Codoped Tellurite Fiber Research Articles

A temperature sensor based on Er3+/Yb3+ co-doped tellurite fiber for real-time thermal monitoring of transformers

In this paper, a temperature sensor based on fluorescence intensity ratio (FIR) technique is prepared by the dual curing method. The pumping threshold is only 0.1 mW for the application of real-time thermal monitoring on small transformers. This not only greatly reduces the thermal effects accumulated by laser irradiation but also contributes to the integration and portability of the light source. Based on the FIR, the temperature information could be demodulated through tracking the fluorescence spectral changes. The basic temperature sensing characteristics of this sensor were evaluated, which showed that the maximum stability deviation and reproducibility error were within ±1.1 K and ±0.8 K, respectively. Notably, it has a maximum measurement error of only 0.61 K when applied to the temperature monitoring of transformers. And a fast time response of 2.1 s was exhibited in the cyclic exhalation experiment. This proposed sensor is suitable for mass production due to its resistance to electromagnetic interference, low pumping power, fast time response, excellent stability and reproducibility.

20 μm Nd^3+/Ho^3+-doped tungsten tellurite fiber laser

Tellurite glass has emerged as a promising ~2.0 μm laser material owing to its excellent features of supporting efficient mid-infrared emission and easy fiber-pulling over the commonly investigated glasses. In this paper, we report an efficient ~2.0 μm laser output from a new-type of Nd3+/Ho3+ co-doped tungsten tellurite fiber laser by using an ultra-short length fiber of 5 cm upon a 795 nm laser diode. The tellurite fibers have been fabricated by a suction technique with the core and cladding diameters of 32 and 125 μm, respectively. The propagation loss of the fiber is measured to be 4.44 dB/m at 1310 nm by using the cutback method. The large energy transfer coefficient from Nd3+ to Ho3+ (3.8 × 10−40 cm6·s–1) and high gain coefficient of Ho3+: 5I7 → 5I8 transition (1.2 cm–1) have confirmed the success of using Nd3+ as sensitizer to realize the ~2.0 μm laser emission of Ho3+. The maximum output power of the laser is obtained to be 12 mW at a center wavelength of 2052 nm with a slope efficiency of 11.2%. The laser threshold is as low as 38 mW, which is around one order of magnitude lower than the previously reported Tm3+/Yb3+ doped tellurite fiber lasers with the similar pump scheme and fiber geometry. The results indicate that the Nd3+/Ho3+ co-doped tungsten tellurite glass fiber laser is a promising laser medium candidate for achieving the ultra-compact and efficient ~2.0 μm laser.

Optical and spectroscopic characterization of Er3+–Yb3+co-doped tellurite glasses and fibers

Optical and spectroscopic properties of Er3+–Yb3+ co-doped TeO2–WO3–Nb2O5–Na2O–Al2O3 glasses and fibers were investigated. Emission spectra and fluorescence lifetimes of 4I13/2 level of Er3+ion as a function of rare earth concentration and fiber length were measured in glasses. Results show that the self-absorption effect broadens the spectral bandwidth of 4I13/2→4I15/2 transition and lengthens the lifetime significantly from 3.5 to 4.6ms. Fibers were fabricated by the rod-in-tube technique using a Heathway drawing tower. The emission power of these Er3+–Yb3+ co-doped Step Index Tellurite Fibers (SITFs; lengths varying from 2 to 60cm) were generated by a 980nm diode laser pump and then the emission power spectra were acquired with an OSA. The maximum emission power spectra, within the 1530–1560nm region, were observed for fiber lengths ranging from 3 to 6cm. The highest bandwidth obtained was 108nm for 8cm fiber length around 1.53µm.

