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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 15, Iss. 15 — Jul. 23, 2007
  • pp: 9535–9540
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Broadband telecommunication wavelength emission in Yb3+-Er3+-Tm3+ co-doped nano-glass-ceramics

V.K. Tikhomirov, K. Driesen, C. Görller-Walrand, and M. Mortier  »View Author Affiliations


Optics Express, Vol. 15, Issue 15, pp. 9535-9540 (2007)
http://dx.doi.org/10.1364/OE.15.009535


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Abstract

Transparent Yb3+, Er3+ and Tm3+ co-doped nano-glass-ceramics 32(SiO2)9(AlO1.5)31.5(CdF2)18.5(PbF2)5.5(ZnF2):3.5(Yb-Er-TmF3), mol%, have been prepared where co-dopants mostly partition in nano-crystals Pb1-x(Yb3+,Er3+,Tm3+)xF2+x embedded in the glass network. The Yb3+ ensures high absorption at 980 nm telecommunication pump wavelength and further phonon-mediated energy transfer to Er3+ and Tm3+ co-dopants. Er3+ and Tm3+ radiate overlapping emission bands from their lowest energy levels, with similar lifetime of about 9 ms, which cover the range between 1.50 to 1.70 µm. The lifetime of all higher levels of Er3+ and Tm3+ dopants is shorter than 70 µs due to short inter-dopant distances in the nano-crystals resulting in fast energy transfer to their lowest levels.

© 2007 Optical Society of America

1. Introduction

Broadband infrared emission of rare-earth dopants is of primary importance in several high tech areas such as optical amplifiers and laser sources operating in the wavelength range of the extended telecommunication window of 1.2 to 1.7 µm [1

1. G.C. Thomas, B.I. Shraiman, P.F. Glodis, and M.J. Stephen, “Towards the clarity limit in optical fibre,” Nature (London) 404, 262–264 (2000). [CrossRef]

10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

]. The most successful dopant has been the Er3+ due to its efficient radiative transition 4I13/24I15/2, Fig. 1(a), with long-living lasing level 4I13/2, which occurs at about 1.53 to 1.56 µm and coincides with the wavelength minimum of optical loss in currently used telecommunication optical fibres (C-band) [1

1. G.C. Thomas, B.I. Shraiman, P.F. Glodis, and M.J. Stephen, “Towards the clarity limit in optical fibre,” Nature (London) 404, 262–264 (2000). [CrossRef]

4

4. S. Sudo (Ed.), Optical Fibre Amplifiers: Materials, Devices, and Applications. (Artech House Inc., Boston, 1997).

and refs therein]. The Tm3+ dopant has also been considered for optical amplification in telecommunication fibres at wavelengths from about 1.45 to 1.48 µm (S-band) corresponding to the 3H43F4 transition of the Tm3+, Fig. 1(a), however the terminating level 3F4 has very long life-time preventing efficient population inversion for the 3H43F4 transition [3

3. P.C. Becker, N.A. Olsson, and J.R. Simpson, Erbium-doped Fibre Amplifiers: Fundamentals and Technology, (Academic, San Diego, 1999).

,4

4. S. Sudo (Ed.), Optical Fibre Amplifiers: Materials, Devices, and Applications. (Artech House Inc., Boston, 1997).

and refs therein].

Yb3+ is known as useful co-dopant both for the Er3+ and Tm3+-dopants due to the unique high absorption cross-section transition 2F5/22F7/2 of the Yb3+ (Fig. 1) coincident with a traditional pump wavelength of telecommunication systems at 980 nm [2

2. E. Desurvire, Erbium-doped Fibre Amplifiers: Materials, Devices and Applications. (Wiley, New York, 1994).

4

4. S. Sudo (Ed.), Optical Fibre Amplifiers: Materials, Devices, and Applications. (Artech House Inc., Boston, 1997).

]. The excited Yb3+ ion efficiently transfers the energy both to the Er3+ and Tm3+ co-dopants [11

11. J.F. Suyver, J. Grimm, M.K. van Veen, D. Biner, K.W. Krämer, and H.U. Güdel, “Upconversion spectroscopy and properties of NaYF4 doped with Er3+, Tm3+ and/or Yb3+,” J. Lumin. 117, 1–12 (2006). [CrossRef]

,12

12. F. Auzel “Upconversion and Anti-Stokes processes with f and d Ions in Solids,” Chem. Rev. 105, 139–173 (2004). [CrossRef]

and refs therein], which consequently emit.

