Codoped Tellurite Glasses Research Articles

White light upconversion emissions from Tm3++Ho3++Yb3+ codoped tellurite and germanate glasses on excitation with 798 nm radiation

White light has been produced using 798 nm laser excitation in Tm3++Ho3++Yb3+ codoped tellurite and germanate glasses. These glasses simultaneously generate the three primary colors, red, green, and blue, on 798 nm excitation. Thus, multicolor emission obtained was tuned to white luminescence by adjusting the Ho3+ ion concentration and excitation power. UV excitation and fluorescence spectra of these triply doped glasses give additional emissions, which do not appear on 798 nm excitation.

Investigation on energy transfer from Er 3+ to Nd 3+ in tellurite glass

A study of energy transfer of Er 3+/Nd 3+ codoped tellurite glasses was presented. By Nd 3+ co-doping, both the Er 3+ green emission corresponding to the Er 3+: ( 4S 3 /2 , 2H 11 /2 ) → 4I 15 /2 transitions and the red emission corresponding to the Er 3+: 4F 9 /2 → 4I 15 /2 transitions were quenched. The energy transfer mechanism between Er 3+ and Nd 3+ was discussed based on their energy level characteristics. The interaction parameters, C D-A, for the energy transfer processes from Er 3+ to Nd 3+ in tellurites glass were calculated. Finally, the resonant transfer Er 3+: 4I 9/2 → Nd 3+: ( 4F 5/2, 2H 9/2) was proposed to be the most probable microscopic process to occur in contrast with the other processes.

Tm 3+-doped tellurite glass with Yb 3+ energy sensitized for broadband amplifier at 1400–1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were perfectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion processes between Tm 3+ and Yb 3+ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm 3+ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and intensity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping process. The potential advantages of Tm 3+/Yb 3+ co-doped tellurite glass as amplifier material were concluded.

Three-color upconversion luminescence of rare earth codoped oxyhalide tellurite glasses

The red, green, and blue upconversion properties of Er 3+/Tm 3+/Yb 3+-codoped oxyhalide tellurite glasses were studied under 980 nm LD excitation. The intense red (657 nm), green (530 and 545 nm), and blue (476 nm) emissions were simultaneously observed at room temperature. The results showed that the mixed halide modified tellurite glass (TZFCB) had strong upconversion emissions. The effect of halide on upconversion intensity was observed and discussed, and possible upconversion mechanisms were evaluated. The intense red, green, and blue upconversion luminescence of Er 3+/Tm 3+/Yb 3+-codoped oxyhalide tellurite glasses might be a potentially useful material for developing three-dimensional displays applications.

Fabrication and gain performance of Er 3+/Yb 3+-codoped tellurite glass fiber

Er 3+/Yb 3+-codoped TeO 2 -ZnO-BaO-La 2O 3 tellurite glass fiber was fabricated by rotation and rod-in-tube technologies. The thermal stability and optical refractive index of the core and cladding glasses were determined by DTA and optical coupler, respectively. The average background loss of tellurite glass fiber was 1.8 dB/m at 1310 nm. Optical microscopy and field emission scanning electron microscope (FESEM) were used to study structural characteristics of preforms and optical fibers. The main loss of tellurite glass fiber could be attributed to scatter centre due to core-cladding interface defects. The amplifier performance of tellurite glass fiber was investigated by pumping with 980 nm laser diode (LD). The gain coefficient and maximum signal gain were 0.21 dB/mW and 10 dB, respectively, for a pumping power of 120 mW. Gains exceeding 5 dB were obtained over 30 nm bandwidth from 1535 to 1565 nm. The minimum noise figure was 4.8 dB at 1557 nm.

Tm 3+/Yb 3+co-doped tellurite glass for broadband optical amplifying over [formula omitted] bands

A kind of novel fluorescence which possesses a potential application in wide-band optical amplifying is reported in this paper. With 975-nm LD laser pumping and Yb 3+-assisted energy transferring, the fluorescence of Tm 3+in the tellurite glass can be measured with emission spectra in 1.4- and 1.6- μ m bands, which would be continued to the 1.53 μ m of the Er 3+. The full-width at half-maximum (FWHM) is 170 nm( 110 + 60 nm), and the lifetimes come up to 0.66 and 1.46 ms. Then, an interpretation was given to the mechanism of IR fluorescence emission which is based on the energy transferring and up-conversion of Tm 3+, Yb 3+ and Er 3+.