Improvement of 1.53 μm emission and energy transfer of Yb3+/Er3+ co-doped tellurite glass and fiber

To improve the 1.53μm band emission of Er3+, the trivalent Yb3+ ions were introduced into the Er3+ single-doped tellurite glass with composition of TeO2–ZnO–La2O3, a potential gain medium for Er3+-doped fiber amplifier (EDFA). The improved effects were investigated from the measured 1.53μm band and visible band spontaneous emission spectra together with the calculated 1.53μm band stimulated emission (signal gain) spectra under the excitation of 975nm laser diode (LD). It was found that Yb3+/Er3+ co-doping scheme can remarkably improve the visible band up-conversion and the 1.53μm band fluorescence emission intensity, and meanwhile improves the 1.53μm band signal gain to some extent, which were attributed to the result of the effective energy transfer of Yb3+:2F5/2+Er3+:4I15/2→Yb3+:2F7/2+Er3+:4I11/2. The quantitative study of energy transfer mechanism was performed and microscopic energy transfer parameters between the doped rare-earth ions were determined. In addition, the spectroscopic properties of Er3+ were also investigated from the measured absorption spectrum according to the Judd–Ofelt theory, and the structure behavior and thermal stability of the prepared tellurite glass were analyzed based on the X-ray diffraction (XRD) and differential scanning calorimeter (DSC) measurements, respectively.

Green upconversion emission in tellurite optical fibre codoped with Yb3+/Er3+

In the paper the spectroscopic properties of Yb 3+ /Er 3+ codoped tellurite glass has been investigated. Upconversion luminescence at 525 nm, 546 nm, 651 nm corresponding to the Er 3+ : 2 H 11/2 -> 4 I 15/2 , 4 S 3/2 -> 4 I 15/2 , 4 F 9/2 -> 4 I 15/2 transitions, respectively was obtained as a result of energy transfer between Yb 3+ and Er 3+ ions. Developed tellurite glass characterized by highest intensity of upconversion luminescence (0.5mol% Yb( 2 O 3 /0.1mol% Er 2 O 3 ) was used as core of optical fiber. The amplified spontaneous emission in the fabricated optical fiber resulting from the optical transition in the structure of erbium was observed. Full Text: PDF References J. Zhang, S. Dai, G. Wang, L. Zhang, H. Sun, L. Hu., "Investigation on upconversion luminescence in Er3+/Yb3+ codoped tellurite glasses and fibers", Physics Letters A 345, 409?414 (2005). CrossRef D. Lande, S.S. Orlov, A. Akella, L. Hesselink, R. R. Neurgaonkar, "Digital holographic storage system incorporating optical fixing", Optics Letters, Vol. 22, Issue 22, 1722-1724 (1997). CrossRef T. Yamashita, Y. Ohishi, "Spectroscopic properties of Tb3+-Yb3+-codoped borosilicate glasses for green lasers and amplifiers", Proc. SPIE 6389, 638912 (2006). CrossRef Y.H. Li, G.Y. Hong, Y.M. Zhang, Y.M. Yu, "Red and green upconversion luminescence of Gd2O3:Er3+, Yb3+ nanoparticles", J. Alloys Compd. 456, 247-450 (2008). CrossRef J. S. Wang, E. M. Vogel, E. Snitzer, "Tellurite glass: a new candidate for fiber devices", Opt. Mater. 3, 187-203 (1994). CrossRef J. Dorosz, "Optical Fibers Technology", Ceramics vol. 86 (2005)

Fabrication and upconversion luminescence of Er3+/Yb3+ codoped TeO2–WO3–Na2O–Nb2O5–Al2O3 glass fibers

The tellurite fibers based on glasses with the composition TeO2–WO3–Nb2O5–Na2O–Al2O3–Er2O3–Yb2O3 were fabricated by the rod-in-tube technique using a Heathway drawing tower. The upconversion luminescence of Er3+/Yb3+ codoped tellurite glass fibers under 980nm excitation were investigated. The Er3+/Yb3+co-doped tellurite fibers show an efficient up-conversion process in comparison with the Er3+-doped tellurite fibers. The pump power dependent intensities were discussed, which showed that two photons are involved in the upconversion process.

