Tellurite glasses optical fibers became promising for optical amplifiers due to its high rare earth ions solubility and very large amplification bandwidth. Among several tellurite glasses the TeO2-WO 3-Na2O-Nb2O5 system show one of the largest bandwidth. Our previous characterization of lifetime using the Ω2, Ω4, Ω6, Judd-Ofelt parameters indicate a quantum efficiency maximum for 7500ppm Er3+ concentration. Therefore we decided to produce jointed Er3+ and Tm3+ single mode optical fibers with this glass system keeping the 7500ppm Er3+ concentration and varying the Tm3+ concentration from 2500ppm to 15000ppm. This single mode fiber was pumped by 120mW of the semiconductor laser at 790nm and we observed a flat ASE bandwidth from 1400 to 1570nm for the 5000ppm Tm3+ concentration.5723243247Jeong, H., Oh, K., Han, S.R., Morse, T.F., Broadband amplified spontaneous emission from an Er3+-Tm 3+ - Codoped silica fibar (2003) Opt. Lett., 28, pp. 161-163Reisfeld, R., Jorgensen, C.K., (1987) Handbook on the Physics and Chemistry of Rare Earths, 9, pp. 1-90. , K. A. Gschneidner, Jr. and L. Eyring (Eds.), Elsevier ScienceChen, C.Y., Petrin, R.R., Yeh, D.C., Sibley, W.A., Concentration-dependent energy-transfer processes in Er3+-and Tm3+ -doped heavy-metal fluoride (1989) Opt. Lett., 14, pp. 432-434Miniscalco, W.J., Quimby, R.S., General procedure for the analysis of Er3+ cross sections (1991) Opt. Lett, 16, pp. 258-26

Barbosa L.C.

Cesar C.L.

Chillcce E.F.

Osorio S.P.

Rodriguez E.

English

Repositorio da Producao Cientifica e Intelectual da Unicamp

  
Ultra large amplification bandwidth of Er3+ and Tm3+ at S and L band 
from TeO2-WO3-Na2O-Nb2O5 glass doped optical fibers 
 
E. F. Chillcce, S. P. Osorio, E. Rodriguez, C. L. Cesar and L. C. Barbosa∗ 
Universidade Estadual de Campinas; CEP 13083-970-Campinas-SP-Brazil 
CEPOF: http//www.ifi.unicamp.br/foton 
 
 
ABSTRACT 
 
Tellurite glasses optical fibers became promising for optical amplifiers due to its high rare earth ions solubility and very 
large amplification bandwidth. Among several tellurite glasses the TeO2-WO3-Na2O-Nb2O5 system show one of the 
largest bandwidth. Our previous characterization of lifetime using the Ω2, Ω4, Ω6, Judd-Ofelt parameters indicate a 
quantum efficiency maximum for 7500ppm Er3+ concentration. Therefore we decided to produce jointed Er3+ and Tm3+ 
single mode optical fibers with this glass system keeping the 7500ppm Er3+ concentration and varying the Tm3+ 
concentration from 2500ppm to 15000ppm. This single mode fiber was pumped by 120mW of the semiconductor laser at 
790nm and we observed a flat ASE bandwidth from 1400 to 1570nm for the 5000ppm Tm3+ concentration. 
 
Keywords: Broadband emission, tellurite fiber, energy transfer process  
 
1. INTRODUCTION 
 
Tungsten- tellurite glass matrices are ideal hosts for the fabrication of the large bandwidth Er3+-Tm3+-co-doped fiber 
amplifiers, due to the modern Wavelength Division Multiplexing (WDM) optical communication systems demand the 
broadest continuous optical amplifiers as possible. The 45 nm bandwidth of Er3+ silica doped optical fibers at the C-band 
(1530-1565 nm) is insufficient for greatest speed of information transmission. Recently, Jeong et al demonstrate an Er3+- 
Tm3+ co-doped 20m long silica fiber amplified spontaneous emission (ASE) with bandwidth over 90nm (1460-1550 nm), 
without any external filters, when the fiber is pumped at 980 nm [1]. Tellurite glasses, however, known for the 
enhancement of the amplification bandwidth, should be a better host than silica. In co-doped systems the most important 
processes are energy transfer (ET) that can either help the amplification or decrease its efficiency. The energy transfer 
processes between the 4I13/2 Er3+ and 3F4 Tm3+ levels, which are responsible for an ASE intensity reduction 1550nm 
wavelength around.  
 