Intense white upconversion emission in Pr/Er/Yb codoped tellurite glass

Near infrared sensitized white light emitting glass has been developed and demonstrated. The white light comes from a combination of radiations emitted from triple rare earth ions (Er, Pr, and Yb) doped in tellurite glass. White light emission is possible by suitably mixing the red-green-blue (RGB) intensities emitted from these rare earth ions. The 980 nm radiation sensitized Yb3+ ions transfer their excitation energy to the Er3+ and Pr3+ ions to promote them to the upper states. The green and red emissions come mainly from Er3+ ion whereas blue emission from Yb3+ and Pr3+ ions. The RGB intensities could be adjusted by tuning the rare earth ion concentration. The optical quality of white light was adjudged using the Commission Internationale de l’ Eclairage coordinates by the rare earth ion concentration and incident power density.

Multicolor upconversion emission from Tm3++Ho3++Yb3+ codoped tellurite glass on NIR excitations

Multicolor emission has been produced using 798 nm and 980 nm laser excitation in a Tm3++Ho3++Yb3+ codoped tellurite based glass. This glass generates simultaneously red, green and blue (RGB) emission on 798 nm excitation. Multicolor emission thus obtained was tuned to white luminescence by adjusting the Ho3+ ion concentration. There is a close match between the calculated color coordinate for the white luminescence obtained here and the point of equal energy which represents white in the 1931 CIE chromaticity diagram. The 980 nm excitation of the same sample on the other hand gives intense green and red emission and the glass appears greenish.

Er3+ and Yb3+ concentration effect in the spectroscopic properties and energy transfer in Yb3+/Er3+ codoped tellurite glasses

Spectroscopic properties of Yb3+/Er3+ codoped tellurite glasses as a function of Er3+ and Yb3+ concentration have been investigated. Under 970 nm excitation three strong up-conversion emission bands centred at 525, 546 and 656 nm were observed, and the characteristic near infrared emission band was centred at 1.53 µm. With fluorescence and radiative lifetime the quantum efficiency (QE) of infrared (1.53 µm) and visible upconversion (546 and 660 nm) emissions was calculated. The maximum stimulated emission cross section for 4I13/2 → 4I15/2 transition of Er3+ is 9.7 × 10−21 cm2 for 3/0.5 mol%. The energy transfer (ET) efficiency from Yb3+ to Er3+ (4F5/2) + (4I15/2) → (4 F7/2) + (4I13/2) was calculated, being the maximum ET of 69% for 0.5 mol% of Er3+ with 4.5 mol% of Yb3+. The results indicate that both ET and QE depend mostly on Er3+ rather than on Yb3+ concentration.

Energy transfer and sensitization blue-upconversion in Tm3+ /Yb3+ co-doped tellurite glasses

This paper reports on energy transfer and infrared-to-blue upconversion of Tm3+/Yb3+co-doped tellurite glasses upon excitation with 800 and 980 nm laser diode (LD). The glasses were prepared by the conventional melting method. Their optical spectroscopic properties, direct and indirect sensitization upconversion have been discussed. An intense 475 nm blue upconversion was clearly observed upon excitation of a 980 nm LD. It is interesting to note that the peaks of the blue upconversion at 475 nm changed first to 452 nm, then to 468 nm with increasing Yb-doping concentration upon excitation of a 800 nm LD, which might be due to the indirect sensitization upconversion. To our knowledge, a similar result has not been reported before. The mechanism involved has been explained.

UV–visible emission in Tb–Yb codoped tellurite glass on 980-nm excitation

UV–visible upconversion emission from terbium in a Tb–Yb codoped tellurite glass has been observed on 980-nm excitation. The ultraviolet and violet upconversion emissions involve three photons and the blue, green, yellow, and red emissions arise due to two incident photons. The mechanism involved in these emissions is discussed. The effects of doping concentration and of the sample temperature on the upconversion emissions have also been studied.

Investigation of thermal stability and spectroscopic properties in Er 3+/Yb 3+ co-doped niobic tungsten tellurite glasses

A series of novel Er 3+/Yb 3+ co-doped 75TeO 2–(25 − x)Nb 2O 5– xWO 3 (TNW: x = 0, 3, 6, 9, 12, and 15 mol%) glasses have been prepared. Effect of WO 3 on the thermal stability and spectroscopic properties of Er 3+/Yb 3+ co-doped niobic tellurite glasses have been investigated. With WO 3 content increasing from 0 to 15 mol%, the fluorescence full width at half maximum (FWHM), the peak of stimulated emission cross-section ( σ e peak ), the measured lifetime ( τ m), and quantum efficiency ( η) change from 71 nm, 8.47 × 10 −21 cm 2, 2.86 ms, 84.1% to 76 nm, 7.22 × 10 −21 cm 2, 3.14 ms, 88.9%, respectively. The FWHM and σ e peak of Er 3+ ions in different glass hosts were compared; the obtained data reveals that this new TNW4 glass may be a potentially useful candidate material host for broadband amplifiers.

