature, for the first time for micro/nanostructures. By simply combining internal quantum efficiency with carrier lifetime, we revealed the recombination dynamics of nonradiative and radiative portions separately. A very low surface recombination velocity of 1.1 × 10(3) cm/sec was obtained. In addition, we experimentally estimated the radiative recombination B coefficient of 2.0 × 10(-10) cm(3)/sec for pure wurtzite-phased InP. These values are comparable with those obtained from InP bulk. Exceeding the limits of conventional nanowires, our InP micropillars combine the strengths of both nanostructures and bulk materials and will provide an avenue in heterogeneous integration of III-V semiconductor materials onto silicon platforms.

Oxidation of InP nanowires: a first principles molecular dynamics study.

PubMed

Berwanger, Mailing; Schoenhalz, Aline L; Dos Santos, Cláudia L; Piquini, Paulo

2016-11-16

InP nanowires are candidates for optoelectronic applications, and as protective capping layers of III-V core-shell nanowires. Their surfaces are oxidized under ambient conditions which affects the nanowire physical properties. The majority of theoretical studies of InP nanowires, however, do not take into account the oxide layer at their surfaces. In this work we use first principles molecular dynamics electronic structure calculations to study the first steps in the oxidation process of a non-saturated InP nanowire surface as well as the properties of an already oxidized surface of an InP nanowire. Our calculations show that the O 2 molecules dissociate through several mechanisms, resulting in incorporation of O atoms into the surface layers. The results confirm the experimental observation that the oxidized layers become amorphous but the non-oxidized core layers remain crystalline. Oxygen related bonds at the oxidized layers introduce defective levels at the band gap region, with greater contributions from defects involving In-O and P-O bonds.

A high-coverage nanoparticle monolayer for the fabrication of a subwavelength structure on InP substrates.

PubMed

Kim, Dae-Seon; Park, Min-Su; Jang, Jae-Hyung

2011-08-01

Subwavelength structures (SWSs) were fabricated on the Indium Phosphide (InP) substrate by utilizing the confined convective self-assembly (CCSA) method followed by reactive ion etching (RIE). The surface condition of the InP substrate was changed by depositing a 30-nm-thick SiO2 layer and subsequently treating the surface with O2 plasma to achieve better surface coverage. The surface coverage of nanoparticle monolayer reached 90% by using O2 plasma-treated SiO2/InP substrate among three kinds of starting substrates such as the bare InP, SiO2/InP and O2 plasma-treated SiO2/InP substrate. A nanoparticle monolayer consisting of polystyrene spheres with diameter of 300 nm was used as an etch mask for transferring a two-dimensional periodic pattern onto the InP substrate. The fabricated conical SWS with an aspect ratio of 1.25 on the O2 plasma-treated SiO2/InP substrate exhibited the lowest reflectance. The average reflectance of the conical SWS was 5.84% in a spectral range between 200 and 900 nm under the normal incident angle.

InP electroluminescence as a tool to directly monitor carrier leakage in InGaAsP/InP buried heterostructure lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stern, M.B.; Brody, E.; Sowell, B.

1987-12-15

Direct measurements of homojunction and heterojunction carrier leakage currents in InGaAsP/InP buried heterostructure lasers have been made by monitoring the electroluminescence (EL) at 0.96 ..mu..m in the InP confinement layers. These EL measurements show directly, for the first time, a correlation between homojunction leakage currents and the sublinearity in the 1.3-..mu..m light output-current characteristic. The observed decrease in the 0.96-..mu..m intensity with increasing p-dopant concentration is a direct confirmation that heterojunction leakage is reduced when the doping level in the p-InP confinement layer is increased.

A comparative study of performance parameters of n(+)-p InP solar cells made by closed-ampoule sulfur diffusion into Cd- and Zn-doped p-type InP substrates

NASA Technical Reports Server (NTRS)

Faur, Mircea; Faur, Maria; Goradia, Chandra; Goradia, Manju; Thomas, Ralph D.; Brinker, David J.; Fatemi, Navid S.; Honecy, Frank S.