In this work we show that Yb3+-Er3+-Tm3+ co-doped oxyfluoride glass-ceramics 32(SiO2)9(AlO1.5)31.5(CdF2)18.5(PbF2)5.5(ZnF2): 1.5(YbF3)1.0(ErF3)1.0(TmF3), mol%, provides overlapping emission bands of the Er3+ (4I13/24I15/2 transition) and the Tm3+ (3F43H6 transition) resulting in an entire infrared emission band covering range between about 1.5 to 1.7 µm with a common lifetime of about 9 ms. Contrary and fortunately, the lifetimes of all higher levels of the Er3+ and Tm3+ have been found to be shorter than 70 µs due to efficient energy transfer to the 4I13/2 of the Er3+ and 3F4 of the Tm3+, which may result in high population inversion of these known lasing levels 4I13/2 of the Er3+ and 3F4 of the Tm3+. This has a potential for optical amplification/lasing of this nano-glass-ceramics at the wavelengths range from about 1.5 to 1.7 µm, which covers a substantial part of the available extended telecommunication window of 1.2 to 1.7 µm [1

1. G.C. Thomas, B.I. Shraiman, P.F. Glodis, and M.J. Stephen, “Towards the clarity limit in optical fibre,” Nature (London) 404, 262–264 (2000). [CrossRef]

]. The mechanism for the efficient energy transfer between excited levels of the Yb3+, Er3+, Tm3+ co-dopants has been discussed by comparing the room and low temperature emission spectra and lifetimes of the dopants in the nano-glass-ceramics and its precursor glass.

Fig. 1. a) Energy level diagram of the Tm3+, Yb3+ and Er3+. The excitation and emission transitions of interest are indicated by arrows, respectively. b) Absorbance spectra of the GC (thick line) and precursor glass (thin line) at room temperature; some absorption transitions are postsigned.

2. Experimental

The precursor oxyfluoride glass 32(SiO2)9(AlO1.5)31.5(CdF2)18.5(PbF2)5.5(ZnF2): 1.5(YbF3)1.0(ErF3)1.0(TmF3) mol% has been prepared by melting the batch consisting of the respective oxides and fluorides at about 1000°C for 1 hour [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

]. The melt has been quenched in air atmosphere into the brass mould. The corresponding nano-glass-ceramics (GC) has been obtained on heat-treatment of the precursor glass at about 440°C for 30 minutes. The alternative procedure for preparation of GC consists in irradiation of the precursor glass by tightly focused laser beam (direct laser writing) resulting in local heating of the glass and precipitation of the GC in the irradiated areas [13

13. V.K. Tikhomirov, J. Koch, D. Wand, and B. Chichkov, “Fabrication of buried waveguides and nano-crystals in Er3+-doped oxyfluoride glass,” Phys. Status Solidi (a) 202, R73–R75 (2005). [CrossRef]

].

On the heat-treatment of this precursor glass, the rare-earth dopants nucleate the size-restricted growth of nano-crystals of nearly cubic β-PbF2 [5

5. G. Dantelle, M. Mortier, D. Vivien, and G. Patriarche, “Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics,” Opt. Mater. 28, 638–642 (2006). [CrossRef]

,7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,9

9. K. Driesen, V.K. Tikhomirov, C. Görller-Walrand, V.D. Rodríguez, and A.B. Seddon, “Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission,” Appl. Phys. Lett.88, art.073111 (2006). [CrossRef]

,10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

] to the fixed diameter of about 8 nm, as measured by means of transmission electron microscopy (TEM) [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

], x-ray diffraction (XRD) [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,9

9. K. Driesen, V.K. Tikhomirov, C. Görller-Walrand, V.D. Rodríguez, and A.B. Seddon, “Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission,” Appl. Phys. Lett.88, art.073111 (2006). [CrossRef]

,10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

]. Since the dopants nucleate the growth of the nano-crystalline phase [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

