Thermal stability and 2.7 μm spectroscopic properties in Er3+ doped tellurite glasses

Thermal stability and 2.7 μm spectroscopic properties in Er3+ doped tellurite glasses

Accepted Manuscript Thermal stability and 2.7 μm spectroscopic properties in Er 3+ doped tellurite glasses Ying Tian, Bingpeng Li, Rong Chen, Jiena...

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Accepted Manuscript Thermal stability and 2.7 μm spectroscopic properties in Er

3+

doped tellurite glasses

Ying Tian, Bingpeng Li, Rong Chen, Jienan Xia, Xufeng Jing, Junjie Zhang, Shiqing Xu PII:

S1293-2558(16)30516-7

DOI:

10.1016/j.solidstatesciences.2016.07.012

Reference:

SSSCIE 5353

To appear in:

Solid State Sciences

Received Date: 9 December 2015 Revised Date:

28 July 2016

Accepted Date: 31 July 2016

Please cite this article as: Y. Tian, B. Li, R. Chen, J. Xia, X. Jing, J. Zhang, S. Xu, Thermal stability 3+ and 2.7 μm spectroscopic properties in Er doped tellurite glasses, Solid State Sciences (2016), doi: 10.1016/j.solidstatesciences.2016.07.012. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Thermal stability and 2.7 µm spectroscopic properties in Er3+ doped tellurite glasses Ying Tiana, Bingpeng Lia,∗, Rong Chena, Jienan Xiab, Xufeng Jingc, Junjie Zhanga,

a

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Shiqing Xua,∗ College of Materials Science and Engineering, China Jiliang University, Hangzhou

310018, PR China b

Institute of Optoelectronic Technology, China Jiliang University, Hangzhou 310018,

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c

LiangXin College, China Jiliang University, Hangzhou 310018, PR China

PR China

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Abstract

In present paper, the thermal stability and 2.7 µm spectroscopic properties in Er3+ doped tellurite glasses have been investigated by 980 nm laser diode pumping. Thermal analysis indicates that GeO2 modified tellurite glass has better thermal stability and anti-crystallization ability. Judd-Ofelt intensity parameters are calculated

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and discussed to examine the covalency characteristics based on absorption spectra. The 2.7 µm fluorescence is obtained and the lifetime can reach 124±1 µs with the quantum efficiency of 61.5% in prepared samples. Moreover, higher effective emission bandwidth (136.67 nm), emission cross sections (12.75×10-21 cm2) and

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radiative transition probability (95.66s-1) at 2.7 µm are achieved. In addition, upconversion and near-infrared emission spectra are measured to elucidate energy

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transfer mechanism of Er3+. The results suggest that the present tellurite glass modified by GeO2 might have promising applications in mid-infrared fiber lasers. Keywords: 2.7µm fluorescence; lifetime; Er3+ doped tellurite glass; energy transfer. 1 Introduction

Mid-infrared fiber laser operating at ~3µm region has special advantages over other lasers in military, medical treatment, optical communication, environment monitoring, etc.[1-3]. At present, it can be obtained by near-infrared diode-pumped rare earth ions *

Corresponding author. Tel.: +86 571 8683 5781; fax: +86 571 2888 9527 E-mail address: [email protected] (Y. Tian),[email protected] (S. Xu) 1

ACCEPTED MANUSCRIPT doped glass or fiber. So far, mid-infrared luminescent ions mainly include Er3+, Ho3+ and Dy3+ ions[4-6]. Er3+ ion is widely investigated due to its absorption transitions of 4

I15/2→4I9/2 and 4I15/2→4I11/2, which can be pumped by commercial 808 nm and 980

nm laser diodes.

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In this case, CW 3µm fiber laser was achieved in a Er3+ doped ZBLAN fiber with output power of 24W in liquid-cooled condition according to S. Tokita et al.[7]. However, at high laser pump power, ZBLAN fiber is easy to damage due to its poor thermal stability and mechanical strength. Therefore, an appropriate glass matrix is

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needed to get the higher and more stable 3µm laser output. Based on this idea, heavy metal oxide glasses have been developed for mid-infrared fiber laser such as

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germanate glass[8], tellurite glass[9] and bismuthate glass[10].

