Abstract

Up-conversion luminescence processes of Tb3+ ions in GeO2-Ga2O3-BaO glass system were investigated under diode-laser excitation of Yb3+. Emission bands at 489, 543, 586 and 621nm corresponding to 5D47FJ (J = 6, 5, 4, 3) transitions and luminescence at 381, 415, 435 nm resulting from 5D3, 5G67FJ (J = 6, 5, 4) transitions of Tb3+ were observed. The highest up-conversion emission intensity was obtained for 0.7Yb2O3/0.7Tb2O3 co-doped lead-free germanate glass. The energy transfer coefficient was determined based on fitting of calculations and experimental results by least squares method. The energy transfer coefficient amounts to Cf = 1.5∙10−33 cm6/s while quantum efficiency of the Yb3+→Tb3+ energy transfer is 12%.

© 2014 Optical Society of America

1. Introduction

Optical glasses and glass fibers doped with lanthanide ions, emitting radiation in the visible range by means of frequency up-conversion, have found numerous practical applications [1,2]. Universal demand for compact glass fiber sources and amplifiers necessitates the pursuit for brand new glass materials containing lanthanide elements. Incorporation of Tb3+ and Yb3+ ions to various host matrices is important in relation to applications in modern optics. Two quite different excited state relaxation processes can be observed for Yb3+/Tb3+ doubly doped systems, i. e. down-conversion and up-conversion. In the down-conversion luminescence processes, Tb3+(5D4) → 2Yb3+(2F5/2), two infrared photons are emitted for each Tb3+ ion de-excited by the energy transfer to two Yb3+ ions. These phenomena, so called quantum-cutting effects, have been analysed for different optical systems [35]. The quantum cutting material placed on the front surface of a conventional silicon solar cell is able to split a high-energy photon into two near-infrared (NIR) photon that match the energy gap of silicon (1.12 eV), and therefore enhance the conversion efficiency of silicon solar cells [6]. The second relaxation deals with up-conversion luminescence. Green emission due to main 5D47F5 transition of Tb3+ is successfully detected under near-infrared excitation of Yb3+ by 976 nm diode laser line. The up-conversion luminescence processes were examined for Yb3+/Tb3+ ions in single crystals [7], glasses [8] and glass fibers [9] as well as glass-ceramics containing fluoride nanocrystals [10,11]. A special attention has been paid to inorganic glasses containing Tb3+ and Yb3+ ions. Cooperative energy transfer between Tb3+ and Yb3+ ions occurs in tellurites [12], fluorophosphates [13] borates [14] as well as silica based glasses prepared by conventional high-temperature melting technique [15] and low-temperature sol-gel methods [16], but not specifically in lead-free germanate glasses. Spectroscopic properties of Yb3+/Tb3+ ions in oxyfluoride lead germanate glasses, glass fibers and glass-ceramics were examined in details [17,18]. Germanate-based glasses, owing to their good capacity for dissolving lanthanides [19,20] and relatively low phonon energies (850 cm−1) enable to effective conversion of IR to VIS. It is derived from the fact that high concentration of RE ions (donor and acceptor) ensure efficient optical pump absorption, energy transfer and in result emission from acceptor ion. Therefore, germanate glasses are an attractive alternative for tellurite and heavy metal glasses. Moreover, glass fibers can be quite easily formed from precursor germanate glasses, which is important from the optical [21] and medical [22] point of view. Lanthanide-doped germanate glasses were studied for fiber lighting in minimally invasive surgery [2325]. Generally, spectroscopic properties of germanate glass fibers singly [26] or doubly [27] doped with lanthanide ions are well documented in literature. Their favorable material properties and high stability make it possible to form them into fiber-optic structures.

In this work, the effects of optical pumping by NIR diode-laser and cooperative energy transfer processes between Yb3+ and Tb3+ in germanate glass are presented. The results of the conducted research into optimization of Yb3+/Tb3+ dopants concentration in a glass from GeO2-Ga2O3-BaO system, ultimately aiming at maximization of up-conversion emission intensity, are discussed. The Yb3+→Tb3+ energy transfer efficiency is analyzed, along with the energy transfer coefficient Cf determination by means of the fitting method. To the best of our knowledge, cooperative energy transfer processes were not examined for lead-free germanate glasses containing Yb3+ and Tb3+ ions.