], these nano-crystals are very heavily doped with rare-earth atoms and may thereby form stoichiometric compound of tveitite type, e.g. Pb1-xLnxF2+x [5

5. G. Dantelle, M. Mortier, D. Vivien, and G. Patriarche, “Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics,” Opt. Mater. 28, 638–642 (2006). [CrossRef]

,10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

]; where Ln stands for a rare-earth ion, e.g. Yb3+, Er3+, Tm3+, and x≈0.3 [10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

], which has a structure similar to the face centered cubic β-PbF2 [14

14. S. Hull, “Superionics crystal structures and conduction processes,” Rep. Prog. Phys. 67, 1233–1314 (2004). [CrossRef]

,15

15. D.J.M. Bevan, J. Strähle, and O. Greis, “The crystal-structure of tveitite, an ordered yttrofluorite mineral,” J. Solid State Chem. 44, 75–81 (1982). [CrossRef]

]. Thus, we assume that the actual chemical composition of the nano-crystals may approach the Pb3(Yb-Er-Tm)1F9, where the ratio of Yb:Er:Tm probably nearly follows the ratio 1.5:1:1 corresponding to their ratio in the batch. The super-ionic phase transition observed in the β-PbF2 and tveitite-type crystals near to 440°C [14

14. S. Hull, “Superionics crystal structures and conduction processes,” Rep. Prog. Phys. 67, 1233–1314 (2004). [CrossRef]

] does obviously help in diffusion of F- ions into the Pb1-xLnxF2+x nano-crystals for required charge compensation since the valence of Ln3+ substitute is higher than of Pb2+. It suggests that the heat-treatment of the precursor glass should be carried out at about 440°C, which actually corresponds to the nano-crystallization peak in the differential thermal analysis (DTA) curve of the precursor glass [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

].

3. Results and discussion

Figure 1(b) shows room temperature absorbance spectra of the GC and its precursor glass; some absorption bands corresponding to the Yb3+, Er3+and Tm3+ dopants have been post-signed. It is seen that the broad absorption band, 2F5/22F7/2, of a characteristic shape of the Yb3+ at about 0.98 µm dominates the absorption spectrum pointing out its use for optical pump. This band masks a substantially weaker and narrower absorption band 4I11/24I15/2 of the Er3+, which is also present at about 0.98 µm [2

2. E. Desurvire, Erbium-doped Fibre Amplifiers: Materials, Devices and Applications. (Wiley, New York, 1994).

8

8. V. Rodriguez, V.K. Tikhomirov, J. Mendez-Ramos, and A.B. Seddon, “The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics,” Europhys. Lett. 69, 128–134 (2005). [CrossRef]

]. Other characteristic bands of the Er3+ and Tm3+, post-signed in Fig. 1(b), are also present in the absorption spectrum indicative that all dopants have been quite well dissolved both in the precursor glass and corresponding GC. Also, a characteristic change in the shape of the absorption bands with nano-ceramming of the precursor glass can be seen in Fig. 1(b), e.g. for the band 4I13/24I15/2 of the Er3+ [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

] and for the 3F43H6 band of the Tm3+ [16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

] indicative that in the GC the dopants partition in the nano-crystalline phase of β-PbF2 type [5

5. G. Dantelle, M. Mortier, D. Vivien, and G. Patriarche, “Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics,” Opt. Mater. 28, 638–642 (2006). [CrossRef]

,7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

,16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

] making the yttrofluorite type nano-crystals [10

10. V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

,14

14. S. Hull, “Superionics crystal structures and conduction processes,” Rep. Prog. Phys. 67, 1233–1314 (2004). [CrossRef]

,15

15. D.J.M. Bevan, J. Strähle, and O. Greis, “The crystal-structure of tveitite, an ordered yttrofluorite mineral,” J. Solid State Chem. 44, 75–81 (1982). [CrossRef]

]. The percentage of rare-earth dopant in the nano-crystalline phase in this GC has been estimated to be as high as about 90% [8

8. V. Rodriguez, V.K. Tikhomirov, J. Mendez-Ramos, and A.B. Seddon, “The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics,” Europhys. Lett. 69, 128–134 (2005). [CrossRef]

,9

9. K. Driesen, V.K. Tikhomirov, C. Görller-Walrand, V.D. Rodríguez, and A.B. Seddon, “Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission,” Appl. Phys. Lett.88, art.073111 (2006). [CrossRef]

].