Among all kinds of glasses, tellurite glass has the merits of lower melting point, lower phonon energy and higher refractive index compared with germanate glass[11]. Its low phonon energy is beneficial for reducing non-radiative relaxation probability while the high index of refraction benefits stimulated emission cross section of rare

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earth ions in glass host[11]. On the other hand, the final color of bismuthate glass strongly depends on the crucible type and the melting conditions. Besides, the darkening process of the bismuthate glass is a second open question[12]. Thus,

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tellurite glass becomes a natural candidate for mid-infrared laser. So far, some reports on ~3µm fluorescence have occurred in tellurite glasses. For instance, Y. Ma, et al. investigated 2.7µm spectroscopic properties of Er3+ doped zinc- and tungsten-

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modified tellurite glasses[4]. Y. Guo, et al. reported enhanced 2.7µm emissions and energy transfer mechanism in Er3+ -doped sodium tellurite glasses sensitized by Nd3+[13]. However, the measured lifetime at 2.7µm was hardly reported in Er3+ doped tellurite glasses. It is well known that mid-infrared radiative lifetime and quantum efficiency are important parameters to accurately estimate spectroscopic performances. Therefore, it is necessary to further investigate spectroscopic properties at 2.7µm and energy transfer mechanism in Er3+ doped tellurite glasses. Among all kinds of tellurite glasses, TeO2-ZnO-Na2O system is a promising candidate due to its low melting temperature (~850 °C) and good glass forming 2

ACCEPTED MANUSCRIPT ability[14, 15]. Unfortunately, its thermal stability is poor, which is not beneficial for fiber drawing while the low glass transition temperature limits its laser applications at high pumping power[16]. According to previous reports, GeO2 component can improve the thermal stability of tellurite glasses[11]. However, the investigations on

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mid-infrared spectroscopic properties of GeO2 modified tellurite glasses have not been published.

In this paper, the thermal stability, 2.7µm spectroscopic properties and energy transfer mechanism in GeO2 modified tellurite glasses have been systematically

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investigated to demonstrate the future applications in mid-infrared lasers. 2 Experimental

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Tellurite glasses with the following molar compositions (mol %): 69TeO2-20ZnO10Na2CO3-1Er2O3(TZN), 69TeO2-20ZnO-5Na2CO3-5GeO2-1Er2O3 (TZNG) were prepared by the melting-quenching method. High-purity raw materials of TeO2 (99.99%), ZnO (99%), Na2CO3 (99 %), Er2O3 (99.99%), and GeO2 (99.999%) powders were used. Well-mixed 20g batches of the samples were placed in a high for 30min. Then the melts were cast on a

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purity Al2O3 crucible and melted at 850

preheated steel plate and annealed for 3 hours at 10 °C below the glass transition temperature, and finally they were cooled down to room temperature. The annealed

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samples were cut and polished to the size of 10 mm×10 mm×1 mm for the optical property measurements.

The sample densities were measured by means of the Archimedes principle using

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distilled water as immersion liquid and the refractive index of samples were carried out by the prism minimum deviation method. The DSC curves were measured by NETZSCH DTA 404 PC at the heating rate of 10 K/min with maximum error of ± 5°C.

Absorption

spectra

were

recorded

with

a

UV/VIS/NIR

spectrophotometer(JASCO V-570UV/VIS) in the range of 340-3300nm. The emission spectra (2550-2950 nm, 1500-1700 nm and 500-700 nm) were measured with a FLS980 (Edingburg Co., England) spectrometer pumped by a 980 nm InGaAs laser diode (LD). All the measurements were performed at room temperature. 3 Results and discussion 3

ACCEPTED MANUSCRIPT 3.1 Thermal stability Fig.1 shows DSC curves of prepared tellurite glasses with the heating rate of 10 K/min. It can be seen that the addition of GeO2 make the top crystallization peak temperature (Tp) higher compared with the sample without GeO2, indicating the

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restriction of crystallization tendency with the introduction of GeO2. To clearly evaluate the thermal stability of tellurite glasses, the characteristic temperatures such as glass transition temperature (Tg), Tp and onset crystallization temperature (Tx) are determined from Fig.1 and shown in Table 1.