Dual-Pumped Tellurite Fiber Amplifier and Tunable Laser Using Er$^{3+}$/Ce$^{3+}$ Codoping Scheme

We have demonstrated a high-performance Er3+/Ce3+ codoped tellurite fiber amplifier and tunable fiber laser using a dual-pumping scheme. The short 22-cm Er3+/Ce3+ ion codoped fiber exhibits a net gain of 28 dB at 1558 nm, a wide positive net gain bandwidth of 122 nm, and a noise figure of 4.1 dB. Finally, a widely tunable Er3+ /Ce3+ codoped tellurite fiber ring laser with a tuning range of 83 nm is demonstrated.

Numerical Rate Equation Modeling of a ${\sim {\hbox {2.1}}-}\mu{\hbox {m}}-{\rm Tm}^{3+}/{\rm Ho}^{3+}$ Co-Doped Tellurite Fiber Laser

Judd-Ofelt analysis is performed on measurements of bulk samples of Tm3+- and Ho3+-doped tellurite glass from which the host-dependent Judd-Ofelt intensity parameters are extracted. These have then been used to calculate the radiative rates and branching ratios in this particular material system. A rate-equation approach is then used to model an experimentally realized ~2.1 μm Tm3+/Ho3+ codoped tellurite fiber laser and extract values of the energy transfer and upconversion rate parameters in TeO2-ZnO-Na2O (TZN) glass. Excellent agreement is found between simulated and experimental data, which indicates the validity of the approach.

${\hbox {Er}}^{3+}-{\hbox {Tm}}^{3+}$-Codoped Tellurite Fiber Amplifiers for WDM Systems: A Theoretical Analysis of BER and Bandwidth

WDM systems cascaded by Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> -Tm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> -codoped tellurite fiber amplifiers pumped by 800- and 980-nm lasers are analyzed for the first time in this paper. We use an amplifier model based on propagation and population-rate equations that are solved numerically using the Runge-Kutta algorithm and Newton's iterative method. In addition to analyzing the performance of the 800-nm pump, we also study the performance improvement after adding a new pump of 980 nm. With this new 980-nm pump, channels in the 1420-1620-nm wavelength region can reach a bit error rate (BER) less than 1times10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> , with a transmission distance of 400 km.

Tm^3+/Ho^3+ codoped tellurite fiber laser

Continuous-wave and Q-switched lasing from a Tm(3+)/Ho(3+) codoped tellurite fiber is reported. An Yb(3+)/Er(3+)-doped silica fiber laser operating at 1.6 microm was used as an in-band pump source, exciting the Tm(3+) ions into the (3)F(4) level. Energy is then nonradiatively transferred to the upper laser level, the (5)I(7) state of Ho(3+). The laser transition is from the (5)I(7) level to the (5)I(8) level, and the resulting emission is at 2.1 microm. For continuous wave operation, the slope efficiency was 62% and the threshold 0.1 W; the maximum output demonstrated was 0.16 W. Mechanical Q switching resulted in a pulse of 0.65 microJ energy and 160 ns duration at a repetition rate of 19.4 kHz.

Theoretical analysis of gain characteristics of Er/sup 3+/-Tm/sup 3+/-codoped tellurite fiber amplifier

The rate and power propagation equations of Er3+ and Tm 3+-codoped tellurite fiber amplifier pumped by 800-nm laser are presented and solved to analyze the dependences of gain at both 1470 and 1530 nm on the codoping concentration of Er3+ and Tm3+, fiber length, and input signal power. The numerical results show that with pump power of 200 mW and fiber length of 1.5 m, the gain at both 1470 and 1530 nm may reach 12.0 dB when the codoping concentration of Er3+ and Tm3+ reach 4.0times10 25 ions/m3, 3.2times1025 ions/m3 , respectively. The fiber length and codopant concentrations are proposed to make the two channels equivalently amplified

Gain improvement by internal laser cavity in Tm3+/Yb3+-co-doped tellurite fiber amplifier pumped by 980-nm laser

S-band Tm(3+)/Yb(3+) co-doped tellurite fiber amplifier pumped by a 980 nm laser diode is proposed and modeled taking into consideration of the energy transfer process from Yb(3+) to Tm(3+) and the laser cavity inside a co-doped fiber amplifier. S-band spectral gains for the co-doped fiber amplifiers are investigated. The results show that considerable gain improvement can be achieved by constructing 1050nm laser cavity inside the amplifier.