2. Experimental

Glasses with (1-y)50GeO2-25GaO-10BaO-15Na2O-0.7Yb2O3-yTb2O3, (y = 0.07, 0.15, 0.35, 0.7, 1.0) composition (in mol%) were melted from spectrally pure (99,99%) raw materials. The homogenized set was placed in a platinum crucible and melted in an electric furnace in T = 1500°C for 30 minutes. The molten glass was poured out onto a brass plate and then exposed to the process of annealing in air atmosphere at 610°C for 12 h to remove thermal strains. The glass samples were cutted and polished in order to carry out the optical measurements. Finally, a series of samples with the dimensions of 6x6x2mm3 were prepared. Emission spectra were measured at a station equipped with a Stellarnet Green-wave spectrometer and a pumping LIMO32-F200-DL980-LM laser diode (λp = 976 nm) with an optical fiber output having the maximum optical power P = 30W. A system PTI QuantaMaster QM40 coupled with tunable pulsed optical parametric oscillator (OPO), pumped by a third harmonic of a Nd:YAG laser (Opotek Opolette 355 LD) was used for luminescence decay measurements. The laser system was equipped with a double 200 mm monochromator, a multimode UV-VIS PMT (R928) and Hamamatsu H10330B-75 detectors controlled by a computer. Luminescence decay curves were recorded and stored by a PTI ASOC-10 [USB-2500] oscilloscope with an accuracy of ± 1 µs. The procedure of energy transfer coefficient determination was based on fitting of calculations and experimental results by least squares method. The calculated values were optimized by minimizing (simplex method) the sum of the squares o deviations of the calculated results, from experimental ones. The quality of the fits was characterized by the root-mean-squares deviation (RMS).

3. Results and discussion

Figure 1 presents emission spectra of Tb3+ ions in germanate glasses under excitation of Yb3+ by diode laser with λp = 976 nm, Ppump = 2W. Inset shows the logarithmic dependence of emission intensity on pumping radiation power. All possible transitions are schematized on the energy level diagram of Tb3+ and Yb3+ ions in germanate glass (Fig. 2).

 

Fig. 1 Emission spectra for Yb3+/Tb3+ co-doped germanate glasses. Inset shows dependence of upconversion emission intensity of 0.7Yb3+/0.7Tb3+ co-doped germanate glass on excitation power (λp = 976 nm).

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Fig. 2 Simplified energy level diagram of Tb3+/Yb3+ ion and possible upconversion luminescence mechanisms.

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The up-conversion spectra consist of seven emission bands related to 5D47FJ (J = 6, 5, 4, 3) and 5D3,(5G6)→7FJ (J = 6, 5, 4) transitions of Tb3+. Terbium ions do not absorb directly the 976 nm pumping radiation. Instead, they become excited in the course of cooperative energy transfer from Yb3+ ions. As for the excited state 5D4, it is populated in the course of cooperative energy transfer between a pair of excited Yb3+ and a neighboring Tb3+ by 2-photon process.

2×Yb3+(2F5/2)+Tb3+(7F6)2×Yb3+(2F7/2)+Tb3+(5D4)
Furthermore, three emission bands with several times lower emission intensity were recorded at 381, 415, and 435 nm, which correspond to 5D3,(5G6)→7FJ (J = 6, 5, 4) transitions, respectively. The 5D3, 5G6 level is populated by 3-photon process according to the following pattern: a portion of Tb3+ ions excited in effect of cooperative energy transfer to 5D4 level absorb a photon of 976 nm pumping radiation (ESA), and transferred to 5D1 level. Simultaneously, the second route of energy transfer is constituted by an excited Yb3+ ion (2F5/2). In the next step, fast 5D15D3 non-radiative relaxation takes place. The whole process can be described by the following mechanism:
Tb3+(5D4)+Yb3+(2F5/2)+hνrelaxation,Tb3+(5D3)        
The logarithmic dependence of up-conversion intensity on pumping radiation power confirms this hypothesis. The slopes for emission bands at 381, 415, 435 nm are close to 2.39, 2.50 and 2.25, indicating a three-photon up-conversion mechanism. Difference in slope values is less than 10%. Similar behavior was observed in lanthanum borogermanate and lanthanum - aluminum - germanate glasses [6,28]. By the same way, the slopes for bands at 489, 543, 586 and 621 nm have values below 2, implying that a two-photon up-conversion process takes place. Luminescence phenomena resulting from 2 and 3-photon up-conversion processes were presented for several glass host matrices [18,29,30]. Typical luminescence decay from the 2F5/2 state of Yb3+ is presented in Fig. 3.Luminescence decay curve given in semi-logarithmic scale is nearly linear, which proofs single-exponential decay behavior.

 

Fig. 3 Typical luminescence decay from the 2F5/2 state of Yb3+ in glass co-doped with 0.7Yb2O3/0.7Tb2O3.