C for GeO2 modified

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It can be seen from Table 1 that the Tg can reach 335

tellurite glass, higher than that of ZBLAN glass (269°C)[17]. Higher Tg can resist

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thermal damage of the glass caused by high power laser[8]. Thus, the prepared samples have good thermal stability to resist thermal damage at high power laser compared to the hosts listed in Table 1[8,17-19]. In order to draw fiber, excellent anti-crystallization ability of tellurite glass is required. In general, the glass forming factor ∆T (= Tx- Tg) is used to roughly evaluate anti-crystallization ability[20]. The

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bigger ∆T indicates the more stability to restrain crystallization for glasses and a wide working range of temperature during fiber drawing. It is found from Table 1 that ∆T values for both samples are above 130°C. They are much higher than that of ZBLAN

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glass (67°C) and are a little larger than those of germanate glass (129°C) and tellurite glass (123°C). Moreover, GeO2 modified tellurite glass has higher ∆T (141°C) compared with that without GeO2 (135°C). It is indicated that the prepared samples

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can facilitate the fiber drawing. To evaluate thermal stability of anticrystallization more accurately, the parameter S,

which is proposed by Saad and Poulain[21], has been utilized as follows

S =

∆T × (T p − Tx )

(1)

Tg The S reflects the resistance to crystallization after the formation of the glass. (Tp-Tx) is related to the rate of devitrification transformation of the glassy phases. Besides, the larger value of (Tx-Tg) delays the nucleation process. It is calculated that the S value of GeO2 modified tellurite glass is much higher than those of other glasses as shown 4

ACCEPTED MANUSCRIPT in Table 1. It is suggested that GeO2 modified tellurite glass is more desirable to achieve a large working range during fiber drawing and is a potential candidate for mid-infrared fiber laser. 3.2 Absorption spectra and radiative properties

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Absorption spectra of Er3+ doped tellurite glasses in the wavelength range from 340 to 3300 nm are measured and shown in Fig. 2. For both samples, the absorption spectra mainly consists of seven absorption bands centered at 1530, 976, 799, 653, 545, 523 and 489nm, corresponding to transitions from the 4I15/2 ground state to

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excited states 4I13/2, 4I11/2, 4I9/2, 4F9/2, 4S3/2, 2H11/2 and 4F7/2, respectively. In addition, broad absorption bands at ~3µm can also be observed and ascribed to OH- vibrations.

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It can be seen that the positions and shape of each peak in present samples are similar to those of other samples [22-24]. The divergence of intensity is due to the difference of ligand field around Er3+ ions. Moreover, it’s easy to see that the absorption peak in 523nm is much higher than others, corresponding to

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I15/2→2H11/2 transition.

According to the literature, this transition is very sensitive to the tiny changes of local

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coordination environment in Er3+, which is called as hypersensitive transition (HST)[12]. The intensity of HST improves a lot with the addition of GeO2 into tellurite glass. It is shown that the glassy structure changes. In order to understand the

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change of glassy structure, Judd-Ofelt intensity parameters (Ω2,4,6) are calculated based on absorption spectra and Judd-Ofelt theory[25, 26]. Judd-Ofelt theory is always used to analyze the spectral parameters of different

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glass hosts doping with rare earth ions[27, 28]. Table 2 lists the Ωt (t=2, 4, 6) parameters in present tellurite glasses. The obtained root mean square deviations (δr.m.s) are as low as 0.5×10-6 and 0.64×10-6, respectively. It indicates the reliable results in the calculation process. It is found that the Ω2 in GeO2 modified tellurite glass is higher than that without GeO2 and higher than those of other samples as shown in Table 2[18,29-31]. It is reported that Ω2 is closely related to the glassy structure (such as the symmetry and ordering of ligand) and is sensitive to the changes of glass compositions[32]. The higher Ω2 value means the higher covalency and asymmetry between Er3+ and ligand environment of glass host. Thus, the GeO2 modified tellurite 5

ACCEPTED MANUSCRIPT glass possesses higher covalency between Er3+ and ligand environment of glass host. According to the J-O parameters, the radiative transition probabilities (Arad, s-1), fluorescence branching ratios (β, %) and radiative lifetimes (τrad, ms) of Er3+ doped tellurite glasses are calculated which is displayed in Table 3. It can be seen that the

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Arad for 4I11/2→4I13/2 transition is as high as 95.66 s-1 in GeO2 modified sample, which is evidently higher than that without GeO2 (87.13 s-1). It is also larger than those of fluoride (20.3 s-1)[17] and germanate glass (36.45s-1)[33]. Higher radiative transition probability is helpful to achieve better laser action [34, 35]. Therefore, tellurite glass

3.3 Fluorescence spectra and lifetime at 2.7 µm

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modified by GeO2 is a potential mid-infrared laser material.