Er 3+–Tm 3+ co-doped tellurite fibers for broadband optical fiber amplifier around 1550 nm band

Tellurite fibers with 7500 ppm Er 3+ concentration and diverse 2500–15,000 ppm Tm 3+ concentrations were manufactured, and their amplified spontaneous emission (ASE) intensities 1550 nm band around were obtained for 980 and 790 nm pump laser. Maxima 187 nm bandwidth at −3 dB points using Er 3+–Tm 3+ co-doped tellurite optical fibers pumping at 790 nm was obtained, and energy transfer (ET) process between 4I 13/2 Er 3+ and 3F 4 Tm 3+ levels related with the amplifier quantum efficiency was studied from experimental and calculated lifetime.

Investigation on upconversion luminescence in [formula omitted] codoped tellurite glasses and fibers

The upconversion properties of Er 3 + / Yb 3 + codoped tellurite glasses and glass fibers with D-shape cladding under 980 nm excitation were investigated. Intense emission bands centered at 531, 546 and 658 nm corresponding to the transitions Er 3 + : H 11 / 2 2 → I 15 / 2 4 , S 3 / 2 4 → I 15 / 2 4 and F 9 / 2 4 → I 15 / 2 4 , respectively, were observed at room temperature. Compared with that in Er 3 + / Yb 3 + codoped tellurite bulk glass, the upconversion luminescence becomes more efficient in the fiber geometry. The dependence of upconversion intensities on fiber geometry and possible upconversion mechanism are discussed and evaluated. The presented Er 3 + / Yb 3 + codoped tellurite fibers with intense upconversion luminescence can be used as potential host materials for upconversion fiber lasers.

Fabrication and emission properties of Er 3+/Yb 3+ codoped tellurite glass fiber for broadband optical amplification

Tellurite glass is proposed as a host for broadband erbium-doped fiber amplifiers because of their excellent optical and chemical properties. A new single mode Er 3+/Yb 3+ codoped tellurite fiber with D-shape cladding geometry is fabricated in this work. When pumped at 980 nm, a broad erbium amplified spontaneous emission (ASE) nearly 100 nm in the wavelength range of 1450–1650 nm around 1.53 μm is observed. It was found that the emission spectrum from erbium in tellurite glass fibers is almost twice as broad as the corresponding spectrum in tellurite bulk glass. The changes in ASE with regard to fiber lengths and pumping power were measured and discussed. The output of about 2.3 mW from Er 3+/Yb 3+ codoped tellurite fiber ASE source is obtained under the pump power of 700 mW. The broad 1.53 μm emission of Er 3+ in Er 3+ /Yb 3+ codoped tellurite glass fiber can be used as host material for potential broadband optical amplifier and tunable fiber lasers.

Visible emissions at 592 and 613 nm in Er3+–Eu3+-codoped tellurite fibers

The Er3+–Eu3+-codoped tellurite fibre was pumped at 800 nm (CW) using a Ti–sapphire tunable laser source. The emission spectra at 592 and 613 nm, both attributed to Eu3+ transitions from 5D0→7F1 and 5D0→7F2, respectively, were recorded at room temperature. Although the upconversion fluorescence from the Er3+:4S3/2 level is well known, the observed efficient energy transfer from the Er3+:(2H11/2, 4S3/2) levels to the Eu3+:(5D1, 5D0) levels is not known in the literature. The calculated energy transfer efficiency is approximately 20%. The observed visible emissions point out that the Er3+–Eu3+-codoped tellurite fibre is a potential host material for designing a 589 nm laser for satellite communication and a compact 613 nm fibre laser for medical applications.