Fig. 2. a) room temperature emission spectra of the Yb3+-Er3+-Tm3+ co-doped GC (thick solid line) and precursor glass (thin solid line) excited at 900 nm. b) emission spectra of the Yb3+-Er3+-Tm3+ co-doped GC at 77 K excited at 900 nm (into Yb3+ absorption band, dot line), 522 nm (into Er3+ absorption band, thick line) and 463 nm (into Tm3+ absorption band, thin solid line).

Figure 2(a) shows steady state room temperature emission spectra of GC and precursor glass when excited at 900 nm, i.e. at the high energy onset of the absorption band of the Yb3+ (neither Er3+ nor Tm3+ absorb at this wavelength, e.g. [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

]). We see in Fig. 2(a) that in addition to the emission band of the Yb3+ (1.0 µm) and weak emission band of the Tm3+ (observed only in GC at 1.2 µm), the spectrum is dominated by the broad emission band covering in particular the range between 1.5 to 1.7 µm and consisting of the overlapping emission bands of the Er3+ (1.55 µm transition 4I13/24I15/2), and Tm3+ (the 1.64 µm high-energy shoulder of the transition 3F43H6 [16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

]). The shape of the bands of the Er3+ and Tm3+ co-dopants is similar to the shape of the respectively single Er3+ [7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,8

8. V. Rodriguez, V.K. Tikhomirov, J. Mendez-Ramos, and A.B. Seddon, “The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics,” Europhys. Lett. 69, 128–134 (2005). [CrossRef]

] and Tm3+ [16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

] doped glasses and GC’s of the same host chemical composition. Of special importance/interest here is a high energy shoulder of the Tm3+ band at 1.64 µm, which increases drastically in GC compared to the precursor glass, as it has been noted also for the single Tm3+-doped GC [16

16. M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

]. The weak shoulder at 1.60 µm belongs to the emission band of the Er3+ [8

8. V. Rodriguez, V.K. Tikhomirov, J. Mendez-Ramos, and A.B. Seddon, “The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics,” Europhys. Lett. 69, 128–134 (2005). [CrossRef]

]. The response function of the spectrometer has been taken into account in this work, while we used for detection of emission a liquid nitrogen cooled photomultiplier and InSb photodetector. A stronger emission of the Tm3+ at 1.64 µm than of the Er3+ at 1.55 µm may be practically useful due to higher optical loss of the telecommunication fibres at 1.64 µm compared to 1.55 µm [1

1. G.C. Thomas, B.I. Shraiman, P.F. Glodis, and M.J. Stephen, “Towards the clarity limit in optical fibre,” Nature (London) 404, 262–264 (2000). [CrossRef]

]. We found the ratio of these bands of the Tm3+ and Er3+ can be adjusted according to the purpose by changing the ratio of Tm3+ to Er3+ in the batch. Actually, current attempts to broaden the amplification band of existing telecommunications focuses on use of the L-band of telecommunication fibres, especially at about 1.58 to 1.65 µm [2

2. E. Desurvire, Erbium-doped Fibre Amplifiers: Materials, Devices and Applications. (Wiley, New York, 1994).

4

4. S. Sudo (Ed.), Optical Fibre Amplifiers: Materials, Devices, and Applications. (Artech House Inc., Boston, 1997).

], this range is covered by emissions of the Er3+ and Tm3+ in GC shown Fig. 2 (a).

The excitation spectra for the 4I13/24I15/2 (measured at 1.505 µm) and the 3F43H6 (measured at 1.640 µm) emission bands of the Er3+ and Tm3+, respectively, are shown in Fig. 3 for the GC (a) and for its precursor glass (b). A very important result is seen in Fig. 3(a) that the excitation spectra are the same for these emission bands of the Er3+ and Tm3+ in GC. Moreover, the lifetimes of these two bands of the Er3+ and Tm3+, 8.8 and 9.6 ms, respectively, are also similar in GC (see Table). Therefore the entire band in GC between 1.5 to 1.7 µm behaves as a band of single dopant pointing out that it could be used as a single emission band for optical amplification/lasing in the extended telecommunication window.