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Fig.3 shows the mid-infrared fluorescence spectra in Er3+ doped tellurite glasses pumped by a 980 nm LD. One can observe emission peaks at 2.7µm, which correspond to Er3+:4I11/2→4I13/2 transition. The introduction of GeO2 weakens the 2.7µm emissions. This phenomenon can be explained that the addition of GeO2 with larger phonon energy (~900 cm-1) enhances multi-phonon relaxation rate at 2.7µm

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emissions in tellurite glass [36, 37]. To further estimate 2.7µm emission properties, the decay curve monitored at 2.7µm is measured in GeO2 modified tellurite glass excited at 531 nm wavelength as shown in the inset of Fig.3. The measured lifetime at

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2.7µm is 124±1 µs by single exponential fitting process. It is lower than that of water-free fluorotellurite glasses (1.07~1.93 ms)[38]. The smaller lifetime is mainly due to the quenching action of OH- groups[38].

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The quantum efficiency (η) at 2.7 µm can be determined by[39]

η =

τm τR

(2)

It is calculated that the η is as high as 61.5%, suggesting that GeO2 modified tellurite glass is a promising candidate for mid-infrared applications. 3.4 Emission cross section and gain coefficient The emission cross section is another important parameter to evaluate the emission ability of luminescent center. The absorption and emission cross sections can be calculated by Füchtbauer-Ladenburg formula[40] and McCumber theory as 6

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σ em (λ ) =

λ4 Arad λI (λ ) × 2 8πcn ∫ λI (λ )dλ

Zl hc exp[ Zu kT

 1 1  − ] λ  λZL

(4)

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σem(λ ) = σ abs(λ )

(3)

where λ is the center wavelength, Arad is the radiative transition probability, I(λ) is the intensity of fluorescence spectra, n and c are the refractive index of glass host and the speed of light, Zl and Zu are partition functions of the lower and upper manifolds,

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respectively. Fig.4(a) gives the mid-infrared absorption and emission cross sections in Er3+ doped tellurite glass modified by GeO2. The maximum emission cross sections of

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present samples are listed in Table 4. It can be found that the maximum absorption (σabs) and emission cross sections (σem) are 11.17×10-21 cm2 and 12.75×10-21 cm2, respectively. The σem at 2.7 µm is larger than that without GeO2. It is also higher than those of ZBLAY glass (8.98×10-21 cm2)[12] and PbO-Bi2O3-Ga2O3 glass (6.50×10-21 cm2)[42]. The high σem is beneficial for achieving the good laser action.

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As is indicated in Fig.4 (a), the 2.7 µm emission peak of Er3+ ions in glasses is asymmetric. Therefore, to choose the effective emission bandwidth (∆λeff) is more reasonable other than the full width at half maximum (FWHM). The effective emission bandwidth (∆λeff) can be determined from[38]

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∆λeff =

∫ σ em(λ )dλ

σp

(5)

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where σp is the peak emission cross section. The calculated ∆λeff of present samples are also summarized in Table 4. It is found that the ∆λeff can reach 147.30 nm, which is larger than that of ZBLAY glass (96.70 nm)[12] and comparable to that of PbO-Bi2O3 -Ga2O3 glass (151.00 nm)[42]. It is well known that large ∆λeff (147.30 nm) is beneficial for data transmission as more as possible. Furthermore, the gain bandwidth (∆λeff×σepeak) of GeO2 modified tellurite glass can reach as high as 1742.54×10-28cm3, which is much higher than those of TZN (1582.00×10-28cm3), ZBLAY (868.37×10-28cm3)[12] and PbO-Bi2O3-Ga2O3 glass (981.50×10-28cm3)[42]. Results indicate that GeO2 modified tellurite glass might be a promising mid-infrared 7

ACCEPTED MANUSCRIPT laser material. To have a further understanding of the material’s laser properties, mid-infrared gain coefficient of GeO2 modified tellurite glass is determined as shown in Fig 4(b). The room temperature gain coefficient can be simply estimated by[43] G (λ , P) = N [ Pσ em (λ ) − (1 − P )σ abs (λ )]

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(6)

where P is the population inversion ratio determined by the ratio between the population of Er3+: 4I11/2 level and the total Er3+ ion concentration. It can be observed that the net gain can be obtained when the population inversion ratio is above 0.5. In

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addition, a flat gain bandwidth in the range of 2700-2900 nm could be obtained for population inversion above 50%, which might give a useful guide to design

3.5 Energy transfer mechanism

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broadband amplifier operating at 2.7 µm.