 
2. EXPERIMENTAL 
 
For the Optical Fibers fabrication we used the tellurite glass matrix 70TeO2 - 19WO3 -7Na2O - 4Nb2O5 (%mol) 
as the base glass for the core and the clad. To increase the core refractive index, and, consequently, the fiber Numerical 
Aperture (NA), we increased the Nb2O5 core content by 80000 ppm. The pre-form was made by the rod-in-tube method, 
using a 7 mm external diameter basic glass for the clad and 0.5 mm Er3+/Er3+-Tm3+ doped glass for the core. Good 
quality optical fibers were obtained after drawn at the 540 -550 oC temperature range in a Heathway tower with 3.6 
m/min draw speed. The 125 µm external diameter fiber obtained matches the core size of commercial silica fibers with 
10 µm core diameter to assure good light coupling. The ASE measurements was made using a Ti:sapphire cw laser 
(Spectra Physics model 3900S), which is coupled to the tellurite fiber core through of the objective lens at one fiber end 
while the luminescence was collected on the opposite by another identical objective lens. To avoid the 790 nm second 
order at 1580 nm we used a Schott RG1000 filter to cut-off all the pump light before the Optical Spectrum Analyzer 
(OSA) (Agilent HP 86145B). A third objective lens after the filter couples the light into another silica fiber directly 
connected to the OSA. The ASE intensity measurements were realized with 5nm wavelength resolution, and –50dBm 
reference level in the OSA. 
                                               
∗
 Corresponding author: barbosa@ifi.unicamp.br 
Optical Components and Materials II, edited by Shibin Jiang, Michel J. F. Digonnet,
Proceedings of SPIE Vol. 5723 (SPIE, Bellingham, WA, 2005)
0277-786X/05/$15 · doi: 10.1117/12.588423
243
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3. RESULTS AND DISCUSSIONS 
 
The both luminescence spectra showed in figure 1correspond to emission transitions of Er3+-Tm3+ -co-doped tellurite 
fiber. The luminescence intensity showed in figure 1-a was obtained with an Ocean Optics USB 2000 spectrophotometer 
in VIS-IR spectral range, while the luminescence intensity in figure 1-b was obtained with an OSA in IR spectral range. 
          
500 600 700 800 900
0
1
2
3
4
2H11/2−>
4I15/2 
4S3/2−>
4I15/2 
4F9/2−>
4I15/2 
3H4−>
3H6 
4S3/2−>
4I13/2 
 
 
Lu
m
in
es
c
en
ce
 
(a.
u
.
)
Wavelength (nm)(a)
 
800 1000 1200 1400 1600
-90
-85
-80
-75
-70
-65
-60
Pump 4I11/2−>
4I15/2
4F9/2−>
4I13/2
4S3/2−>
4I11/2
 
 
Lu
m
in
e
s
c
e
n
c
e
 (a
.
u
.
)
Wavelength (nm)(b)
 
  Fig. 1 Luminescence spectra in (a)VIS-IR  and (b) IR spectral range for a 7500ppm Er2O3-5000ppm Tm2O3-co-doped tellurite fiber.  
 
In both luminescence spectra there are eleven emission transitions in all, of these, tree transitions are not were named due 
to that these are overlapped in one band only, and these transitions are 3F4→ 3H6, 3H4→3F4, and 4I13/2→4I15/2. Of the same 
form tree transitions correspond to intermediate excited levels transitions, and these transitions are 4S3/2→ 4I11/2, 
4F9/2→4I13/2, and 4S3/2→4I13/2. From these results, its possible construct an Er3+-Tm3+-ions energy level diagram that 
shows all the important transitions between ground and excited levels, as well as energy transfer processes for an Er3+-
Tm3+-codoped tellurite fiber. In the figure 2 we showed all important mechanism based in absorption and emission 
processes. 
 
 
0,0
0,4
0,8
1,2
1,6
2,0
2,4
2,8
1700
1550
1460
790
ET3
 
 
790
 
ET1
ET2
 
 
 
Er3+Tm3+
1G4
3F23F33H4
3H5
3F4
3H6
(4F5/2 , 4F3/2)
4F7/22H11/24S3/2
4F9/2
4I9/2
 
4I11/2
4I13/2
4I15/2
En
er
gy
(eV
)
 
Fig. 2 Energy levels diagram for Er3+ and Tm3+ ions showing absorption, emission, and energy transfer processes. Gray arrows 
represent ground state absorption and excited state absorption. 
 