Fig. 3. Excitation spectra for the emission bands of the Er3+, 4I13/24I15/2 transition at 1505 nm (thick line) and of the Tm3+, 3F43H6 transition at 1640 nm (thin line) in GC (a) and precursor glass (b).

Remarkably, such a good emission performance of the Er3+-Tm3+ couple, Fig. 2(a) can be achieved only in the case of GC, while in the precursor glass the lifetimes (1.1 ms for the Er3+ and 6.1 ms for the Tm3+, see Table) and excitation spectra, Fig. 3(b), of the Er3+ and Tm3+ differ substantially. The difference in excitation spectra, Fig. 3(b), is seen in particular at about 463 and 680 nm, where the absorption spectrum of the precursor glass is dominated by absorption bands of the Tm3+, the 1G43H6 and 3F33H6 transitions, respectively, Fig. 1. The difference in excitation spectra and substantially longer lifetime of the Tm3+ in the glass point out that energy transfer between co-dopants is suppressed in the precursor glass, while it is reinforced in the GC, as seen from Fig. 3(a), where the excitation spectra for Er3+ and Tm3+ are identical. Therefore, we conclude that a substantial shortening of distance between co-dopants takes place in the GC compared to the precursor glass, in agreement with [5

5. G. Dantelle, M. Mortier, D. Vivien, and G. Patriarche, “Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics,” Opt. Mater. 28, 638–642 (2006). [CrossRef]

,7

7. V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

,17

17. Y.H. Wang and J. Ohwaki, “New transparent vitroceramics codoped with Er3+ and Yb3+ for efficient frequency upconversion,” Appl. Phys. Lett. 63, 3268–3270 (1993). [CrossRef]

]. While in GC, the most of rare-earth dopants are trapped in nano-crystals, in the precursor glass, the dopants distribute homogeneously across the entire glass network.

An interesting implication can be drawn from the low temperature (77 K) emission spectra of GC presented in Fig. 2(b). Here we see that the energy transfer between Yb3+, Er3+ and Tm3+ co-dopants has been vanished even in case of GC, because individual pump of each of the dopants (in 980 nm absorption band for the Yb3+; 522 nm band for the Er3+; and 463 nm band for the Tm3+) results in emission mostly from the same co-dopant, which was pumped. The lifetimes for the Er3+ (6.8 ms) and Tm3+ (12.0 ms) also differ substantially at 77 K in case of GC (see Table). Therefore, we conclude that the energy transfer between Yb3+, Er3+ and Tm3+ co-dopants is quite suppressed at 77 K even in GC, and this indicates the importance of vibronic contribution to the energy transfer at the room temperature. We suggest that the phonon, which mediates the energy transfer between the co-dopants is a 140 cm-1 “ungerade” (asymmetric) vibration au [18

18. C. Görller-Walrand, K. Binnemans, and K.A. Gschneider Jr., and L. Eyring, ed. (North-Holland, Amsterdam, 1996). v.23, p.121.

] typical of PbF2 crystal ([19

19. A.V. Bazhenov, I.S. Smirnova, T.N. Fursova, M.Y. Maksimuk, A.B. Kulakov, and I.K. Bdikin, “Optical phonon spectra of PbF2 single crystals,” Phys. Sol. State 42, 41–50 (2000). [CrossRef]

] and refs therein). While this phonon vibration is well populated at room temperature (300 K=210 cm-1), it is almost completely frozen at 77 K (77 K=54 cm-1). A vibronic contribution of this “ungerade” phonon mode to the intensity of optical transition of rare-earth dopants in this GC host has been noted earlier, e.g. in [9

9. K. Driesen, V.K. Tikhomirov, C. Görller-Walrand, V.D. Rodríguez, and A.B. Seddon, “Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission,” Appl. Phys. Lett.88, art.073111 (2006). [CrossRef]

] for the case of the Ho3+. Other typical vibrations of PbF2 are higher than 210 cm-1 (i.e. a dominating symmetric vibration t2g at 240 cm-1) and could not substantially contribute to the energy transfer at room temperature. Also, the “ungerade” asymmetric vibration induces more efficiently a dipole-dipole interaction of Van der Waals type between the co-dopants, which allows an energy transfer between co-dopants, e.g. [12

12. F. Auzel “Upconversion and Anti-Stokes processes with f and d Ions in Solids,” Chem. Rev. 105, 139–173 (2004). [CrossRef]

] and refs therein.