In order to understand mid-infrared luminescent mechanism, upconversion and near-infrared emission spectra are measured and shown in Fig.5 (a) and (b). It can be seen from Fig.5 (a) that three emission bands at 522 nm, 544nm and 660 nm,

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respectively occur in both samples, which correspond to Er3+:

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H11/2→4I15/2,

S3/2→4I15/2 and 4F9/2→4I15/2 transitions. Moreover, the intensities of three emission

bands all become weaker with the introduction of GeO2. From Fig.5 (b), one can see

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an emission peak at 1.55 µm due to the 4I13/2→4I15/2 transition. Moreover, the 1.55µm emission intensity in modified tellurite glass is weaker compared with that without

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GeO2, which can be attributed to high phonon energy of GeO2 in GeO2 modified tellurite glass.

Fig.6 displays the energy level diagram and energy transfer sketches of Er3+

pumped by a 980 nm LD. Firstly, ions on the Er3+: 4I15/2 level is excited to the 4I11/2 state by ground state absorption (GSA) when radiated by 980 nm LD. On one hand, the 4I11/2→4I13/2 transition together with 2.7 µm emission takes place because of radiative relaxation process. In addition, ions in 4I13/2 level can decay radiatively to ground level along with 1.53 µm emissions. On the other hand, excited state absorption (ESA1:4I11/2+a photon→4F7/2) and energy transfer upconversion processes 8

ACCEPTED MANUSCRIPT (ETU1): 4I11/2+4I11/2→4F7/2+4I15/2 making ions in 4F7/2 level populated[44]. According to the non-radiative relaxation processes (NR), ions in 4F7/2 state depopulated to 2H11/2, 4

S3/2, and 4F9/2 levels. Thus, 522 nm, 544nm and 660 nm light emissions happen via

Er3+: 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2 transitions. Besides, ions in 4I13/2 state

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might undergo the excited state absorption (ESA2) process: 4I13/2+a photon→ 4F9/2, which is beneficial for 660 nm emissions. Furthermore, ETU2 (4I13/2+4I13/2→ 4

I9/2+4I15/2) process may take place and benefit the accumulation of ions in 4I11/2 level

and reduction of ions in 4I13/2 level. Therefore, the 2.7µm emissions can be improved.

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Since GeO2 component was introduced into Er3+ doped tellurite glass, the phonon energy of glass host is enhanced. Thereby, the populations in 4I11/2 level are decreased

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due to larger non-radiative relaxation process (NR). Thus, 2.7 µm emissions and upconversion fluorescence become weaker after the addition of GeO2. Meanwhile, the larger multi-phonon decay rate also makes the 1.55 µm emissions weaker. It is worthy mentioning that the energy transfer (ET) process from Er3+ to OH- ions is harmful for the luminescence especially the mid-infrared emissions. The reduced 2.7 µm

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fluorescence may partially result from increased OH groups which plays an important role in emission quenching during glass fabrication [45,12]. 4 Conclusions

In conclusion, the 2.7 µm spectroscopic properties and energy transfer in Er3+

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doped tellurite glasses are studied. The results show that Er3+ ions doped GeO2 modified tellurite glass possesses better thermal stability (S=11.36°C), larger radiative

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transition probability (95.66 s-1) and emission cross sections (12.75×10-21 cm2) at 2.7 µm. Moreover, the measured 2.7 µm lifetime can reach 124±1 µs with quantum efficiency of 61.5%. In addition, we must find more drying procedures to reduce the OH water level in further work and improve current spectroscopic performance of TZNG glass. Therefore, the prepared Er3+ doped tellurite glass is a promising candidate for mid-infrared laser. Acknowledgment The authors are thankful to Zhejiang Provincial Natural Science Foundation of China (Nos. LY15E020009, LY14B010004, and LR14E020003), National Natural Science 9

ACCEPTED MANUSCRIPT Foundation of China (Nos. 61370049 , 61308090 , 61405182 , 51172252 , 51372235 and 51472225), the International Science & Technology Cooperation Program of China (Grant no. 2013DFE63070), and Public Technical International Cooperation project of Science Technology Department of Zhejiang Province(2015c340009).

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Figure captions Fig.1 DSC curves of prepared tellurite glasses with the heating rate of 10 K/min.

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Fig.2 Absorption spectra in Er3+ doped tellurite glasses. Fig.3 Mid-infrared emission spectra of Er3+ doped tellurite glasses (λex=980 nm); the inset is the decay curve at 2.7 µm excited at 531 nm.

Fig.4 (a) Mid-infrared absorption and emission cross sections; (b) mid-infrared gain

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coefficients in Er3+ doped tellurite glasses.

Fig.5 (a) Upconversion emission spectra; (b) near-infrared emission spectra in Er3+

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doped tellurite glasses.