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Based on luminescence decay measurements for 2F5/2 state of Yb3+ ions in glass samples without and with Tb3+, the Yb3+→Tb3+ energy transfer efficiency was determined. Dependence of 2F5/2 (Yb3+) lifetime and the energy transfer efficiency with terbium concentration is presented in Fig. 4.The 2F5/2 lifetime of Yb3+ is reduced from 882 μs (0.7Yb2O3) to 751 μs in the presence of Tb3+ (0.7Yb2O3/1Tb2O3). However, maximum upconversion luminescence was obtained in glass co-doped with 0.7Yb2O3/0.7Tb2O3. Increase in terbium content up to 1mol% results in concentration quenching of luminescence.

 

Fig. 4 Lifetime for 2F5/2 state of Yb3+ and energy transfer efficiency as a function of Tb3+ concentration.

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Ignoring the reverse transfer (Tb3+→Yb3+), quantum efficiency of the Yb3+→Tb3+ energy transfer can be established according to the equation:

η=1τYbYbTb/τYb
Efficiency of cooperative Yb3→Tb3+ energy transfer increases with increasing Tb3+ concentration, because distance between the interacting lanthanide ions is reduced. To determine the energy transfer coefficient Cf, the luminescence dynamics of Yb3+/Tb3+ dopants configuration needs to be scrutinized. The following Eq. (4) describes cooperative energy transfer and up-conversion processes:
dnYb1dt=RYb1nYb1+WYbnYb2dnYb2dt=RYb1nYb1WYbnYb2CfnYb22nTb1dnTb1dt=CfnYb22nTb1+WTbnTb2dnTb2dt=WTbnTb2+2CfnYb22nTb1NYb=nYb1+nYb2NTb=nTb1+nTb2
where: Cf - upconversion energy transfer coefficient, RYb - pump rate of Yb3+, nYb1, nYb2 and nTb1, nTb2 - population densities of Yb3+ and Tb3+, respectively.

From literature data it is well known that the reverse energy transfer also call back transfer process is not neglected for some glasses containing Tb3+ and Yb3+ ions [31]. Here, the concentrations of rare earth ions are relatively low and participation of back transfer process in population of Yb3+ and Tb3+ levels is rather not very significant. The equations do not take into account the reverse energy transfer (Tb3+→Yb3+) whose coefficient is several orders of magnitude smaller than Cf. Similar phenomena were observed for silicate glasses, where the calculated back transfer coefficient (Cb) was seven orders smaller than Yb3+→Tb3+ energy transfer coefficient [32]. The standard procedure of energy transfer coefficient determination based on least squares fitting of theory and experimental results was used [32,33]. The experimental and calculated results from decay curve of Tb3+:5D47F5 obtained for sample with 0.7Yb2O3/0.7Tb2O3 are presented in Fig. 5.

 

Fig. 5 Experimental and calculated decay curve of Tb3+: 5D47F5.

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The 5D4 luminescence lifetime of Tb3+ is equal to 1.98 ms. The Yb3+→Tb3+ energy transfer coefficient Cf close to 1.5∙10−33 cm6/s was determined by means of the nonlinear least squares fitting method. Root mean square is 1.41∙10−5 [s], which proofs reliability of performed calculations. The Cf value is greater than in the case of silicate glasses [33].

4. Conclusions

Up-conversion luminescence processes in GeO2-Ga2O3-BaO glass systems co-doped with Tb3+ and Yb3+ ions were studied. Emission bands due to 5D47FJ (J = 6, 5, 4, 3) and 5D3, 5G67FJ (J = 6, 5, 4) transitions of Tb3+ ions are observed under direct diode-laser excitation of Yb3+ by 976 nm line. Energy transfer coefficient in glass co-doped with 0.7Yb2O3/0.7Tb2O3 amounts to Cf = 1.5∙10−33 cm6/s while efficiency of the Yb3+→Tb3+ energy transfer is 12%.

Acknowledgments

This work was supported by National Science Centre (Poland) – grant No. N N515 512340

References and links

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2. P. Xie and T. R. Gosnell, “Room-temperature upconversion fiber laser tunable in the red, orange, green, and blue spectral regions,” Opt. Lett. 20(9), 1014–1016 (1995). [CrossRef]   [PubMed]  

3. Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett. 37(4), 521–523 (2012). [CrossRef]   [PubMed]  

4. Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett. 90, 021107 (2007). [CrossRef]  

5. Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys. 110(11), 113503 (2011). [CrossRef]  

6. X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B 96(1), 51–55 (2009). [CrossRef]  

7. P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys. 110(12), 123527 (2011). [CrossRef]  

8. Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B 30(2), 456–459 (2013). [CrossRef]  