Table. 1. Lifetime of the energy levels of the Er3+ and Tm3+ at room temperature and at 77 K, where indicated, in 3.5 mol% (Yb3+-Er3+-Tm3+) co-doped GC and precursor glass, and in single, 3.5 mol% Er3+ and Tm3+-doped GC and precursor glass.

table-icon
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The lifetimes of the 4I13/24I15/2 (1.55 µm) transition of the Er3+ and of the 3F43H6 (1.64 µm) transition of the Tm3+ in Yb3+-Er3+-Tm3+ co-doped and in Er3+ and Tm3+ single doped samples with similar doping level are compared in the table. A simple correlation between lifetimes of the Er3+ and Tm3+ in co-doped and single doped samples is absent indicating that it is the energy transfer between Yb3+, Er3+ and Tm3+ co-dopants, which defines lifetimes of the co-dopants in co-doped samples.

The Er3+ and Tm3+ co-dopants seem to play an important role in mutual depopulation of their higher energy levels. This has been confirmed by measurement of lifetimes of majority of the upper levels of the Er3+ and Tm3+ using time-resolved up-conversion luminescence spectroscopy. The lifetime of all levels was shorter that 70 µs. Apparently, the lifetimes of the feeding levels of the Er3+ (4I11/24I15/2, 0.98 µm transition) and Tm3+ (3H53H6, 1.2 µm transition) are also shorter than 70 µs, as seen from the Table. This has a positive impact on the population inversion of the lasing levels of the Er3+ (4I13/2) and Tm3+ (3F4).

4. Conclusion

Yb-Er-Tm co-doped GC has a potential for emission/light amplification devices in the tunable wavelength range from 1.5 to 1.7 µm. 9 ms lifetime of the lasing transitions of the Er3+ (4I13/24I15/2 transition) and the Tm3+ (3F43H6 transition), which overlap and cover the 1.5 to 1.7 µm range, and very short lifetime of their upper feeding levels, indicate that population inversion for those lasing levels may be achieved in GC. Short-length chip amplifier/lasers due to high doping levels of pump co-dopant Yb3+ and emitting co-dopants Er3+ and Tm3+, and high pump cross-section for the Yb3+, may be possible.

References and links

1.

G.C. Thomas, B.I. Shraiman, P.F. Glodis, and M.J. Stephen, “Towards the clarity limit in optical fibre,” Nature (London) 404, 262–264 (2000). [CrossRef]

2.

E. Desurvire, Erbium-doped Fibre Amplifiers: Materials, Devices and Applications. (Wiley, New York, 1994).

3.

P.C. Becker, N.A. Olsson, and J.R. Simpson, Erbium-doped Fibre Amplifiers: Fundamentals and Technology, (Academic, San Diego, 1999).

4.

S. Sudo (Ed.), Optical Fibre Amplifiers: Materials, Devices, and Applications. (Artech House Inc., Boston, 1997).

5.

G. Dantelle, M. Mortier, D. Vivien, and G. Patriarche, “Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics,” Opt. Mater. 28, 638–642 (2006). [CrossRef]

6.

A. Mori, Y. Ohishi, S. Sudo, A. Mori, T. Sakamoto, K. Kobayashi, K. Ishikano, K. Oikawa, K. Hoshino, T. Kanamori, Y. Ohishi, and H. Shimizu, “1.58 µm broad-band erbium-doped tellurite fibre amplifier,” J. Lightwave Technol. 20, 794–799 (2002). [CrossRef]

7.

V.K. Tikhomirov, D. Furniss, I.M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, “Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics,” Appl. Phys. Lett. 81, 1937–1939 (2002). [CrossRef]

8.