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Fig.6 Energy level diagram and energy transfer sketch of Er3+ in tellurite glasses.

13

ACCEPTED MANUSCRIPT Table 1 The measured glass transition temperature (Tg), the onset crystallization temperature (Tx) and the calculated thermal stability parameters (∆T and S) in various glasses. The error of ∆T and S has been calculated by the error propagation formulas. Tg (±5°C) Tx (±5°C) Tp (±5°C) ∆T (°C)

Sample

S (°C)

333

468

485

135±6.5

TZNG

335

476

503

141±7.0 11.36±0.57

ZBLAN glass[17]

269

336

358

67±3.4

5.48±0.27

Bismuth glass[18]

370

511

527

141±7.0

6.10±0.30

Germanate glass[8]

618

747

769

129±6.4

4.59±0.23

Tellurite glass[19]

345

468

-

123±6.1

-

SC

M AN U TE D EP AC C

6.89±0.34

RI PT

TZN

ACCEPTED MANUSCRIPT Table 2 J-O intensity parameters Ωt (t=2, 4, 6) of Er3+ in various glasses Ω4 (×10-20

Ω6 (×10-20

δr.m.s

cm2)

cm2)

cm2)

(×10-6)

TZN

8.37±0.06

2.98±0.04

1.99±0.02

0.5

TZNG

9.11±0.05

3.33±0.05

2.27±0.03

0.64

Fluoride glass[29]

2.97

1.59

1.04

-

Bismuth glass[18]

4.71

1.40

0.93

-

6.08

1.76

0.90

-

9.68

1.11

1.89

-

Germanate glass[30]

AC C

EP

TE D

M AN U

Tellurite glass[31]

SC

Sample

RI PT

Ω2 (×10-20

ACCEPTED MANUSCRIPT Table 3 The radiative transition probabilities (Arad, s-1), branching ratios (β, %) and radiative lifetimes (τrad, ms) of Er3+ doped tellurite glasses. TZN

TZNG

Transition Arad

β

τ rad

2.10 529.96

β

Arad

τ rad

I13/2→4I15/2

476.50

100

4

I11/2→4I15/2

524.64

85.76 1.63 592.58

87.13

14.24 -

I9/2 →4I15/2

503.24

75.35 1.50 562.67

→4I13/2

159.90

23.94 -

182.31

24.32 -

→4I11/2

4.76

0.71

4.76

0.63

4

F9/2→4I15/2

5448.54

→4I13/2

285.61

→4I11/2

236.49

→4I9/2 S3/2→4I15/2 →4I13/2 →4I11/2 →4I9/2

4084.53

86.10 1.45 13.90 -

75.05 1.33

-

91.10 0.15

4.77

-

319.82

4.75

-

3.95

-

267.47

3.97

-

0.19

-

12.18

0.18

-

67

0.16 4659.24

67.01 0.14

1667.19

27.35 -

1901.77

27.35 -

130.89

2.15

-

149.11

2.14

-

213.89

3.51

-

242.50

3.49

-

H11/2→4I15/2 24751.25 100

4

F7/2→4I15/2

EP

2

AC C

1.89

91.09 0.17 6133.39

TE D

4

11.17

-

100

SC

4

95.66

M AN U

→4I13/2

RI PT

4

0.04 27090.72 100

0.04

10486.66 99.65 0.10 11898.93 99.69 0.08

ACCEPTED MANUSCRIPT Table 4 The effective emission bandwidth (∆λeff), stimulated emission cross-section (σepeak), the gain bandwidth (∆λeff×σepeak) of 4I11/2→4I13/2 transition in Er3+ doped different glasses. σepeak

(nm)

cm2)

(10-28cm2)

TZN

147.30

10.74

1582.00

TZNG

136.67

12.75

1742.54

ZBLAY glass

96.70

8.98

868.37

151.00

6.50

981.50

PbO-Bi2O3-Ga2O3

AC C

EP

TE D

M AN U

glass

SC

Sample

(10-21 ∆λeff×σepeak References

RI PT

∆λeff

Present work [12]

[42]

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT

Highlights

1. Thermal stability enhanced with the addition of GeO2 into tellurite glass.

RI PT

2. J-O parameters and radiative properties of Er3+ were calculated. 3. The lifetime at 2.7µm was measured to 124±1µs with quantum efficiency of 61.5%.

AC C

EP

TE D

M AN U

SC

4. Emission cross section at 2.7 µm reached 12.75×10-21 cm2.