1991-01-01

Preliminary results indicate that Cd-doped substrates are better candidates for achieving high efficiency solar cells fabricated by closed-ampoule sulfur (S) diffusion than Zn-doped substrates. The differences in performance parameters (i.e., 14.3 percent efficiency for Cd-doped vs. 11.83 percent in the case of Zn-doped substrates of comparable doping and etch pit densities) were explained in terms of a large increase in dislocation density as a result of S diffusion in the case of Zn-doped as compared to Cd-doped substrates. The In(x)S(y) and probably Zn(S) precipitates in the case of Zn-doped substrates, produce a dead layer which extends deep below the surface and strongly affects the performance parameters. It should be noted that the cells had an unoptimized single layer antireflective coating of SiO, a grid shadowing of 6.25 percent, and somewhat poor contacts, all contributing to a reduction in efficiency. It is believed that by reducing the external losses and further improvement in cell design, efficiencies approaching 17 percent at 1 AMO, 25 degrees should be possible for cells fabricated on these relatively high defect density Cd-doped substrates. Even higher efficiencies, 18 to 19 percent should be possible by using long-lifetime substrates and further improving front surface passivation. If solar cells fabricated on Cd-doped substrates turn out to have comparable radiation tolerance as those reported in the case of cells fabricated on Zn-doped substrates, then for certain space missions 18 to 19 percent efficient cells made by this method of fabrication would be viable.

White light upconversion emission in Yb3+/ Er3+/ Tm3+ codoped oxy-fluoride lithium tungsten tellurite glass ceramics

NASA Astrophysics Data System (ADS)

Ansari, Ghizal F.; Mahajan, S. K.

2012-02-01

The bright white upconversion emission ( tri-colour UC) is generated in Er/Tm/Yb tri -doped oxy-fluoride lithium tungsten tellurite (TWLOF)glass ceramics containing crystalline phase LiYbF4 under the excitation of 980nm laser diode. The most appropriate combination of rare-earth ions (2mol% YbF3 1mol% ErF3 and 1mol%TmF3 )of glass ceramic sample has been determined to tune the primary colour (RGB and generate white light emission. By varying the pump power, intense and weak blue (487nm, 437nm), green (525nm and 545nm) and red (662nm) emission are simultaneously observed at room temperature. The dependence of upconversion emission intensity suggest that a theephoton process is responsible for the blue emission of Tm3+ ions and red emission due to both Tm3+ and Er3+ ions , while green emission originated from two photon processes in Er3+ ions. Also tri colour upconvesion and energy transfer in this glass ceramics sample were studied under 808nm laser diode excitation. The Upconversion mechanisms and Tm3+ ions plays role of both emitter and activator (transfer energy to Er) were discussed.

Nd3+/Yb3+ cascade-sensitized single-band red upconversion emission in active-core/active-shell nanocrystals.

PubMed

Ding, M Y; Hou, J J; Yuan, Y J; Bai, W F; Lu, C H; Xi, J H; Ji, Z G; Chen, D Q

2018-08-24

Lanthanide-doped upconversion nanomaterials (UCNMs) have promoted extensive interest for its biological research and biomedical applications, benefiting from low autofluorescence background, deep light penetration depth, and minimal photo-damage to biological tissues. However, owing to the 980 nm laser-induced overheating issue and the attenuation effect associated with conventional multi-peak emissions, the usage of UCNMs as fluorescent bioprobes is still limited. To address these issues, an effective strategy has been proposed to tune both the excitation and emission peaks of UCNMs into the first biological window (650 ∼ 900 nm), where the light absorption by water and hemoglobin in biological tissues is minimal. Based on the Nd 3+ /Yb 3+ cascade-sensitized upconversion process and efficient exchange-energy transfer between Mn 2+ and Er 3+ in conjunction with the active-core@active-shell nanostructured design, we have developed a new class of upconversion nanoparticles (UCNPs) that exhibit strong single-band red emission upon excitation of an 808 nm near-infrared laser. Hopefully, the well-designed KMnF 3 :Yb/Er/Nd@ KMnF 3 :Yb/Nd core-shell nanocrystals will be considered a promising alternative to conventionally used UCNPs for biolabeling applications without the concern of the overheating issue and the attenuation constraints.