V. Rodriguez, V.K. Tikhomirov, J. Mendez-Ramos, and A.B. Seddon, “The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics,” Europhys. Lett. 69, 128–134 (2005). [CrossRef]

9.

K. Driesen, V.K. Tikhomirov, C. Görller-Walrand, V.D. Rodríguez, and A.B. Seddon, “Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission,” Appl. Phys. Lett.88, art.073111 (2006). [CrossRef]

10.

V.K. Tikhomirov, K. Driesen, and C. Görller-Walrand, “Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm,” Phys. Status Solidi (a) 204, 839–845 (2007). [CrossRef]

11.

J.F. Suyver, J. Grimm, M.K. van Veen, D. Biner, K.W. Krämer, and H.U. Güdel, “Upconversion spectroscopy and properties of NaYF4 doped with Er3+, Tm3+ and/or Yb3+,” J. Lumin. 117, 1–12 (2006). [CrossRef]

12.

F. Auzel “Upconversion and Anti-Stokes processes with f and d Ions in Solids,” Chem. Rev. 105, 139–173 (2004). [CrossRef]

13.

V.K. Tikhomirov, J. Koch, D. Wand, and B. Chichkov, “Fabrication of buried waveguides and nano-crystals in Er3+-doped oxyfluoride glass,” Phys. Status Solidi (a) 202, R73–R75 (2005). [CrossRef]

14.

S. Hull, “Superionics crystal structures and conduction processes,” Rep. Prog. Phys. 67, 1233–1314 (2004). [CrossRef]

15.

D.J.M. Bevan, J. Strähle, and O. Greis, “The crystal-structure of tveitite, an ordered yttrofluorite mineral,” J. Solid State Chem. 44, 75–81 (1982). [CrossRef]

16.

M. Mattarelli, V.K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G.C. Righini, L. Zampedri, and M. Ferrari, “Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties,” J. Non-Cryst. Sol. 345&346, 354–358 (2004). [CrossRef]

17.

Y.H. Wang and J. Ohwaki, “New transparent vitroceramics codoped with Er3+ and Yb3+ for efficient frequency upconversion,” Appl. Phys. Lett. 63, 3268–3270 (1993). [CrossRef]

18.

C. Görller-Walrand, K. Binnemans, and K.A. Gschneider Jr., and L. Eyring, ed. (North-Holland, Amsterdam, 1996). v.23, p.121.

19.

A.V. Bazhenov, I.S. Smirnova, T.N. Fursova, M.Y. Maksimuk, A.B. Kulakov, and I.K. Bdikin, “Optical phonon spectra of PbF2 single crystals,” Phys. Sol. State 42, 41–50 (2000). [CrossRef]

OCIS Codes
(160.2750) Materials : Glass and other amorphous materials
(160.5690) Materials : Rare-earth-doped materials
(250.5230) Optoelectronics : Photoluminescence

ToC Category:
Materials

History
Original Manuscript: April 23, 2007
Revised Manuscript: July 10, 2007
Manuscript Accepted: July 10, 2007
Published: July 17, 2007

Citation
V. K. Tikhomirov, K. Driesen, C. Görller-Walrand, and M. Mortier, "Broadband telecommunication wavelength emission in Yb3+-Er3+-Tm3+ co-doped nano-glassceramics," Opt. Express 15, 9535-9540 (2007)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-15-15-9535