9. A. Lin, X. Liu, P. R. Watekar, H. Guo, B. Peng, W. Wei, M. Lu, W. T. Han, and J. Toulouse, “Intense green upconversion emission in Tb3+/Yb3+ codoped alumino-germano-silicate optical fibers,” Appl. Opt. 49(9), 1671–1675 (2010). [CrossRef]   [PubMed]  

10. L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett. 90(13), 131116 (2007). [CrossRef]  

11. D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C 113(16), 6406–6410 (2009). [CrossRef]  

12. M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin . 102-103, 762–767 (2003).

13. Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys. 105(8), 083105 (2009). [CrossRef]  

14. J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci. 208(8), 1827–1832 (2011). [CrossRef]  

15. Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B 98(2-3), 261–265 (2010). [CrossRef]  

16. I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys. 89(5), 2520–2524 (2001). [CrossRef]  

17. V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater. 33(2), 159–163 (2010). [CrossRef]  

18. A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids 354(2-9), 509–514 (2008). [CrossRef]  

19. M. Peng, N. Zhang, L. Wondraczek, J. Qiu, Z. Yang, and Q. Zhang, “Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses,” Opt. Express 19(21), 20799–20807 (2011). [CrossRef]   [PubMed]  

20. B. Zhou, H. Lin, B. Chen, and E. Y. B. Pun, “Superbroadband near-infrared emission in Tm-Bi codoped sodium-germanium-gallate glasses,” Opt. Express 19(7), 6514–6523 (2011). [CrossRef]   [PubMed]  

21. Y. Messaddeq, S. J. L. Ribeiro, E. Pecoraro, and E. M. Nascimento, “Glass for optical amplifier fiber,” US Patent No 7,773,647 B2 (Aug. 10, 2010)

22. D. M. McPherson and S. C. Murray, “Germanate glass for mid-infrared medical optical fiber,” US Patent No 5,491,767 (Feb. 13, 1996)

23. D. L. Yang, H. Gong, E. Y. B. Pun, X. Zhao, and H. Lin, “Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery,” Opt. Express 18(18), 18997–19008 (2010). [CrossRef]   [PubMed]  

24. B. J. Chen, L. F. Shen, E. Y. B. Pun, and H. Lin, “Sm3+-doped germanate glass channel waveguide as light source for minimally invasive photodynamic therapy surgery,” Opt. Express 20(2), 879–889 (2012). [CrossRef]   [PubMed]  

25. J. Yang, B. J. Chen, E. Y. B. Pun, B. Zhai, and H. Lin, “Pr3+-doped heavy metal germanium tellurite glasses for irradiative light source in minimally invasive photodynamic therapy surgery,” Opt. Express 21(1), 1030–1040 (2013). [CrossRef]   [PubMed]  

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28. J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp. 495(1), 205–208 (2010). [CrossRef]  

29. R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp. 509(18), 5591–5595 (2011). [CrossRef]  

30. N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B 89(2-3), 345–348 (2007). [CrossRef]  

31. E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun. 158(1-6), 61–64 (1998).

32. T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B 26(4), 819–829 (2009). [CrossRef]  

33. T. Yamashita, Y. Ohishi, “Energy transfer and gain analysis for Tb3+-Yb3+ co-doped silicate glasses under the 0.98 µm excitation,” OSA / CLEO/QELS, 1–2 (2008).