Voc Degradation in TF-VLS Grown InP Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Yubo; Sun, Xingshu; Johnston, Steve

2016-11-21

Here we consider two hypotheses to explain the open-circuit voltage (VOC) degradation observed in thin-film vapor-liquid-solid (TF-VLS) grown p-type InP photovoltaic cells: bandgap narrowing and local shunting. First, a bandgap (Eg) narrowing effect is hypothesized, based on the surface inhomogeneity of VLS InP captured by the photoluminescence (PL) image. The PL data was used to estimate a spatially-resolved active VOC across surface of the InP sample. Combining this data with the effective Jsc allowed an assessment of the I-V characteristics of individual unit cells. Next, an H-SPICE diode compact model was utilized to reproduce the I-V characteristics of the wholemore » sample. We find a good fit to the I-V performance of TF-VLS grown InP solar cell. Second, a local shunting effect was also considered as an alternative explanation of the VOC degradation effect. Again, PL image data was used, and small local shunt resistance was added in arbitrary elementary unit cells to represent certain dark spots seen in the PL image and dictate the VOC degradation occurred in the sample.« less

Effect of defect state on photon synergistic process in KLu2F7:Yb3+, Er3+ nanoparticles

NASA Astrophysics Data System (ADS)

Bian, Wenjuan; Lu, Wei; Qi, Yushuang; Yu, Xue; Zhou, Dacheng; Yang, Yong; Qiu, Jianbei; Xu, Xuhui

2016-10-01

The synergistic effect appeared due to the cooperative dual-wavelength excitation by near-infrared (NIR) and ultraviolet (UV) light in rare-earth doped nano-particles (NPs) is very important to improve solar cell efficiency. Herein, we studied the synergistic effect combined with the energy levels of Er3+ ions and the defect states in KLu2F7 NPs. The introduction of Ce3+ ions in KLu2F7:16%Yb3+, 2%Er3+ NPs results in significant improvement of synergistic effect by producing more vacancy defects (VK‧) which serves as shallow traps. We verify unambiguously that the control of the defects distribution exerts a facile approach to promote the synergistic effect with the assistance of Ce3+ ions doping.

Mode-locked ytterbium-doped fiber laser based on topological insulator: Bi₂Se₃.

PubMed

Dou, Zhiyuan; Song, Yanrong; Tian, Jinrong; Liu, Jinghui; Yu, Zhenhua; Fang, Xiaohui

2014-10-06

We demonstrated an all-normal-dispersion Yb-doped mode-locked fiber laser based on Bi₂Se₃ topological insulator (TI). Different from previous TI-mode-locked fiber lasers in which TIs were mixed with film-forming agent, we used a special way to paste a well-proportioned pure TI on a fiber end-facet. In this way, the effect of the film-forming agent could be removed, thus the heat deposition was relieved and damage threshold could be improved. The modulation depth of the Bi₂Se₃ film was measured to be 5.2%. When we used the Bi₂Se₃ film in the Yb-doped fiber laser, the mode locked pulses with pulse energy of 0.756 nJ, pulse width of 46 ps and the repetition rate of 44.6 MHz were obtained. The maximum average output power was 33.7 mW. When the pump power exceeded 270 mW, the laser can operate in multiple pulse state that six-pulse regime can be realized. This contribution indicates that Bi₂Se₃ has an attractive optoelectronic property at 1μm waveband.

Scalable InP integrated wavelength selector based on binary search.

PubMed

Calabretta, Nicola; Stabile, Ripalta; Albores-Mejia, Aaron; Williams, Kevin A; Dorren, Harm J S

2011-10-01

We present an InP monolithically integrated wavelength selector that implements a binary search for selecting one from N modulated wavelengths. The InP chip requires only log(2)N optical filters and log(2)N optical switches. Experimental results show nanosecond reconfiguration and error-free wavelength selection of four modulated wavelengths with 2 dB of power penalty. © 2011 Optical Society of America

Spectroscopy and enhanced frequency upconversion in Nd3+-Yb3+ codoped TPO glasses: energy transfer and NIR to visible upconverter.

PubMed

Azam, Mohd; Rai, Vineet Kumar; Mohanty, Deepak Kumar

2017-09-22

TeO 2 -Pb 3 O 4 (TPO) glasses codoped with Nd 3+ and Yb 3+ ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ∼3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd 3+ doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd 3+ ions. The radiative transition probability for the 4 G 7/2  →  4 I 9/2 transition (∼1926 Hz) is found to be maximum compared to other 4 G 5/2  →  4 I 9/2 (∼1622 Hz) and 4 F 5/2  →  4 I 9/2 (∼865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb 3+ ions in the Nd 3+ doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ∼17, ∼12 and ∼42 times as compared to that of the Nd 3+ singly doped glass. The quantum efficiency for the 4 G 7/2 level is found to be ∼32%. The nephelauxetic ratio, bonding parameter and covalency of Nd 3+ ions have been found positive which represents the covalent bonding between Nd 3+ ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Spectroscopy and enhanced frequency upconversion in Nd3+-Yb3+ codoped TPO glasses: energy transfer and NIR to visible upconverter