Thermal-lens study of thermo-optical properties of tellurite glasses

Mode-mismatched Thermal Lens (TL) measurements were performed in 70TeO2–19WO3–7Na2O–4Nb2O5 (% mol) tellurite glasses doped with either Er3+ or Tm3+ and co-doped with Er3+/Tm3+ ions. Thermo-optical parameters (D, K, ds/dQ and ds/dT) were obtained in function of thulium concentrations (0.39–1.6) × 10 20 ions/cm3. For Er3+/Tm3+ co-doped tellurite glasses, D and K values are practically independent of the Tm3+ concentrations used in this study. The average values of D and ds/dT obtained for tellurite glasses are: (3.1 ± 0.2) × 10−3 cm2/s and (16 ± 3) × 10−6 K−1, respectively.

Mid-Infrared Emission Characteristic and Energy Transfer of Ho3+-Doped Tellurite Glass Sensitized by Tm3+

We report on 2.0-microm emission characteristic and energy transfer of Ho3+-doped tellurite glass sensitized by Tm3+ upon excitation of a conventional 808 nm laser diode. The Judd-Ofelt strength parameters, spontaneous radiative transition probabilities and radiative lifetime of Ho3+ have been calculated from the absorption spectra by using the Judd-Ofelt theory. Significant enhancement of 2.0-microm emission of Ho3+ has been observed with increasing Tm3+ doping up to 0.7 mol%. The energy transfer coefficient of the forward Tm3+-->Ho3+ is approximately 17 times larger than that of the backward Tm3+<--Ho3+ energy transfer. Our result indicates that the maximum gain of 2.0-microm emission, assigned to the transition of (5)I7-->(5)I8 of Ho3+, might be achieved from the tellurite glass at the concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. The high gain coefficient and quantum efficiency (1.16) along with the large value of the product of the stimulated emission cross-section and the measured radiative lifetime (4.12 x 10(-27) m(2)s) of the Ho3+/Tm3+-codoped tellurite glasses might find potential applications in efficient 2.0-microm laser.

Investigation of energy transfer and frequency upconversion in Ho 3+/Yb 3+ co-doped tellurite glasses

A serials of Ho 3+/Yb 3+ co-doped tellurite glasses by pumping 970 nm laser diode (LD) were demonstrated to obtain a high efficiency of infrared-to-visible upconversion. Two intense emission bands were observed in Ho 3+/Yb 3+ co-doped tellurite glasses centered at 549 and 664 nm corresponding to Ho 3+: 5S 2( 5F 4)→ 5I 8 and 5F 5→ 5I 8 transitions, respectively. The upconversion intensities of red and green emissions in Ho 3+/Yb 3+ co-doped glasses were enhanced largely when increasing Yb 2O 3 content. The dependence of upconversion intensities on excitation power and the possible upconversion mechanisms had been evaluated by a proper rate equation model. The energy transfer coefficients were estimated by fitting the simulated curves to the measured ones. The obtained three energy transfer coefficients C D 2, C D 3 and C D 4 were C D 2=5.0×10 −18 cm 3/s, C D 3=1.5×10 −17 cm 3/s, C D 4=9.0×10 −17 cm 3/s.

UV/visible upconversion and energy transfer between Nd 3+ and Pr 3+ ions in co-doped tellurite glass

Upconversion emission from Nd 3+ ions in UV/blue region and energy transfer from Nd 3+ ions to Pr 3+ ions has been observed in tellurite glass on excitation with 532 nm radiation. The UV/blue upconversion bands from Nd 3+ ions have been observed at 359, 383, 415 and 451 nm due to the D 3 / 2 4 → I 9 / 2 4 , D 3 / 2 4 → I 11 / 2 4 , D 3 / 2 4 → I 13 / 2 4 and D 3 / 2 4 → I 15 / 2 4 transitions, respectively. The power dependence study shows that all these transitions involve two step photon absorption process. Energy transfer from Nd 3+ ions to Pr 3+ ions results in the observation of upconversion emission bands of Pr 3+ ions at 473, 488, 610 and 647 nm. These emissions from Pr 3+ ions are due to the P 1 3 → H 4 3 , P 0 3 → H 4 3 , P 0 3 → H 6 3 and P 0 3 → F 2 3 transitions, respectively. The involvement of system containing a quartet of ions (Nd–Nd–Pr–Pr) in the energy transfer is supported by the power and concentration dependence studies. The time resolved emission from P 0 3 level of Pr 3+ ions in co-doped samples has been recorded and the occurrence of rise time in the decay curve also supports energy transfer from Nd 3+ to Pr 3+ ions.