References

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  1. D. Lande, S. S. Orlov, A. Akella, L. Hesselink, and R. R. Neurgaonkar, “Digital holographic storage system incorporating optical fixing,” Opt. Lett.22(22), 1722–1724 (1997).
    [CrossRef] [PubMed]
  2. P. Xie and T. R. Gosnell, “Room-temperature upconversion fiber laser tunable in the red, orange, green, and blue spectral regions,” Opt. Lett.20(9), 1014–1016 (1995).
    [CrossRef] [PubMed]
  3. Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
    [CrossRef] [PubMed]
  4. Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
    [CrossRef]
  5. Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
    [CrossRef]
  6. X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
    [CrossRef]
  7. P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
    [CrossRef]
  8. Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
    [CrossRef]
  9. A. Lin, X. Liu, P. R. Watekar, H. Guo, B. Peng, W. Wei, M. Lu, W. T. Han, and J. Toulouse, “Intense green upconversion emission in Tb3+/Yb3+ codoped alumino-germano-silicate optical fibers,” Appl. Opt.49(9), 1671–1675 (2010).
    [CrossRef] [PubMed]
  10. L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
    [CrossRef]
  11. D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
    [CrossRef]
  12. M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).
  13. Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
    [CrossRef]
  14. J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci.208(8), 1827–1832 (2011).
    [CrossRef]
  15. Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
    [CrossRef]
  16. I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
    [CrossRef]
  17. V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
    [CrossRef]
  18. A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
    [CrossRef]
  19. M. Peng, N. Zhang, L. Wondraczek, J. Qiu, Z. Yang, and Q. Zhang, “Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses,” Opt. Express19(21), 20799–20807 (2011).
    [CrossRef] [PubMed]
  20. B. Zhou, H. Lin, B. Chen, and E. Y. B. Pun, “Superbroadband near-infrared emission in Tm-Bi codoped sodium-germanium-gallate glasses,” Opt. Express19(7), 6514–6523 (2011).
    [CrossRef] [PubMed]
  21. Y. Messaddeq, S. J. L. Ribeiro, E. Pecoraro, and E. M. Nascimento, “Glass for optical amplifier fiber,” US Patent No 7,773,647 B2 (Aug. 10, 2010)
  22. D. M. McPherson and S. C. Murray, “Germanate glass for mid-infrared medical optical fiber,” US Patent No 5,491,767 (Feb. 13, 1996)
  23. D. L. Yang, H. Gong, E. Y. B. Pun, X. Zhao, and H. Lin, “Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery,” Opt. Express18(18), 18997–19008 (2010).
    [CrossRef] [PubMed]
  24. B. J. Chen, L. F. Shen, E. Y. B. Pun, and H. Lin, “Sm3+-doped germanate glass channel waveguide as light source for minimally invasive photodynamic therapy surgery,” Opt. Express20(2), 879–889 (2012).
    [CrossRef] [PubMed]
  25. J. Yang, B. J. Chen, E. Y. B. Pun, B. Zhai, and H. Lin, “Pr3+-doped heavy metal germanium tellurite glasses for irradiative light source in minimally invasive photodynamic therapy surgery,” Opt. Express21(1), 1030–1040 (2013).
    [CrossRef] [PubMed]
  26. J. Wu, Z. Yao, J. Zong, and S. Jiang, “Highly efficient high-power thulium-doped germanate glass fiber laser,” Opt. Lett.32(6), 638–640 (2007).
    [CrossRef] [PubMed]
  27. D. L. Yang, E. Y. B. Pun, B. J. Chen, and H. Lin, “Radiative transitions and optical gains in Er3+/Yb3+ codoped acid-resistant ion exchanged germanate glass channel waveguides,” JOSA B26(2), 357–363 (2009).
    [CrossRef]
  28. J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
    [CrossRef]
  29. R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
    [CrossRef]
  30. N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
    [CrossRef]
  31. E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).
  32. T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B26(4), 819–829 (2009).
    [CrossRef]
  33. T. Yamashita, Y. Ohishi, “Energy transfer and gain analysis for Tb3+-Yb3+ co-doped silicate glasses under the 0.98 µm excitation,” OSA / CLEO/QELS, 1–2 (2008).

2013

2012

2011

B. Zhou, H. Lin, B. Chen, and E. Y. B. Pun, “Superbroadband near-infrared emission in Tm-Bi codoped sodium-germanium-gallate glasses,” Opt. Express19(7), 6514–6523 (2011).
[CrossRef] [PubMed]

M. Peng, N. Zhang, L. Wondraczek, J. Qiu, Z. Yang, and Q. Zhang, “Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses,” Opt. Express19(21), 20799–20807 (2011).
[CrossRef] [PubMed]

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
[CrossRef]

J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci.208(8), 1827–1832 (2011).
[CrossRef]

2010

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

A. Lin, X. Liu, P. R. Watekar, H. Guo, B. Peng, W. Wei, M. Lu, W. T. Han, and J. Toulouse, “Intense green upconversion emission in Tb3+/Yb3+ codoped alumino-germano-silicate optical fibers,” Appl. Opt.49(9), 1671–1675 (2010).
[CrossRef] [PubMed]

D. L. Yang, H. Gong, E. Y. B. Pun, X. Zhao, and H. Lin, “Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery,” Opt. Express18(18), 18997–19008 (2010).
[CrossRef] [PubMed]

2009

T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B26(4), 819–829 (2009).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

D. L. Yang, E. Y. B. Pun, B. J. Chen, and H. Lin, “Radiative transitions and optical gains in Er3+/Yb3+ codoped acid-resistant ion exchanged germanate glass channel waveguides,” JOSA B26(2), 357–363 (2009).
[CrossRef]

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

2008

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

2007

Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
[CrossRef]

J. Wu, Z. Yao, J. Zong, and S. Jiang, “Highly efficient high-power thulium-doped germanate glass fiber laser,” Opt. Lett.32(6), 638–640 (2007).
[CrossRef] [PubMed]

2003

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

2001

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

1998

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

1997

1995

Afonso, A. C. M.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

Akella, A.