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar; Mohanty, Deepak Kumar

2017-09-01

TeO2-Pb3O4 (TPO) glasses codoped with Nd3+ and Yb3+ ions have been fabricated by conventional melting technique. The absorption, emission and excitation spectra of the samples have been recorded. The optical band gap in both the doped/codoped glasses is found to be ˜3.31 eV. Judd-Ofelt analysis has been carried out by using the absorption spectrum of 0.8 mol% Nd3+ doped glass to determine the radiative properties viz radiative transition probabilities, branching ratios, radiative lifetimes, quality factor and emission cross sections of some emitting levels for Nd3+ ions. The radiative transition probability for the 4G7/2 → 4I9/2 transition (˜1926 Hz) is found to be maximum compared to other 4G5/2 → 4I9/2 (˜1622 Hz) and 4F5/2 → 4I9/2 (˜865 Hz) transitions. Upconversion (UC) luminescence of the samples has been examined by the 980 nm CW diode laser excitation. Effect of addition of Yb3+ ions in the Nd3+ doped glasses on UC emission intensity has been discussed. The UC emission intensity corresponding to the green, red and NIR bands in the codoped glass has been enhanced by ˜17, ˜12 and ˜42 times as compared to that of the Nd3+ singly doped glass. The quantum efficiency for the 4G7/2 level is found to be ˜32%. The nephelauxetic ratio, bonding parameter and covalency of Nd3+ ions have been found positive which represents the covalent bonding between Nd3+ ion and oxygen atom. The colour tunability from yellowish-green to dominant green region has been obtained in the optimized codoped TPO glass.

Enhanced light output from the nano-patterned InP semiconductor substrate through the nanoporous alumina mask.

PubMed

Jung, Mi; Kim, Jae Hun; Lee, Seok; Jang, Byung Jin; Lee, Woo Young; Oh, Yoo-Mi; Park, Sun-Woo; Woo, Deokha

2012-07-01

A significant enhancement in the light output from nano-patterned InP substrate covered with a nanoporous alumina mask was observed. A uniform nanohole array on an InP semiconductor substrate was fabricated by inductively coupled plasma reactive ion etching (ICP-RIE), using the nanoporous alumina mask as a shadow mask. The light output property of the semiconductor substrate was investigated via photoluminescence (PL) intensity measurement. The InP substrate with a nanohole array showed a more enhanced PL intensity compared with the raw InP substrate without a nanohole structure. After ICP-RIE etching, the light output from the nanoporous InP substrate covered with a nanoporous alumina mask showed fourfold enhanced PL intensity compared with the raw InP substrate. These results can be used as a prospective method for increasing the light output efficiency of optoelectronic devices.

Analysis of tellurium as n-type dopant in GaInP: Doping, diffusion, memory effect and surfactant properties

NASA Astrophysics Data System (ADS)

García, I.; Rey-Stolle, I.; Galiana, B.; Algora, C.

2007-01-01

The use of tellurium as n-type dopant for GaAs and InP has several advantages, including a high incorporation efficiency, the very high doping levels achievable and a low diffusion coefficient. However, its use to dope Ga xIn 1-xP is not straightforward, since it shows several problems like a remarkable memory effect and an acute inertia of the material to become Te-doped, which gives rise to gradual doping profiles. In this paper, all these phenomena are studied and quantified using secondary ion mass spectroscopy (SIMS) and electrochemical CV profiling (ECV) measurements. Concerning the gradual doping profiles, their origin is linked to the interaction of Te and In in the gas phase and on the growth surface. A phenomenological explanation is given for this effect although the exact physical processes behind remain to be defined.

