Spectroscopic properties in Er³⁺/Yb³⁺ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er 3+ /Yb 3+ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er 3+ and Yb 3+ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd–Ofelt theory, the oscillator strength was computed. The lifetime of 4 I 13/2 level (τ m ) of Er 3+ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er 3+ was calculated by the McCumber theory. The spectroscopic properties of Er 3+ ion were compared with those in different glasses. The full width at half maximum and σ e are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.     

Spectroscopic properties in Er Er3+/Yb3+Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er³⁺/Yb³⁺ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er³⁺ and Yb³⁺ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd-Ofelt theory, the oscillator strength was computed. The lifetime of ⁴I_13/2 level (τ_m) of Er³⁺ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 τ_m. The large stimulated emission cross section of the Er³⁺ was calculated by the McCumber theory. The spectroscopic properties of Er³⁺ ion were compared with those in different glasses. The full width at half maximum and σ_e are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.     

Composition Dependence of Spectroscopic Properties of Er^3＋ Doped TeO2-WO3-ZnO Glasses

Er^3 -doped TeO2-WO3-ZnO glasses were prepared and the absorption spectra, emission spectra and fluorescence lifetimes were measured. With more Te02 content in the glasses, the emission full width at half maximum (FWHM) increases while the lifetime of the ^4I13/2 level of Er^3 decreases. The stimulated emission cross-sectionof Er^3 calculated by the McCumber theory is as large as 0.86pm^2. The product of the FWHM and the emissioncross-section σe of Er^3 in TeO2-WO3-ZnO glass is larger than those in other glasses, which indicates that the glasses are promising candidates for Er^3 -doped broadband amplifiers. The Judd-Otfelt parameter Ω6 shows close composition dependence of the 1.5μm emission bandwidth. The more the TeO2 content is, the larger thevalues of Ω6 and FWHM.     

Spectral Properties of Erbium—Doped Oxyfluoride Silicate Glasses for Broadband Optical Amplifiers

The new oxyfluoride silicate glasses of Er^3 -doped 50SiO2-(50-x) PbO-xPbF2 were prepared. With increasing PbF2 content in the glass composition, the fluorescence full width at half maximum and lifetimes of the ^4I13/2 level of Er^3 increase, while the refractive indices and densities decrease. Er^3 -doped 50SiO2-50PbF2 glass showed broad fluorescence spectra of 1.55μm with a large stimulated emission cross-section and long lifetimes of ^4I13/2 level of Er^3 . Compared with other glass hosts, the gain bandwidth properties of Er^3 -doped 50SiO2-50PbF2 glass are close to those of tellurite and bismuth glasses, and have advantages over those of silicate, phosphate and germante glasses. The broad and flat ^4I13/2→^4I15/2 emission of Er^3 around 1.55μm can be used as host material for potential broadband optical amplifier in wavelength-division-multiplexing network system.     

Er~(3+)/Yb~(3+) codoped phosphate glass laser end-pumped by laser diode

An Er3 /Yb3 phosphate laser glass was fabricated and characterized. According to McCumber theory, the stimulated emission cross-section of Er3 ions at 1533 nm calculated by absorption spectrum was 0.84×10-20 cm2, and the fluorescence lifetime of 4I13/2 level was 8.5 ms. Continuous wave (CW) laser operation of this Er3 /Yb3 phosphate glass pumped by laser diode (LD) was demonstrated at room temperature. The maximum output power of 80 mW and slope efficiency of 16.5% were obtained.     

Determination of energy constants for Yb3＋/Er3＋ transfer and upconversion codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.     

Broadband Infrared Luminescence of Ni^2＋ in Petalite-Type Transparent Glass Ceramics

Transparent Ni^2＋-doped magnesium aluminosilicate glass ceramics are prepared. The formation of petalite-type crystallites in the glass ceramics is confirmed by x-ray diffraction. Broadband infrared luminescence centred at around 1235nm with full width at half maximum （FWHM） of about 300nm is observed from the Ni^2＋-doped glass ceramics. The observed infrared emission could be attributed to the ^3T2（F） → ^3A2（F） transition of octahedral Ni^2＋ ions in petalite-type crystallites. Theproduct of the fluorescence lifetime and the stimulated emission cross sections is 1.2 ×10-24 cm^2s.     

Mixed Former Effect：A Kind of COmposition Adjusting Method of Er—Doped Glass for Broadband Amplification

A compositional adjusting method called the mixed former effect is proposed to improve effectively optical properties such as the emission cross sectionk,the fluorescence full width at half maximum(FWHM)and the lifetime of the 4I13/2 level of Er-doped glass.A kind of Er-0doped bismuth-based glass illustrated high emission cross section (σe^p=0.66-0.90pm^2),large fluorescence FWHM(68-85nm),and relatively long lifetime of the ^4I13/2 level(Tm=1.6-4.3ms) using this method.A comparison of spectroscopic parameters shows that bismuth based glass is much better for broadband amplifiers than other glass hosts.     