Arai, Y.

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Bueno, L. A.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

Cao, W.

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
[CrossRef] [PubMed]

Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
[CrossRef] [PubMed]

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Cassanjes, F. C.

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Chen, B.

Chen, B. J.

Chen, D.

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Chen, G.

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

Cheng, J.

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Costa, E. B.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

da Costa, B. J.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

de Araujo, C. B.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

de Araujo, M. T.

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Delben, J. R.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

Ding, J.

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Dong, G.

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

dos Santos, P. V.

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Duan, Q.

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
[CrossRef] [PubMed]

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Giri, N. K.

N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
[CrossRef]

Gomes, A. S. L.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

Gong, H.

Gosnell, T. R.

Gouveia-Neto, A. S.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Guo, H.

Han, W. T.

Hesselink, L.

Huang, L.

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Huang, P.

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

Jha, A.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Jiang, S.

Jose, G.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Jose, R.

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Lakshminarayana, G.

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Lande, D.

Lin, A.

Lin, G.

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Lin, H.

Liu, X.

A. Lin, X. Liu, P. R. Watekar, H. Guo, B. Peng, W. Wei, M. Lu, W. T. Han, and J. Toulouse, “Intense green upconversion emission in Tb3+/Yb3+ codoped alumino-germano-silicate optical fibers,” Appl. Opt.49(9), 1671–1675 (2010).
[CrossRef] [PubMed]

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Lu, M.

Martín, I. R.

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

Martins, E.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

Mendez-Ramos, J.

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

Messaddeq, Y.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

Molina, P.

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

Nascimento, J. F.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

Neurgaonkar, R. R.

Ohishi, Y.

T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B26(4), 819–829 (2009).
[CrossRef]

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Orlov, S. S.

Pan, Y. X.

Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
[CrossRef]

Peng, B.

Peng, M.

Pun, E. Y. B.

Qian, B.

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

Qiao, Y.

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Qin, F.

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
[CrossRef] [PubMed]

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Qiu, J.

M. Peng, N. Zhang, L. Wondraczek, J. Qiu, Z. Yang, and Q. Zhang, “Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses,” Opt. Express19(21), 20799–20807 (2011).
[CrossRef] [PubMed]

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Rai, D. K.

R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
[CrossRef]

N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
[CrossRef]

Rai, S. B.

R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
[CrossRef]

N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
[CrossRef]

Ribeiro, S. J. L.

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Richards, B.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Rodriguez, V. D.

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

Scarnera, V.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Shen, L. F.

Shimamura, K.

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

Stacey, C.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Suzuki, T.

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Tanabe, S.

J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci.208(8), 1827–1832 (2011).
[CrossRef]

Torres, M. E.

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

Toulouse, J.

Ueda, J.

J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci.208(8), 1827–1832 (2011).
[CrossRef]

Vasyliev, V.

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

Verma, R. K.

R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
[CrossRef]

Vermelho, M. V. D.

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

Villora, E. G.

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

Wang, D.

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Wang, P.

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

Wang, Y.

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

Watekar, P. R.

Wei, W.

Weng, F.

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

Wondraczek, L.

Wu, J.

Xie, P.

Xu, W.

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Xu, Y.

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

Yamashita, T.

T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B26(4), 819–829 (2009).
[CrossRef]

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

Yanes, A. C.

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

Yang, C. H.

Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
[CrossRef]

Yang, D. L.

D. L. Yang, H. Gong, E. Y. B. Pun, X. Zhao, and H. Lin, “Rare-earth ions doped heavy metal germanium tellurite glasses for fiber lighting in minimally invasive surgery,” Opt. Express18(18), 18997–19008 (2010).
[CrossRef] [PubMed]

D. L. Yang, E. Y. B. Pun, B. J. Chen, and H. Lin, “Radiative transitions and optical gains in Er3+/Yb3+ codoped acid-resistant ion exchanged germanate glass channel waveguides,” JOSA B26(2), 357–363 (2009).
[CrossRef]

Yang, J.

Yang, Z.

Yao, Z.

Ye, S.

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Yu, Y.

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

Zhai, B.

Zhang, N.

Zhang, Q.

M. Peng, N. Zhang, L. Wondraczek, J. Qiu, Z. Yang, and Q. Zhang, “Ultrabroad NIR luminescence and energy transfer in Bi and Er/Bi co-doped germanate glasses,” Opt. Express19(21), 20799–20807 (2011).
[CrossRef] [PubMed]

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

Zhang, Q. Y.

Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
[CrossRef]

Zhang, Z.

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

Q. Duan, F. Qin, Z. Zhang, W. Cao, and W. Cao, “Quantum cutting mechanism in NaYF4:Tb3+, Yb3+.,” Opt. Lett.37(4), 521–523 (2012).
[CrossRef] [PubMed]

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

Zhao, X.

Zhou, B.

Zhou, Q.

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

Zhu, B.

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Zong, J.

Appl. Opt.

Appl. Phys. B

N. K. Giri, D. K. Rai, and S. B. Rai, “UV-visible emission in Tb-Yb codoped tellurite glass on 980-nm excitation,” Appl. Phys. B89(2-3), 345–348 (2007).
[CrossRef]

Q. Zhang, G. Chen, Y. Xu, X. Liu, B. Qian, G. Dong, Q. Zhou, J. Qiu, and D. Chen, “Abnormal upconversion luminescence from Yb3+ doped and Tb3+/Yb3+ codoped high silica glasses induced by intrinsic optical bistability,” Appl. Phys. B98(2-3), 261–265 (2010).
[CrossRef]

X. Liu, S. Ye, Y. Qiao, G. Dong, B. Zhu, D. Chen, G. Lakshminarayana, and J. Qiu, “Cooperative downconversion and near-infrared luminescence of Tb3+–Yb3+ codoped lanthanum borogermanate glasses,” Appl. Phys. B96(1), 51–55 (2009).
[CrossRef]

Appl. Phys. Lett.

Q. Y. Zhang, C. H. Yang, and Y. X. Pan, “Cooperative quantum cutting in one-dimentional (YbxGd1-x)Al3(BO3)4:Tb3+,” Appl. Phys. Lett.90, 021107 (2007).
[CrossRef]

L. Huang, T. Yamashita, R. Jose, Y. Arai, T. Suzuki, and Y. Ohishi, “Intense ultraviolet emission from Tb3+ and Yb3+ codoped glass ceramic containing CaF2 nanocrystals,” Appl. Phys. Lett.90(13), 131116 (2007).
[CrossRef]

J. Alloy. Comp.

J. Ding, Q. Zhang, J. Cheng, X. Liu, G. Lin, J. Qiu, and D. Chen, “Multicolor upconversion luminescence from RE3+-Yb3+ (RE = Er, Tm, Tb) codoped LaAlGe2O7 glasses,” J. Alloy. Comp.495(1), 205–208 (2010).
[CrossRef]

R. K. Verma, D. K. Rai, and S. B. Rai, “Investigation of structural properties and its effect on optical properties: Yb3+/Tb3+ codoped in aluminum silicate glass,” J. Alloy. Comp.509(18), 5591–5595 (2011).
[CrossRef]

J. Appl. Phys.

Q. Duan, F. Qin, D. Wang, W. Xu, J. Cheng, Z. Zhang, and W. Cao, “Quantum cutting mechanism in Tb3+-Yb3+ co-doped oxyfluoride glass,” J. Appl. Phys.110(11), 113503 (2011).
[CrossRef]

P. Molina, V. Vasyliev, E. G. Villora, and K. Shimamura, “Tb3+-Yb3+ cooperative down and up conversion processes in Tb0.81Ca0.19F2.81:Yb3+ single crystals,” J. Appl. Phys.110(12), 123527 (2011).
[CrossRef]

Y. Arai, T. Yamashita, T. Suzuki, and Y. Ohishi, “Upconversion properties of Tb3+-Yb3+ codoped fluorophosphate glasses,” J. Appl. Phys.105(8), 083105 (2009).
[CrossRef]

I. R. Martín, A. C. Yanes, J. Mendez-Ramos, M. E. Torres, and V. D. Rodriguez, “Cooperative energy transfer in Yb3+–Tb3+ codoped silica sol-gel glasses,” J. Appl. Phys.89(5), 2520–2524 (2001).
[CrossRef]

J. Lumin

M. V. D. Vermelho, P. V. dos Santos, M. T. de Araujo, A. S. Gouveia-Neto, F. C. Cassanjes, S. J. L. Ribeiro, and Y. Messaddeq, “Thermally enhanced cooperative energy-transfer frequency upconversion in terbium and ytterbium doped tellurite glass,” J. Lumin. 102-103, 762–767 (2003).