Enhanced persistent red luminescence in Mn2+-doped (Mg,Zn)GeO3 by electron trap and conduction band engineering

NASA Astrophysics Data System (ADS)

Katayama, Yumiko; Kayumi, Tomohiro; Ueda, Jumpei; Tanabe, Setsuhisa

2018-05-01

The effect of Zn substitution on the persistent luminescence properties of MgGeO3:Mn2+-Ln3+ (Ln = Eu and Yb) red phosphors was investigated. The intensity of the persistent luminescence of the Eu3+ co-doped phosphors increased with increasing Zn content, whereas that of the Yb3+ co-doped samples decreased. For both series of lanthanide co-doped samples, the thermoluminescence (TL) glow peak shifted to the lower temperature side with increasing Zn content. These persistent luminescence properties were well explained in terms of lowering of the bottom of the conduction band relative to the ground state of the divalent lanthanide ions. Especially, in Eu3+ co-doped system, TL peak shifted from 520 K to 318 K by 50% Zn substitution. The persistent radiance of the (Mg0.5 Zn0.5)GeO3: Mn2+-Eu3+ sample at 1 h after ceasing UV light was 46 times stronger than that of MgGeO3:Mn2+-Eu3+, and 11 times stronger than that of ZnGa2O4: Cr3+ standard deep red persistent phosphor.

Transport, Thermal, and Magnetic Properties of YbNi3X9 (X = Al, Ga): A Newly Synthesized Yb-Based Kondo Lattice System

NASA Astrophysics Data System (ADS)

Yamashita, Tetsuro; Miyazaki, Ryoichi; Aoki, Yuji; Ohara, Shigeo

2012-03-01

We have succeeded in synthesizing a new Yb-based Kondo lattice system, YbNi3X9 (X = Al, Ga). Our study reveals that YbNi3Al9 shows typical features of a heavy-fermion antiferromagnet with a Néel temperature of TN = 3.4 K. All of the properties reflect a competition between the Kondo effect and the crystalline electric field (CEF) effect. The moderate heavy-fermion state leads to an enhanced Sommerfeld coefficient of 100 mJ/(mol\\cdotK2), even if ordered antiferromagnetically. On the other hand, the isostructural gallide YbNi3Ga9 is an intermediate-valence system with a Kondo temperature of TK = 570 K. A large hybridization scale can overcome the CEF splitting energy, and a moderately heavy Fermi-liquid ground state with high local moment degeneracy should form at low temperatures. Note that the quality of single-crystalline YbNi3X9 is extremely high compared with those of other Yb-based Kondo lattice compounds. We conclude that YbNi3X9 is a suitable system for investigating the electronic structure of Yb-based Kondo lattice systems from a heavy-fermion system with an antiferromagnetically ordered ground state to an intermediate-valence system.

Comparative modeling of InP solar cell structures

NASA Technical Reports Server (NTRS)

Jain, R. K.; Weinberg, I.; Flood, D. J.

1991-01-01

The comparative modeling of p(+)n and n(+)p indium phosphide solar cell structures is studied using a numerical program PC-1D. The optimal design study has predicted that the p(+)n structure offers improved cell efficiencies as compared to n(+)p structure, due to higher open-circuit voltage. The various cell material and process parameters to achieve the maximum cell efficiencies are reported. The effect of some of the cell parameters on InP cell I-V characteristics was studied. The available radiation resistance data on n(+)p and p(+)p InP solar cells are also critically discussed.

Probing the Crystal Structure and Formation Mechanism of Lanthanide-Doped Upconverting Nanocrystals

DOE PAGES

Hudry, Damien; Abeykoon, A. M. M.; Dooryhee, E.; ...

2016-11-23

Lanthanide (Ln)-doped upconverting nanocrystals (UCNCs), such as NaLnF 4 (with Ln = lanthanide), constitute an important class of nanoscale materials due to their capacity to convert near-infrared photons into near-ultraviolet or visible light. Although under intense investigation for more than a decade, UCNCs have been relatively underexplored especially regarding their crystal structure and mechanisms of formation in organic media. The former is needed to explain the relationship between atomic scale structure and upconversion (UC) properties of UCNCs (i.e., local symmetry for 4f–4f transition probability, Ln 3+ distances for energy migration), while the latter is essential to finely tune the size, morphology, chemical composition, and architecture of well-defined upconverting nanostructures, which constitute the experimental levers to modify the optical properties. In this contribution, we use synchrotron-based diffraction experiments coupled to Rietveld and pair distribution function (PDF) analyses to understand the formation of NaGdF 4:Yb:Er UCNCs in organic media and to investigate their crystal structure. Our results reveal a complex mechanism of the formation of NaGdF 4:Yb:Er UCNCs based on chemical reactions involving molecular clusters and in situ-generated, crystalline sodium fluoride at high temperature. Additionally, a detailed crystallographic investigation of NaGdF 4:Yb:Er UCNCs is presented. Our Rietveld and PDF analyses show that the space group Pmore » $$\\bar{6}$$ is the one that best describes the crystal structure of NaGdF 4:Yb:Er UCNCs contrary to what has been recently proposed. Further, our Rietveld and PDF data reveal the formation of bulk-like crystal structure down to 10 nm with limited distortions. Finally, the results presented in this paper constitute an important step toward the comprehensive understanding of the underlying picture that governs UC properties of lanthanide-doped nanostructures.« less

