The 1.53 mm spectroscopic properties and thermal stability
in Er
3 þ
/Ce
3 þ
codoped TeO
2
–WO
3
–Na
2
O–Nb
2
O
5
glasses
Shichao Zheng, Yaxun Zhou
n
, Dandan Yin, Xingchen Xu, Yawei Qi, Shengxi Peng
College of Information Science and Engineering, Ningbo University, Zhejiang 315211, China
article info
Article history:
Received 29 December 2012
Received in revised form
18 February 2013
Accepted 23 February 2013
Available online 1 March 2013
Keywords:
Tellurite-based glass
1.53
m
m band fluorescence
Energy transfer
Er
3þ
/Ce
3þ
codoping
abstract
Er
3þ
/Ce
3þ
codoped tellurite-based glasses with composition of TeO
2
–WO
3
–Na
2
O–Nb
2
O
5
were pr epared by high-temperature melt-quenching technique and a detailed study of the
1.53
m
m band spectroscopic properties and thermal stability was presented in this paper. The
absorption spectra, visible upconversion spectra, 1.53
m
m band fluorescence spectra, fluores-
cence lifetimes, Raman spectra, differential scanning calorimeter (DSC) and X-ray diffraction
(XRD) curves of glass samples were measured and investigated, together with the quantitative
calculations and analyses of Judd–Ofelt intensity parameters, stimulated emission and
absorption cross-sections, amplification quality factors, energy transfer rates and quantum
transition efficiencies. It was found that the prepared glass samples have good thermal
stability (T
g
4425 1C), large Judd–Ofelt intensity parameter (
O
6
40.80 10
20
cm
2
)and
bandwidth quality factor (
s
p
e
FWHM 4360 10
21
cm
2
nm) of Er
3þ
. With the increasing
of Ce
3þ
doped concentration, the visible upconversion emission decreased while the 1.53
m
m
band fluorescence intensity improved significantly due to the enhanced energy transfer of
Er
3þ
:
4
I
11/2
þCe
3þ
:
2
F
5/2
-Er
3þ
:
4
I
13/2
þCe
3þ
:
2
F
7/2
owing to the moderate phonon energy
(930 cm
1
) of glass host, which was beneficial in compensating for the existing energy
mismatch between the Er
3þ
:
4
I
11/2
-
4
I
13/2
emission and Ce
3þ
:
2
F
5/2
-
2
F
7/2
absorption transi-
tions. Compared with the Er
3þ
single-doped case, the 1.53
m
m band fluorescence intensity in
Er
3þ
/Ce
3þ
codoped glass sample could increase by about 30%. The results indicate that the
prepared tellurite-based glass with a suitable Er
3þ
/Ce
3þ
codoping concentration is an
excellent gain medium applied for broadband EDFA pumped with a 980 nm laser diode.
& 2013 Elsevier Ltd. All rights reserved.
1. Introduction
Due to the rapid increase of information capacity and
the need for flexible telecom networks, there exists
urgent demand for optical amplifiers with a wide and flat
gain spectrum to be used in the wavelength-division-
multiplexing (WDM) communication system [1–3]. One
method to realize this demand is the adoption of new
tellurite-based glass Er
3 þ
-doped fiber amplifier
(Te-EDFA), which possesses a broad fluorescence emission
and signal gain profile at 1.53
m
m band in the wavelength
range of 1520–1620 nm [4,5]. As a host material, tellurite
glass is well known to be good not only in mechanical
strength and chemical durability but also stable against
atmospheric moisture and corrosion [6,7]. In addition, it
has a low melting temperature and can be easily prepared
with conventional melt-quenching technique.
However, due to the relatively low phonon energy of
tellurite glass (750 cm
1
), the strong visible upconversion
emission resulting from the excited state absorption (ESA) of
pump level
4
I
11/2
is observed in Er
3þ
single-doped tellurite
glass under the 980 nm excitation [8]. As a consequence, the
rapid population of Er
3þ
ions at the fluorescence emitting
level
4
I
13/2
will be difficult, resulting in a weak 980 nm pump
efficiency and 1.53
m
m band fluorescence intensity. Also,
compared with the conventional silica glass, tellurite glass
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journal homepage: www.elsevier.com/locate/jqsrt
Journal of Quantitative Spectroscopy &
Radiative Transfer
0022-4073/$ - see front matter & 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jqsrt.2013.02.024
n
Corresponding author. Tel.: þ 86 574 87600319.
E-mail address: zhouyaxun@nbu.edu.cn (Y. Zhou).
Journal of Quantitative Spectroscopy & Radiative Transfer 120 (2013) 44–51