J. Non-Cryst. Solids

A. S. Gouveia-Neto, L. A. Bueno, A. C. M. Afonso, J. F. Nascimento, E. B. Costa, Y. Messaddeq, and S. J. L. Ribeiro, “Upconversion luminescence in Ho3+/Yb3+- and Tb3+/Yb3+-codoped fluorogermanate glass and glass ceramic,” J. Non-Cryst. Solids354(2-9), 509–514 (2008).
[CrossRef]

J. Phys. Chem. C

D. Chen, Y. Yu, Y. Wang, P. Huang, and F. Weng, “Cooperative energy transfer up-conversion and quantum cutting down-conversion in Yb3+:TbF3 nanocrystals embedded glass ceramics,” J. Phys. Chem. C113(16), 6406–6410 (2009).
[CrossRef]

JOSA B

Q. Duan, F. Qin, P. Wang, Z. Zhang, and W. Cao, “Upconversion emission efficiency of Tb3+-Yb3+ co-doped glass,” JOSA B30(2), 456–459 (2013).
[CrossRef]

T. Yamashita and Y. Ohishi, “Analysis of energy transfers between Tb3+ and Yb3+ codoped in borosilicate glasses,” JOSA B26(4), 819–829 (2009).
[CrossRef]

D. L. Yang, E. Y. B. Pun, B. J. Chen, and H. Lin, “Radiative transitions and optical gains in Er3+/Yb3+ codoped acid-resistant ion exchanged germanate glass channel waveguides,” JOSA B26(2), 357–363 (2009).
[CrossRef]

Opt. Commun.

E. Martins, C. B. de Araujo, J. R. Delben, A. S. L. Gomes, B. J. da Costa, and Y. Messaddeq, “Cooperative frequency upconversion in Yb3+–Tb3+ codoped fluoroindate glass,” Opt. Commun.158(1-6), 61–64 (1998).

Opt. Express

Opt. Lett.

Opt. Mater.

V. Scarnera, B. Richards, A. Jha, G. Jose, and C. Stacey, “Green up-conversion in Yb3+–Tb3+ and Yb3+–Tm3+–Tb3+ doped fluoro-germanate bulk glass and fibre,” Opt. Mater.33(2), 159–163 (2010).
[CrossRef]

Phys. Status Solidi., A Appl. Mater. Sci.

J. Ueda and S. Tanabe, “Sensitization mechanisms of 1μm luminescence in Tb3+-Yb3+ co-doped borate glasses,” Phys. Status Solidi., A Appl. Mater. Sci.208(8), 1827–1832 (2011).
[CrossRef]

Other

Y. Messaddeq, S. J. L. Ribeiro, E. Pecoraro, and E. M. Nascimento, “Glass for optical amplifier fiber,” US Patent No 7,773,647 B2 (Aug. 10, 2010)

D. M. McPherson and S. C. Murray, “Germanate glass for mid-infrared medical optical fiber,” US Patent No 5,491,767 (Feb. 13, 1996)

T. Yamashita, Y. Ohishi, “Energy transfer and gain analysis for Tb3+-Yb3+ co-doped silicate glasses under the 0.98 µm excitation,” OSA / CLEO/QELS, 1–2 (2008).

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Figures (5)

Fig. 1
Fig. 1

Emission spectra for Yb3+/Tb3+ co-doped germanate glasses. Inset shows dependence of upconversion emission intensity of 0.7Yb3+/0.7Tb3+ co-doped germanate glass on excitation power (λp = 976 nm).

Fig. 2
Fig. 2

Simplified energy level diagram of Tb3+/Yb3+ ion and possible upconversion luminescence mechanisms.

Fig. 3
Fig. 3

Typical luminescence decay from the 2F5/2 state of Yb3+ in glass co-doped with 0.7Yb2O3/0.7Tb2O3.

Fig. 4
Fig. 4

Lifetime for 2F5/2 state of Yb3+ and energy transfer efficiency as a function of Tb3+ concentration.

Fig. 5
Fig. 5

Experimental and calculated decay curve of Tb3+: 5D47F5.

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

2 × Yb 3 + ( 2 F 5 / 2 ) + Tb 3 + ( 7 F 6 ) 2 × Yb 3 + ( 2 F 7 / 2 ) + Tb 3 + ( 5 D 4 )
Tb 3 + ( 5 D 4 ) + Yb 3 + ( 2 F 5 / 2 ) + h ν relaxation , Tb 3 + ( 5 D 3 )                
d n Yb1 dt = R Yb1 n Yb1 + W Yb n Yb2 d n Yb2 dt = R Yb1 n Yb1 W Yb n Yb2 C f n Yb2 2 n Tb1 d n Tb1 dt = C f n Yb2 2 n Tb1 + W Tb n Tb2 d n Tb2 dt = W Tb n Tb2 +2 C f n Yb2 2 n Tb1 N Yb = n Yb1 + n Yb2 N Tb = n Tb1 + n Tb2

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