Robust upward dispersion of the neutron spin resonance in the heavy fermion superconductor Ce 1–xYb xCoIn 5

DOE PAGES

Song, Yu; Van Dyke, John; Lum, I. K.; ...

2016-09-28

Here, the neutron spin resonance is a collective magnetic excitation that appears in copper oxide, iron pnictide, and heavy fermion unconventional superconductors. Although the resonance is commonly associated with a spin-exciton due to the d(s ±)-wave symmetry of the superconducting order parameter, it has also been proposed to be a magnon-like excitation appearing in the superconducting state. Here we use inelastic neutron scattering to demonstrate that the resonance in the heavy fermion superconductor Ce 1–xYb xCoIn 5 with x=0,0.05,0.3 has a ring-like upward dispersion that is robust against Yb-doping. By comparing our experimental data with random phase approximation calculation usingmore » the electronic structure and the momentum dependence of the d x2 –y2-wave superconducting gap determined from scanning tunneling microscopy for CeCoIn 5, we conclude the robust upward dispersing resonance mode in Ce 1–xYb xCoIn 5 is inconsistent with the downward dispersion predicted within the spin-exciton scenari« less

Photoluminescence of transparent glass-ceramics based on ZnO nanocrystals and co-doped with Eu3+, Yb3+ ions

NASA Astrophysics Data System (ADS)

Arzumanyan, Grigory M.; Kuznetsov, Evgeny A.; Zhilin, Aleksandr A.; Dymshits, Olga S.; Shemchuk, Daria V.; Alekseeva, Irina P.; Mudryi, Alexandr V.; Zhivulko, Vadim D.; Borodavchenko, Olga M.

2016-12-01

Glasses of the K2Osbnd ZnOsbnd Al2O3sbnd SiO2 system co-doped with Eu2O3 and Yb2O3 were prepared by the melt-quenching technique. Transparent zincite (ZnO) glass-ceramics were obtained by secondary heat-treatments at 680-860 °C. At 860 °C, traces of Eu oxyapatite appeared in addition to ZnO nanocrystals. The average crystal size obtained from the X-ray diffraction data was found to range between 14 and 35 nm. Absorption spectra of the initial glasses are composed of an absorption edge and absorption bands due to electronic transitions of Eu3+ ions. With heat-treatment, the absorption edge pronouncedly shifts to the visible spectral range. The luminescence properties of the glass and glass-ceramics were studied by measuring their excitation and emission spectra at 300, 78, and 4.2 K. Strong red emission of Eu3+ ions dominated by the 5D0-7F2 (612 nm) electric dipole transition was detected. Changes in the luminescence properties of the Eu3+-related excitation and emission bands were observed after heat-treatments at 680 °C and 860 °C. The ZnO nanocrystals showed both broad luminescence (400-850 nm) and free-exciton emission near 3.3 eV at room temperature. The upconversion luminescence spectrum of the initial glass was obtained under excitation of the 976 nm laser source.

Optical transitions of Tm3+ in oxyfluoride glasses and compositional and thermal effect on upconversion luminescence of Tm3+/Yb3+-codoped oxyfluoride glasses.

PubMed

Feng, Li; Wu, Yinsu; Liu, Zhuo; Guo, Tao

2014-01-24

Optical properties of Tm(3+)-doped SiO2-BaF2-ZnF2 glasses have been investigated on the basis of the Judd-Ofelt theory. Judd-Ofelt intensity parameters, radiative transition probabilities, fluorescence branching ratios and radiative lifetimes have been calculated for different glass compositions. Upconversion emissions were observed in Tm(3+)/Yb(3+)-codoped SiO2-BaF2-ZnF2 glasses under 980 nm excitation. The effects of composition, concentration of the doping ions, temperature, and excitation pump power on the upconversion emissions were also systematically studied. Copyright © 2013 Elsevier B.V. All rights reserved.

Photoluminescence study of as-grown vertically standing wurtzite InP nanowire ensembles.