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References

  1. G. C. Thomas, B. I. Shraiman, P. F. Glodis, and M. J. Stephen, "Towards the clarity limit in optical fibre," Nature (London) 404, 262-264 (2000). [CrossRef]
  2. E. Desurvire, Erbium-doped Fibre Amplifiers: Materials, Devices and Applications (Wiley, New York, 1994).
  3. P. C. Becker, N. A. Olsson, and J. R. Simpson, Erbium-doped Fibre Amplifiers: Fundamentals and Technology (Academic, San Diego, 1999).
  4. S. Sudo, ed., Optical Fibre Amplifiers: Materials, Devices, and Applications (Artech House Inc., Boston, 1997).
  5. G. Dantelle, M. Mortier, D. Vivien, G. Patriarche, "Influence of Ce3+-doping on the structure and luminescence of Er3+-doped transparent glass-ceramics," Opt. Mater. 28, 638-642 (2006). [CrossRef]
  6. A. Mori, Y. Ohishi, and S. Sudo, "Erbium-doped tellurite glass fibre laser and amplifier," Electron. Lett. 33, 863-865 (1997); A. Mori, T. Sakamoto, K. Kobayashi, K. Ishikano, K. Oikawa, K. Hoshino, T. Kanamori, Y. Ohishi, and H. Shimizu, "1.58 µm broad-band erbium-doped tellurite fibre amplifier," J. Lightwave Technol. 20, 794-799 (2002). [CrossRef]
  7. V. K. Tikhomirov, D. Furniss, I. M. Reaney, M. Beggiora, M. Ferrari, M. Montagna, and R. Rolli, "Fabrication and characterization of nanoscale, Er3+-doped, ultratransparent oxy-fluoride glass-ceramics," Appl. Phys. Lett. 81, 1937-1939 (2002). [CrossRef]
  8. V. Rodriguez, V. K. Tikhomirov, J. Mendez-Ramos, and A. B. Seddon, "The shape of the 1.55 µm emission band of the Er3+-dopant in oxyfluoride nano-scaled glass-ceramics," Europhys. Lett. 69, 128-134 (2005). [CrossRef]
  9. K. Driesen, V. K. Tikhomirov, C. Görller-Walrand, V. D. Rodríguez, A. B. Seddon, "Transparent Ho3+-doped nano-glass-ceramics for efficient infrared emission," Appl. Phys. Lett. 88, art.073111 (2006). [CrossRef]
  10. V. K. Tikhomirov, K. Driesen, C. Görller-Walrand, "Low energy robust host heavily doped with Dy3+ for emission at 1.3 to 1.4 µm," Phys. Status SolidiA 204, 839-845 (2007). [CrossRef]
  11. J. F. Suyver, J. Grimm, M. K. van Veen, D. Biner, K. W. Krämer, H. U. Güdel, "Upconversion spectroscopy and properties of NaYF4 doped with Er3+, Tm3+ and/or Yb3+," J. Lumin. 117, 1-12 (2006). [CrossRef]
  12. F. Auzel "Upconversion and Anti-Stokes processes with f and d Ions in Solids," Chem. Rev. 105, 139-173 (2004). [CrossRef]
  13. V. K. Tikhomirov, J. Koch, D. Wand, and B. Chichkov, "Fabrication of buried waveguides and nano-crystals in Er3+-doped oxyfluoride glass," Phys. Status SolidiA 202, R73-R75 (2005). [CrossRef]
  14. S. Hull, "Superionics crystal structures and conduction processes," Rep. Prog. Phys. 67, 1233-1314 (2004). [CrossRef]
  15. D. J. M. Bevan, J. Strähle, and O. Greis, "The crystal-structure of tveitite, an ordered yttrofluorite mineral," J. Solid State Chem. 44, 75-81 (1982). [CrossRef]
  16. M. Mattarelli, V. K. Tikhomirov, M. Montagna, E. Moser, A. Chiasera, S. Chaussedent, G. Nunzi Conti, S. Pelli, G. C. Righini, L. Zampedri, and M. Ferrari, "Tm3+-activated transparent oxy-fluoride glass-ceramics: structural and spectroscopic properties," J. Non-Cryst. Sol. 345&346, 354-358 (2004). [CrossRef]
  17. Y. H. Wang and J. Ohwaki, "New transparent vitroceramics codoped with Er3+ and Yb3+ for efficient frequency upconversion," Appl. Phys. Lett. 63, 3268-3270 (1993). [CrossRef]
  18. C. Görller-Walrand and K. Binnemans, "Rationalization of crystal field parametrization," in Handbook on the Physics and Chemistry of Rare Earths, K. A. Gschneider, Jr. and L. Eyring, ed., (North-Holland, Amsterdam, 1996). Vol. .23, p.121.
  19. A. V. Bazhenov, I. S. Smirnova, T. N. Fursova, M. Y. Maksimuk, A. B. Kulakov, and I. K. Bdikin, "Optical phonon spectra of PbF2 single crystals," Phys. Solid State 42, 41-50 (2000). [CrossRef]

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