 
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The 1550 nm around transitions is very important in the optical communication due to that this band represent the optical 
communications window in silica fiber based. All mechanism and processes treated in front will be related to 1550nm 
transitions around. When the tellurite fibers are doped with Er3+ and Tm3+ ions, is known that exist an inherent energy 
transfer processes between ER3+-4I13/2 and Tm3+- 3F4 levels that play an important role in amplification processes. We 
observe that for large Tm3+ concentration in co-doped systems, the energy transfer between 4I13/2 Er3+- 3F4 Tm3+ levels is 
very efficient and as consequence the ASE power 1550nm around decrease. For small Tm3+ concentration in co-doped 
systems, the energy transfer between (Er3+) 4I13/2 - (Tm3+) 3F4 levels is not efficient and as consequence the ASE power 
1550nm around increase as well as 3H4→3F4 transition is very predominant. Figure 3 show the ASE intensity spectra for 
(7500ppm) Er3+-doped tellurite fiber and (7500ppm) Er3+- (5000ppm) Tm3+ -co-doped tellrurite concentrations. 
Pumping with 790 nm we only observed the 4I13/2 →4I15/2 transition for Er3+-only doped tellurite fiber, while all the 
4I13/2→ 4I15/2, 3H4→ 3F4 and 3F4→ 3H6 transitions are present in the Er3+-Tm3+ co-doped tellurite fibers. In the Er3+-Tm3+ 
co-doped tellurite fiber, the 3H4→ 3F4 transition appear in the left side of the 4I13/2→ 4I15/2 transition, and the 3F4→ 3H6 
transitions appear in the right side of the 4I13/2→ 4I15/2 transition. The bandwidth, measured at –3dB points, in (7500ppm) 
Er3+-doped tellurite fiber is 74nm, while in (7500ppm) Er3+- (5000ppm) Tm3+-co-doped tellurite fiber is 187nm. Figure 4 
show the ASE intensity spectra for two different Tm3+ concentration, and in this figure we observed that the ASE 
intensity decrease for a higher Tm3+ concentration. This fact is due to the separation between Er3+-donor and Tm3+-
acceptor ions diminish when the Tm3+ concentration increase. 
 
 
1300 1400 1500 1600
-90
-85
-80
-75
-70
-65
-60
(a)
(b)
 
 
AS
E 
Po
w
er
 
(dB
m
)
Wavelength (nm)
 
1300 1400 1500 1600 1700
-90
-85
-80
-75
-70
-65
-60
 
 
A
SE
 
po
w
er
 
(d
B
m
)
Wavelength (nm)
Tm2O3 Content(ppm)
 5000
 7500
 
Fig. 3 The fibers characterized have 15cm length. The (a)-curve 
corresponds to Er3+-doped tellurite fiber and (b)-curve 
corresponds to Er3+-Tm3+ -co-doped tellurite fiber. 
 
Fig.  4 The fibers characterized have 15cm length. The ASE 
power decreases due to increase of Tm3+ concentration. 
 
 
 
The separation between Er3+-donor and Tm3+-acceptor is possible to calculating from energy transfer transition 
probabilities ( TmErTEW − ). To perform the TmErTEW − calculated as a function of Tm3+ content we co-doped the same 
7500ppm wt% Er2O3 doped tellurite glass matrix with Tm2O3 concentrations varying from 2500ppm up to 15000ppm 
wt%. With the previously calculated lifetime experimentally and calculated lifetime trough Judd-Ofelt parameters, we 
can calculate the TmErTEW
−
 using the expression:  
Er
NRe
TmEr
TE
WW −η−τ= −− )(11
 
 Here, /e c R eWη τ τ τ= =  represents the quantum efficiency and Rc W=−1τ  is calculated by the Judd-Ofelt parameters, 
and ErNRW  represents all nonradiative transition probabilities for Erbium only doped glasses. Figure 5 shows the results 
obtained. The lifetime represented at the left axis decreases as the Tm3+ concentration increases, and the ET1 process 
becomes more efficient.  
Proc. of SPIE Vol. 5723     245
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0.0 0.5 1.0 1.5 2.0 2.5
0 3 7 9 12 16
0
1
2
3
4
5
6
Tm2O3 Content(1000 ppm)
 
Tm 3+ Content (1020 ions cm- 3)
Li
fe
tim
e 
M
ea
su
re
d 
(m
s)
0
300
600
900
1200
1500
W
TE
1 
(s-
1 )
 
1400 1600 1800 2000
0
1
2
3
4
5
6
7
Tm3+ Absorption
 
 
Er3+ Emission
Cr
os
s 
Se
ct
io
n
 
(10
-
21
 
cm
2 )
Wavelength (nm)
 
Fig 5 Lifetime experimental and energy transfer transition 
probabilities. 
 