Upconversion emissions in Yb3+–Tm3+-doped tellurite glasses excited at 976 nm

Intense Tm3+ blue upconversion emission has been observed in Tm3+-Yb3+ codoped oxyfluoride tellurite glass under excitation with a diode laser at 976 nm. Three emission bands centered at 475, 650 and 796 nm corresponding to the transitions (1)G(4) -> H-3(6), (1)G(4) -> H-3(4) and F-3(4) -> H-3(6), respectively, simultaneously occur. The dependence of upconversion intensities on Tm3+ ions concentration and excitation power are investigated. For fixed Yb2O3 concentrations of 5.0 mol%, the maximum upconversion intensity was obtained with Tm2O3 concentration of about 0.1 mol%. The blue upconversion luminescence lifetimes of the Tm3+ transitions (1)G(4) -> H-3(6) are measured. The results are evaluated by the possible upconversion mechanisms.

Energy transfer in Pr3+/Yb3+ codoped tellurite glasses

Resonant energy transfer between Pr3+ and Yb3+ ions has been studied in tellurite glasses. The energy absorbed by Pr3+ is transferred efficiently to Yb3+, and fluorescence at around 1μm wavelength is observed. The energy transfer efficiencies for the 3P0→3F2 and 1D2→1G4 transitions in 0.5wt% Pr3+–1.0wt% Yb3+ codoped tellurite glasses are ∼68% and ∼84%, respectively, and the emission intensity of the 1G4→3H5 transition of Pr3+ does not show any significant change, due to a possible back transfer energy from the 2F5/2→2F7/2 transition of Yb3+ to the 1G4 level of Pr3+.

2.0 μm emission properties and energy transfer of Tm3+/Ho3+-codoped tellurite glass

This paper reports on spectroscopic properties and energy transfer of Tm3+/Ho3+-codoped ZnO-WO3-TeO2 glass upon excitation of 808nm diode laser. The J-O strength parameters， spontaneous emission probability and radiative lifetime of Ho3+ were calculated using Judd-Ofelt theory. The absorption cross-section and stimulated emission cross-section were also investigated. Our result indicates that the highest gain of 2.0 μm emission, which comes from 5I7 to 5I8 transition of Ho3+, might be achieved from the glass at the rare-earth ion concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. It is found that coefficients of the forward Tm3+→Ho3+ energy transfer is about 18 times that for the backward Tm3+←Ho3+ energy transfer. The calculated fluorescence lifetime of the 5I7 level of Ho3+ is 3.9 ms and the emission cross section of the 5I7→5I8 transition of Ho3+ exhibits a maximum of 9.15×10-21 cm2 at 2027 nm. We also found that Tm3+/Ho3+-codoped tellurite glass is a promising host material for potential 2.0 μm laser by comparing the quantum efficiencies, the values of σe×τm and gain coefficients of fluoride and heavy metal oxide glasses respectively.

Upconversion luminescence in Yb3+ sensitized Er3+/Yb3+-codoped tellurite glasses

A series of Er3+/Yb3+-codoped，Ho3+/Yb3+-codoped，and Er3+/Yb3+/Ho3+-triply doped tellurite glasses were prepared by high-temperature melting. Under 975nm laser light excitation，intense green and red upconversion luminescence was observed in all the three kinds of codoped tellurite glasses. The influence of Yb3+ ions on the upconversion emission properties of Er3+ and Ho3+ ions was investigated as well as the energy transfer efficiencies of Yb3+→Er3+ and Yb3+→Ho3+. Upconversion luminescence mechanisms of Er3+ and Ho3+ sensitized by Yb3+ in tellurite glasses were discussed. When the concentrations of Er3+ and Ho3+ ions were fixed at low values，the intensity of green and red upcoversion emission in Er3+/Yb3+/Ho3+-triply doped tellurite glasses increases with increasing Yb2O3 content, which are due to the interaction overlap of Er3+：4S3/2→4I15/2 and Ho3+：5S2(5F4)→5I8 transitions，Er3+：4F9/2→4I15/2 and Ho3+：5F5→5I8 transitions，respectively. In Er3+/Yb3+/Ho3+-triply doped tellurite glasses，the upconversion luminescence mechanisms were affected by the interaction energy transfers of Er3+/Yb3+, Ho3+/Yb3+ and Er3+/Ho3+. The cross-relaxation between Er3+ and Ho3+ enhances the upconversion emission intensities of Ho3+ in the visible region.