Effect of lithium-potassium mixed alkali on spectroscopic properties of Er^3＋-doped aluminophosphate glasses

Er^3＋-doped lithium-potassium mixed alkali aluminophosphate glasses belonging to the oxide system xK2O-（15-x）Li2O-4B2O3-11Al2O3-5BaO-65P2O5 are obtained in a semi-continuous melting quenching process. Spectroscopic properties of Er^3＋-doped glass matrix have been analysed by fitting the experimental data with the standard Judd-Ofelt theory. It is observed that Judd-Ofelt intensity parameters Ωt（t = 2, 4 and 6） of Er^3＋ change when the second alkali is introduced into glass matrix. The variation of line strength Sed[^4I13/2,^4I15/2] follows the same trend as that of the/26 parameter. The effect of mixed alkali on the spectroscopic properties of the aluminophosphate glasses, such as absorption cross-section, stimulated emission cross-section, spontaneous emission probability, branching ratio and the radiative lifetime, has also been investigated in this paper.     

Er3+/Yb3+ codoped phosphate glass laser end-pumped by laser diode

An Er3+/yb3+ phosphate laser glass was fabricated and characterized. According to McCumber theory, the stimulated emission cross-section of Er3+ ions at 1533 nm calculated by absorption spectrum was 0.84 × 10-20 cm2, and the fluorescence lifetime of 4I13/2 level was 8.5 ms. Continuous wave (CW) laser operation of this Er3+/Yb3+ phosphate glass pumped by laser diode (LD) was demonstrated at room temperature. The maximum output power of 80 mW and slope efficiency of 16.5% were obtained.     

Energy transfer mechanism in Er3＋ doped fluoride glass sensitized by Tm3＋ or no3＋ for 2.7-μm emission

Enhanced 2.7 μm emission is obtained in Er3＋/Tma＋ and Era＋/Ho3＋ codoped ZBYA glasses. Absorp- tion and emission spectra are tested to characterize the 2.7 μm emission properties of Era＋/Tm3＋ and Era＋/Ho3＋ doped ZBYA glasses and a reasonable energy transfer mechanism of 2.7 μm emission between Er3＋ and Tm3＋Ho3＋） ion is proposed. Codoping of Tm3＋ or Ho3＋ significantly reduces the lifetime of the Era＋： 4I13/2 level due to the energy transfer of Er3＋：4I13/2 →Tm3＋：3F4 or Er3＋：4I13/2 →Ho3＋： 5I7. Thus, the 2.7μm emission is strengthened and the 1,5μm emission is decreased accordingly especially in the Era＋/Tma＋ sample. The upconversion effects between the Er3＋/Tm3＋ and Er3＋/Ho3＋ doped ZBYA glasses are different attribute to the different energy transfer efficiencies. Both of the two codoped samples possess nearly equal large emission cross section （16.6 × 10 -21 cm-2） around 2.7 μm. The results indicate that this Er3＋/Tm3＋ or Er3＋/Ho3＋ doped ZBYA glass has potential applications in 2.7 μm laser.     

Broadband Near-Infrared Emission from Transparent Ni^2＋ -Doped Sodium Aluminosilicate Glass Ceramics

Broadband near-infrared emission from transparent Ni^2＋-doped sodium aluminosilicate glass-ceramics is observed. The broad emission is centred at 1290nm and covers the whole telecommunication wavelength region （1100- 1700hm） with full width at half maximum of about 340hm. The observed infrared emission could be attributed to the 3T2（F） → 3A2（F） transition of octahedral Ni^2＋ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15 × 10^-24 cm^2s. It is suggested that Ni^2＋- doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.     

New chemically stable Er_(3+)-Yb_(3+) co-doped phosphate glass for optical waveguide lasers and amplifiers

A set of phosphate glasses with different amounts of Al2O3, Na2O, La2O3 and AlF3 contents were prepared to search for a phosphate glass which is suitable for ion-exchange process. Based on chemical durability test results and spectroscopic properties, a glass with excellent chemical durability and good spectroscopic properties is developed for ion-exchange process. The emission cross section of Er3+ in this glass is calculated to be 0.72×10~20 cm2 by McCumber theory. The planar waveguide with three modes at 632.8 nm and one mode at 1540 nm can be realized by 335℃ 3 hours ion-exchange in 5%AgNO3+95%KNO3 molten salt.     

Transparent Ni^2＋-Doped MgO-Al2O3-SiO2 Glass Ceramics with Broadband Infrared Luminescence

We report on transparent Ni^2＋-doped MgO-Al2O3-SiO2 glass ceramics with broadband infrared luminescence. Ni^2＋-doped MgO-Al2O3-SiO2 glass is prepared by using the conventional method. After heat treatment at high temperature, MgAl2O4 crystallites are precipitated, and their average size is about 4.3 nm. No luminescence is detected in the as-prepared glass sample, while broadband infrared luminescence centred at around 1315 nm with full width at half maximum （FWHM） of about 300 nm is observed from the glass ceramics. The observed infrared emission could be attributed to the ^3T2g（^3F）→^3A2g（^3F） transition of octahedral Ni^2＋ ions in the MgAl2O4 crystallites of the transparent glass ceramics. The product of the fluorescence lifetime and the stimulated emission cross section is about 1.6×10^-24 s cm^2.     