Fig. 6 The Tm3+ -absorption and Er3+ -emission crosses sections 
in the tellurite glass. 
 
 
Using the results obtained before, and the overlap of the Tm3+ Absorption and Er3+ emission crosses sections showed in 
the figure 6, its possible to calculating the donor-acceptor separations considering the dipole-dipole interactions for dilute 
systems [2]. Using the Forster-Dexter energy transfer model for dipole-dipole interactions [3], should be calculated the 
transitions probability rate between 4I13/2 level of Er3+-ion and 3F4 level of the Tm3+- ion. The critical interaction distance 
(R0) defined in [3] is calculated in this case, and the result obtained was nearly 4nm. In heavy-metal fluoride glass the 
result obtained by Chen et al was 1.48nm. The discrepancy of both results should be due to materials host principally. 
The calculus of the emission cross section was found using the expression guided by Miniscalco et al [4]. The donor-
acceptor separation is finally calculated, from previous calculus, for each Tm3+ concentration in the co-doped system. 
The result is showed in the figure 7 and is possible to observing that the behavior of the donor-acceptor separation 
decrease while the Tm3+ concentration increase. This result coherent, explain the fact that the energy transfer process is 
very efficient when the Tm3+ concentration is very high in co-doped systems. 
 
 
0.0 0.5 1.0 1.5 2.0 2.5
1.29
1.32
1.35
1.38
1.41
1.44
 
 
 
R d
a 
(n
m
)
Tm3+ Content (10 20 ions/cm3)
 
Fig. 7 Donor-acceptor separation (Rda) as function of the Tm3+ concentration in a co-doped system. 
 
 
 
246     Proc. of SPIE Vol. 5723
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4. CONCLUSION 
 
In conclusion, we obtained 187nm ASE bandwidth at -3dB points using Er3+- Tm3+ co-doped tellurite optical fibers 
pumping at 790 nm. Luminescence intensity and lifetime measurements show that the ET1 process between 4I13/2 to 3F4 
levels in Er3+- Tm3+ co-doped fiber is the mechanism responsible for the ASE decreasing as the Tm3+ concentration pass 
5000 ppm (%wt) and that we should avoid it in order to keep the ultra large amplification bandwidth at higher 
concentrations and gain. The behavior of the separation distance between Er3+ and Tm3+ ions in function of the Tm3+ 
concentration, indicate that the energy transfer probability increase for higher Tm3+ concentration in the Er3+-Tm3+ co-
doped tellurite fiber. 
 
5. ACKNOWLEDGMENTS 
 
Authors acknowledge CNPq, FAPESP, and CEPOF (Brazilian agencies) for financial support, as well as to Julio C. 
Guedes, Roberto B. Borges, Jose C. Fenizzi, and Ademir C. Camilo by technical support.  
 
6. REFERENCES 
 
[1] H. Jeong, K. Oh, S. R. Han, T.F. Morse, “Broadband amplified spontaneous emission from an Er3+-Tm3+ -
codoped silica fibar”, Opt. Lett. 28, 2003, pp 161-163 
[2] R. Reisfeld, C. K. Jorgensen, in: K. A. Gschneidner, Jr. and L. Eyring (Eds.), “ Handbook on the physics and 
chemistry of rare earths”, vol. 9, pp. 1- 90, Elsevier Science (1987) 
[3] C. Y. Chen, R. R. Petrin, D. C. Yeh, W. A. Sibley, “Concentration-Dependent energy-Transfer processes in 
Er3+-and Tm3+ -doped heavy-metal fluoride glass”, Opt. Lett. 14, 1989, pp 432-434  
[4] W. J. Miniscalco, R.S. Quimby, “General procedure for the analysis of Er3+ cross sections”, Opt. Lett,  16, 1991, 
pp 258-260. 
Proc. of SPIE Vol. 5723     247
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Ultra Large Amplification Bandwidth Of Er3+ And Tm3+ At S And L Band From Teo2-wo3-na2o-nb 2o5 Glass Doped Optical Fibers

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Ultra Large Amplification Bandwidth Of Er3+ And Tm3+ At S And L Band From Teo2-wo3-na2o-nb 2o5 Glass Doped Optical Fibers

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