Er^3＋ and Yb^3＋ Codoped Phosphate Laser Glass for High Power Flashlamp Pumping

A novel yb^3＋-Er^3＋ codoped phosphate glass for high power flashlamp pumping and high repetition rate laser at 1.54μm, designated EAT5-2, is developed. The weight-loss rate of is 1.3 × 10^-5 gcm^-2h^-1 in boiling water, which is comparable to Kigre＇s QX-Er glass. Some spectroscopic parameters are analysed by Judd-Ofelt theory and McCumber theory. The emission cross section is calculated to be 0.73 × 10^-20 cm^2. The thermo-mechanical properties of EAT5-2 are modified after an ion-exchange chemical strengthening process in a KNO3/NaNO3 molten salt bath. The thresholds for optical damage from the flashlamp pumping are tested on glass rods. A repetition rate of 15 Hz is achieved for chemically strengthened glass. The laser experimental results at 1.54 μm from flashlamp pumping are also reported.     

Effects of Yb^3＋ in Er^3＋/Yb^3＋ Codoped Fluorophosphate Glasses

For the Er^3＋ /Yb^3＋ codoped fluorophosphate glasses, Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but an average component on the spectroscopic properties around 1530nm emission. The double roles of Yb^3＋, as a sensitizer and as an average component, are discussed. It is found that Yb^3＋ as an average component contributes to the increase of fluorescence lifetime, and Yb^3＋ as a sensitizer has the best sensitization when its concentration is 2.4 mol%.     

Optical transitions and upconversion properties of Er^3＋-doped chloride tellurite glasses

Er^{3+}-doped lead chloride tellurite glasses were prepared using the conventional melting and quenching method. The absorption spectra were measured and the Judd－Ofelt analysis was performed. The spectroscopic parameters such as the intensity parameters, transition probabilities, radiative lifetimes, and branching ratios were obtained. Intense infrared emission and visible upconversion luminescence under 976 nm excitation were observed. For the 1.55μm emission, the full width at half maximum and the emission cross sections are more than 50 nm and 8×10^{- 20}cm^2, respectively. Three efficient visible luminescences centred at 525, 547, and 658nm are assigned to the transitions from the excited states {}^{2}H_{11/2}, {}^{4}S_{3/2}, and {}^{4}F_{9/2} to the ground state {}^{4}I_{15/2}, respectively. The upconversion mechanisms and the power-dependent intensities are also discussed and evaluated.     

Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） Glasses for 1.47-μm Optical Amplifications

We report the spectroscopic properties and thermal stability of Tm^3＋-doped Ga2O3-GeO2-Bi2O3-PbO（PbF2） glasses for 1.47-μm optical amplifications. Effects of PbF2 doping on the optical properties and thermal stability of Tm^3＋ -doped gallate-germanium-bismuth-lead glass are inestigated. The measured peak wavelength and full width at half-maximum of the fluorescence are 1465nm and - 120 nm, respectively： Siguificant enhancement of the 1.47-μm emission and the lifetime of a a^3H4 level with increasing PbF2 doping have been observed. The presence of GeO2 provides two potentials of increasing the thermal stability and shortening the ultraviolet cutoff band of host glasses.     

Visible Upconversion Emission in Er3＋—Doped GeO2—PbO—PbF2 Glass

The upconversion fluorescence emission of Er3 -doped 60GeO2-2OPbO-2OPbF2 glass was experimentally investigated under the pump of 976-nm laser diode. The results reveal the existence of intense emission bands centred around 524, 545, and 657nm at room temperature. The green emission at 524 and 545nm is due to the 4S3/2 2 Hll/2→ 4I15/2 transition and the red emission of 657nm originates from the 4F9/2-→4I15/2 transition of Er3 . The quadratic dependence of the green and red emissions on excitation power indicates that a two-photonabsorption process occurs under the 976-nm excitation. The excited- state absorption from 4I ll/2 and the cross relaxation between two Er3 ions in the 4I ll/2 state contribute to the green emission. The red emission at 657nm is attributed to the excited-state absorption and cross relaxation processes in the 4I13/2 level as well as the 4S3/2 level nonradiative transition of Er3 .     

Broadband 1.5-um emission of erbium-doped TeO_2-WO_3-Nb_2O_5 glass for potential WDM amplifier

Erbium-doped glass showing the wider 1.5-um emission band is reported in a novel oxide system TeO2-WO3-Nb2O5 and their thermal stability and optical properties such as absorption, emission spectra, cross-sections and fluorescence lifetime were investigated. Compared with other glass hosts, the gain bandwidth properties of Er3+ in TWN glass is close to that of bismuth glasses, and larger than those of tellurite, germanate, silicate and phosphate glasses. The broad and flat 4I13/2-4I15/2 emission and the large stimulated emission cross-section of Er3+ ions around 1.5um can be used as host material for potential broadband optical amplifier in the wavelength-division-multiplexing (WDM) network system.